Battery performance change after watering?

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Battery performance change after watering?

Rob Trahms
Hi all -
I still consider myself a newbie with regards to battery chemistry.  With my conversion,  I would semi-regularly eyeball electrolyte levels in my US125s after charging to make sure they were correct and not in need of topping off.  In most cases, the levels looked right and none of the plates were exposed, so I didn't mess.  Recently I purchased one of those battery fillers with the auto shutoff to help be more exact, and when I used it for the first time, ALL the cells required water.  I used up about a gallon and a half of water across 16 of these batteries!  Anyway...

My question is about performance of the batteries after refilling.  Since the water levels were apparently low, but not super low, would I notice any substantial difference in how the batteries perform after topping off?  Maximum SG difference, or anything like that?  My thought is probably not, but I wanted to check with those who have more experience here.

Thanks,
Rob
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Re: Battery performance change after watering?

Roland Wiench
Hello Rob,

Adding water to a battery initially, the water being lighter than the acid
is floating on top of the heaver acid.  Even if a battery has been setting
for a long time, this same effect happens where the specific gravity at the
top may be less than the electrolyte at the bottom.

At this time when you use a initially fill battery or use a battery that's
been idle for a long time, the top portion of the grids has less conductance
then at the bottom. Therefore you have less conductance at the top of the
plates then you have at the bottom at this time.

It is normal in some high ampere-hour batteries, that when the electrolyte
level is at the correct level and the water is correctly mix by a finish
charge, that as it is being discharge, the electrolyte level may drop.  Then
when charging the batteries, this electrolyte will rise.

Just make sure that when you are at the most discharge point that you may
want to go, the electrolyte level is just about the plates.  If not, then
add just enough water to get about 1/8 inch above the plates.  Then you
charge the battery to about 80 to 90 percent and then finish adding the
water.  Finish charge the battery to 100 percent which at this time will
give you a better mix of water that is floating on top and the acid at a
lower level.

The performance is going to depend on the right time and methods you add the
water and getting a proper mix.  You then take a specific gravity reading
just after the completion of the finish charge.

One gallon per 15 batteries of your size is about right.  I normally use one
gallon per 12 batteries every 6 months discharging the batteries to 80
percent of charge or 20 Depth of Discharge.  I normally charge the batteries
for 15 minutes at 25 amps each day just before I leave.  This initial high
battery voltage seems to get me another mile at a lower battery voltage than
if I charge the batteries a day before.

The formula for electrolyte mixing is:

Five parts of water  =  5 x H2O    or  5 x 1.0 SG = 5.0
Three parts of acid  =  3 x H2SO4  or  3 x 1.8 SG = 5.4

Therefore the average becomes for eight parts = (5.0 + 5.4)/8 = 1.3 SG

When mixing, the 1.3 SG is hot, so when it cools, the final specific gravity
reading will come to 1.277 SG. for 100 percent state of charge.

Roland




----- Original Message -----
From: "Rob Trahms" <[hidden email]>
To: <[hidden email]>
Sent: Friday, July 24, 2009 6:06 AM
Subject: [EVDL] Battery performance change after watering?


>
> Hi all -
> I still consider myself a newbie with regards to battery chemistry.  With
> my
> conversion,  I would semi-regularly eyeball electrolyte levels in my
> US125s
> after charging to make sure they were correct and not in need of topping
> off.  In most cases, the levels looked right and none of the plates were
> exposed, so I didn't mess.  Recently I purchased one of those battery
> fillers with the auto shutoff to help be more exact, and when I used it
> for
> the first time, ALL the cells required water.  I used up about a gallon
> and
> a half of water across 16 of these batteries!  Anyway...
>
> My question is about performance of the batteries after refilling.  Since
> the water levels were apparently low, but not super low, would I notice
> any
> substantial difference in how the batteries perform after topping off?
> Maximum SG difference, or anything like that?  My thought is probably not,
> but I wanted to check with those who have more experience here.
>
> Thanks,
> Rob
>
> -----
> Rob Trahms
> [hidden email]
> Electro - the Cabby-EV
> http://chaosmgmt.blogspot.com chaosmgmt.blogspot.com
>
> --
> View this message in context:
> http://www.nabble.com/Battery-performance-change-after-watering--tp24644196p24644196.html
> Sent from the Electric Vehicle Discussion List mailing list archive at
> Nabble.com.
>
> _______________________________________________
> General EVDL support: http://evdl.org/help/
> Usage guidelines: http://evdl.org/help/index.html#conv
> Archives: http://evdl.org/archive/
> Subscription options: http://lists.sjsu.edu/mailman/listinfo/ev
>
>

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Re: Battery performance change after watering?

SLPinfo.org
Rob,

Interesting timing.  Just this morning I dissembled my pack for the first
time in about a month, cleaned all the batteries and topped up the
water using one of those automatic fill jugs.  I have 10 X 12V batteries and
I probably used about 2/3 of a gallon of distilled water.  Sounds pretty
consistent with what you used.

But I too was wondering if performance would change - didn't notice anything
different in how it drove in this morning; my battery current draw seemed to
be about the same as usual.

- Peter Flipsen Jr
Pocatello, ID
http://www.evalbum.com/1974



On Fri, Jul 24, 2009 at 8:26 AM, Roland Wiench <[hidden email]> wrote:

> Hello Rob,
>
> Adding water to a battery initially, the water being lighter than the acid
> is floating on top of the heaver acid.  Even if a battery has been setting
> for a long time, this same effect happens where the specific gravity at the
> top may be less than the electrolyte at the bottom.
>
> At this time when you use a initially fill battery or use a battery that's
> been idle for a long time, the top portion of the grids has less
> conductance
> then at the bottom. Therefore you have less conductance at the top of the
> plates then you have at the bottom at this time.
>
> It is normal in some high ampere-hour batteries, that when the electrolyte
> level is at the correct level and the water is correctly mix by a finish
> charge, that as it is being discharge, the electrolyte level may drop.
>  Then
> when charging the batteries, this electrolyte will rise.
>
> Just make sure that when you are at the most discharge point that you may
> want to go, the electrolyte level is just about the plates.  If not, then
> add just enough water to get about 1/8 inch above the plates.  Then you
> charge the battery to about 80 to 90 percent and then finish adding the
> water.  Finish charge the battery to 100 percent which at this time will
> give you a better mix of water that is floating on top and the acid at a
> lower level.
>
> The performance is going to depend on the right time and methods you add
> the
> water and getting a proper mix.  You then take a specific gravity reading
> just after the completion of the finish charge.
>
> One gallon per 15 batteries of your size is about right.  I normally use
> one
> gallon per 12 batteries every 6 months discharging the batteries to 80
> percent of charge or 20 Depth of Discharge.  I normally charge the
> batteries
> for 15 minutes at 25 amps each day just before I leave.  This initial high
> battery voltage seems to get me another mile at a lower battery voltage
> than
> if I charge the batteries a day before.
>
> The formula for electrolyte mixing is:
>
> Five parts of water  =  5 x H2O    or  5 x 1.0 SG = 5.0
> Three parts of acid  =  3 x H2SO4  or  3 x 1.8 SG = 5.4
>
> Therefore the average becomes for eight parts = (5.0 + 5.4)/8 = 1.3 SG
>
> When mixing, the 1.3 SG is hot, so when it cools, the final specific
> gravity
> reading will come to 1.277 SG. for 100 percent state of charge.
>
> Roland
>
>
>
>
> ----- Original Message -----
> From: "Rob Trahms" <[hidden email]>
> To: <[hidden email]>
> Sent: Friday, July 24, 2009 6:06 AM
> Subject: [EVDL] Battery performance change after watering?
>
>
> >
> > Hi all -
> > I still consider myself a newbie with regards to battery chemistry.  With
> > my
> > conversion,  I would semi-regularly eyeball electrolyte levels in my
> > US125s
> > after charging to make sure they were correct and not in need of topping
> > off.  In most cases, the levels looked right and none of the plates were
> > exposed, so I didn't mess.  Recently I purchased one of those battery
> > fillers with the auto shutoff to help be more exact, and when I used it
> > for
> > the first time, ALL the cells required water.  I used up about a gallon
> > and
> > a half of water across 16 of these batteries!  Anyway...
> >
> > My question is about performance of the batteries after refilling.  Since
> > the water levels were apparently low, but not super low, would I notice
> > any
> > substantial difference in how the batteries perform after topping off?
> > Maximum SG difference, or anything like that?  My thought is probably
> not,
> > but I wanted to check with those who have more experience here.
> >
> > Thanks,
> > Rob
> >
> > -----
> > Rob Trahms
> > [hidden email]
> > Electro - the Cabby-EV
> > http://chaosmgmt.blogspot.com chaosmgmt.blogspot.com
> >
> > --
> > View this message in context:
> >
> http://www.nabble.com/Battery-performance-change-after-watering--tp24644196p24644196.html
> > Sent from the Electric Vehicle Discussion List mailing list archive at
> > Nabble.com.
> >
> > _______________________________________________
> > General EVDL support: http://evdl.org/help/
> > Usage guidelines: http://evdl.org/help/index.html#conv
> > Archives: http://evdl.org/archive/
> > Subscription options: http://lists.sjsu.edu/mailman/listinfo/ev
> >
> >
>
> _______________________________________________
> General EVDL support: http://evdl.org/help/
> Usage guidelines: http://evdl.org/help/index.html#conv
> Archives: http://evdl.org/archive/
> Subscription options: http://lists.sjsu.edu/mailman/listinfo/ev
>
>
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Experience?: equalization charge causing standing voltage to droop

Chuck Hursch-2
In reply to this post by Roland Wiench
Has anybody else noticed that after doing an equalization charge, that
the standing voltage is lower?  I'm talking 6V floodies here.  My
version of an equalization charge is 6A constant current, looking for
the pack's (or batteries) voltage roll-over (ie. the voltage goes up
till it starts to go down).  My "algorithm" is to equalize charge for a
minimum of two hours, and longer if necessary, to see the voltage
rollover.  I check the voltage every half hour.  In my case, almost
everytime, I see the peak reading at 1/2 hour in (I think that means the
pack is pretty well topped off, but I do it for two hours to allow any
cells that are behind that I can't detect a chance to catch up).  The
batteries will warm up about 8-10 degF through the process, and the peak
voltage reached on my 6-mo-old US2200XCs is ~131-132V on my 96V pack,
with each battery peaking in the range of 8.20-8.25V.  The pack voltage
will drop off about 0.5-1.0V from the peak by the end.  I'd like to know
  how people equalize their 6V floodie packs.

The thing that gets me is that everytime I do this, my standing voltage
after several hours is lower than before, and takes a few days to
recover.  What gets me even more is that the standing voltage for my
new-ish 6V'ers is in the range 6.3-6.4V.  New-ish batteries I've heard
are usually in the range 6.4-6.5V.  My batteries' standing voltage is
more like those of mid-life batteries, but higher than the traditional
100%-charge level given as 6.30V.

And to add further to the aura of ?-marks on my gray matter, I decided
to try moving my constant-voltage setpoint from 118.4V (14.8V/12V, I was
actually closer to 119-120V, but temperature was lower than 77degF) that
I was at for many months (since some felt that the US Battery
recommendation of 7.75V/batt or 2.58Vpc was too high)to this 7.75V/6V
battery.  So what happens?  My specific gravity readings move up :-),
about 10 points.  But, now when I walk out to the carport in the morning
to unplug, that CanPulse light (which is on over ~103V), which usually
was on after having the constant voltage at 118.4V, is now off
everytime.  I think I'm happier at 7.75V.  But this seeming reverse
relationship between standing voltage and hydrometer readings and how
hard the batteries are charged doesn't make sense, and I've been having
troubles with that for several years now - I've seen it across three packs.

I know Lee has said he doesn't put much stock in voltage readings, but
it's a might scary with my current standing voltage readings and the
price of batteries.  I just had a cell go down over the last few weeks,
and it was sitting at 1235sg yesterday, while the rest were tight at
1260-1280 (I still have to make up my spreadsheet to get the actual
numbers).  This pack has been quite good in that dept, till the above
cell started having problems.

So please enlighten me.  What do others do for equalizing?  Should I
drop the equalization charges, or do something different?  I used to do
them weakly, but now do 'em basically monthly, at least several hours
before my monthly hydrometer readings, and I've also started doing it
after I water my batteries at that monthly battery maintenance, to stir
the electrolyte.

I drive about 12.5 miles a day on weekdays, charge overnight at 8.5-9A
DC.  A fair # of steep hills, with the main one being the hill to get
home, where I can usually keep it at 250 battery amps, unless a car is
following me.  I figure the more I can keep the lid at 250A max, the
longer the batteries will last (it's slow coming up that hill, though).

Thanks,
Chuck



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Re: Experience?: equalization charge causing standing voltage todroop

Roland Wiench
Hello Chuck,

I am running Trojan battery pack of 6 volts at 180 volts and my equalization
charge is 7.783 volts or 233.5 volts at 80 F. battery temperature.  I
subtract 0.028 volts per cell for every 10 degrees over 80 F.  I just got
done doing a equalization charge at 228.45 volts because my battery
temperature was just little over a 100 F.

Before I had battery regulators (BMS), I would do a monthly equalize charge
only if any of my battery voltages was 0.002 volt difference. Using the
simple Lee's BMS shunt regulators that are modified with two parallel lamps
and diodes for 6 volts which is on the WEB some place, I need only to charge
at a maximum of 221 volts at a battery temperature of 80 F.

It is normal for the battery voltage to drop after charging.  My battery
pack will drop from the 233 volt equalization charge to 203 volts or about
6.8 volts in less than a minute.  If I let the battery pack set for more
than 12 hours letting it cool, it will come down to between 6.33 to 6.34
volts which is about 99.52 percent of full charge.

For the last 7 years, I have charge this pack at 25 amps at a normal charge
of 222 volts or 7.4 volts per battery.  The 25 amp rating is 10 percent of
the ampere-hour rating of the battery.  I normally like to charge the
batteries in the morning before I leave, because they are cool and can
accept this charge rating.  I normally charge the pack in with 15 minutes.
(Only drive about 5 miles a day)

For a 6 volt battery the 100 percent charge at 77 F. battery temperature is
6.37 volts with a specific gravity reading of 1.277 SG.

Roland




----- Original Message -----
From: "Chuck Hursch" <[hidden email]>
To: "Electric Vehicle Discussion List" <[hidden email]>
Sent: Monday, July 27, 2009 2:25 PM
Subject: [EVDL] Experience?: equalization charge causing standing voltage
todroop


> Has anybody else noticed that after doing an equalization charge, that
> the standing voltage is lower?  I'm talking 6V floodies here.  My
> version of an equalization charge is 6A constant current, looking for
> the pack's (or batteries) voltage roll-over (ie. the voltage goes up
> till it starts to go down).  My "algorithm" is to equalize charge for a
> minimum of two hours, and longer if necessary, to see the voltage
> rollover.  I check the voltage every half hour.  In my case, almost
> everytime, I see the peak reading at 1/2 hour in (I think that means the
> pack is pretty well topped off, but I do it for two hours to allow any
> cells that are behind that I can't detect a chance to catch up).  The
> batteries will warm up about 8-10 degF through the process, and the peak
> voltage reached on my 6-mo-old US2200XCs is ~131-132V on my 96V pack,
> with each battery peaking in the range of 8.20-8.25V.  The pack voltage
> will drop off about 0.5-1.0V from the peak by the end.  I'd like to know
>   how people equalize their 6V floodie packs.
>
> The thing that gets me is that everytime I do this, my standing voltage
> after several hours is lower than before, and takes a few days to
> recover.  What gets me even more is that the standing voltage for my
> new-ish 6V'ers is in the range 6.3-6.4V.  New-ish batteries I've heard
> are usually in the range 6.4-6.5V.  My batteries' standing voltage is
> more like those of mid-life batteries, but higher than the traditional
> 100%-charge level given as 6.30V.
>
> And to add further to the aura of ?-marks on my gray matter, I decided
> to try moving my constant-voltage setpoint from 118.4V (14.8V/12V, I was
> actually closer to 119-120V, but temperature was lower than 77degF) that
> I was at for many months (since some felt that the US Battery
> recommendation of 7.75V/batt or 2.58Vpc was too high)to this 7.75V/6V
> battery.  So what happens?  My specific gravity readings move up :-),
> about 10 points.  But, now when I walk out to the carport in the morning
> to unplug, that CanPulse light (which is on over ~103V), which usually
> was on after having the constant voltage at 118.4V, is now off
> everytime.  I think I'm happier at 7.75V.  But this seeming reverse
> relationship between standing voltage and hydrometer readings and how
> hard the batteries are charged doesn't make sense, and I've been having
> troubles with that for several years now - I've seen it across three
> packs.
>
> I know Lee has said he doesn't put much stock in voltage readings, but
> it's a might scary with my current standing voltage readings and the
> price of batteries.  I just had a cell go down over the last few weeks,
> and it was sitting at 1235sg yesterday, while the rest were tight at
> 1260-1280 (I still have to make up my spreadsheet to get the actual
> numbers).  This pack has been quite good in that dept, till the above
> cell started having problems.
>
> So please enlighten me.  What do others do for equalizing?  Should I
> drop the equalization charges, or do something different?  I used to do
> them weakly, but now do 'em basically monthly, at least several hours
> before my monthly hydrometer readings, and I've also started doing it
> after I water my batteries at that monthly battery maintenance, to stir
> the electrolyte.
>
> I drive about 12.5 miles a day on weekdays, charge overnight at 8.5-9A
> DC.  A fair # of steep hills, with the main one being the hill to get
> home, where I can usually keep it at 250 battery amps, unless a car is
> following me.  I figure the more I can keep the lid at 250A max, the
> longer the batteries will last (it's slow coming up that hill, though).
>
> Thanks,
> Chuck
>
>
>
> _______________________________________________
> General EVDL support: http://evdl.org/help/
> Usage guidelines: http://evdl.org/help/index.html#conv
> Archives: http://evdl.org/archive/
> Subscription options: http://lists.sjsu.edu/mailman/listinfo/ev
>
>

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Re: Experience?: equalization charge causing standing voltage todroop

Barry Oppenheim
In reply to this post by Chuck Hursch-2
Chuck,

I also have the US2200XC's.  I've been charging using the US Battery
recommended algorithm:  constant current till 7.75V/battery then hold at
constant voltage for 2-4 hours.  So for my 144V pack I will charge to
185-186V and hold for two hours.  This results in ~10% more amp hours being
put in then taken out (i.e. if I use 20amp hours I end up putting 22 back
in;  40 out, 44 in; etc).

Eight hours after the charger stops the resting open voltage for the pack is
153V.  This translates to 6.375V/battery.

The pack has been in service for ~5 months and ~1600 miles.  Except for an
"accidental equalization" from a charger malfunction I have not equalized
the pack.  Based on daily half pack voltage readings and monthly individual
battery voltage readings the pack has stayed in balance.  I drive the
vehicle about 10-20 miles most days and charge each evening.

I know that many knowledgable people on the list (Lee Hart and Rich Rudman)
recommend a lower max voltage http://www.evdl.org/pages/hartcharge.html.
And the higher voltage I'm using is probably an equalization each time I
charge.  Despite this I'm continuing with the US Battery algorithm for a few
reasons:

1.  In case a battery goes bad I don't want to void the warranty
2.  It seems to be keeping the batteries balanced
3.  The 10% overage back in seems about right based on a conversation I had
with Rich Rudman

Am I sacrificing battery life in order to keep a balanced pack?  Possibly.
Maybe US Battery intentionally recommends a higher charge finishing voltage
at the expense of cycles in order to avoid having someone reverse a cell.  I
don't know.

With only about 100 cycles on this pack I hopefully won't find out for years
to come!  I'm a newbie at this so take everything I say and do with a large
grain of salt :-)

Barry Oppenheim
New Hope, PA
www.JustAnotherEVConversion.blogspot.com




-----Original Message-----
From: [hidden email] [mailto:[hidden email]]On
Behalf Of Chuck Hursch
Sent: Monday, July 27, 2009 5:25 PM
To: Electric Vehicle Discussion List
Subject: [EVDL] Experience?: equalization charge causing standing
voltage todroop


Has anybody else noticed that after doing an equalization charge, that
the standing voltage is lower?  I'm talking 6V floodies here.  My
version of an equalization charge is 6A constant current, looking for
the pack's (or batteries) voltage roll-over (ie. the voltage goes up
till it starts to go down).  My "algorithm" is to equalize charge for a
minimum of two hours, and longer if necessary, to see the voltage
rollover.  I check the voltage every half hour.  In my case, almost
everytime, I see the peak reading at 1/2 hour in (I think that means the
pack is pretty well topped off, but I do it for two hours to allow any
cells that are behind that I can't detect a chance to catch up).  The
batteries will warm up about 8-10 degF through the process, and the peak
voltage reached on my 6-mo-old US2200XCs is ~131-132V on my 96V pack,
with each battery peaking in the range of 8.20-8.25V.  The pack voltage
will drop off about 0.5-1.0V from the peak by the end.  I'd like to know
  how people equalize their 6V floodie packs.

The thing that gets me is that everytime I do this, my standing voltage
after several hours is lower than before, and takes a few days to
recover.  What gets me even more is that the standing voltage for my
new-ish 6V'ers is in the range 6.3-6.4V.  New-ish batteries I've heard
are usually in the range 6.4-6.5V.  My batteries' standing voltage is
more like those of mid-life batteries, but higher than the traditional
100%-charge level given as 6.30V.

And to add further to the aura of ?-marks on my gray matter, I decided
to try moving my constant-voltage setpoint from 118.4V (14.8V/12V, I was
actually closer to 119-120V, but temperature was lower than 77degF) that
I was at for many months (since some felt that the US Battery
recommendation of 7.75V/batt or 2.58Vpc was too high)to this 7.75V/6V
battery.  So what happens?  My specific gravity readings move up :-),
about 10 points.  But, now when I walk out to the carport in the morning
to unplug, that CanPulse light (which is on over ~103V), which usually
was on after having the constant voltage at 118.4V, is now off
everytime.  I think I'm happier at 7.75V.  But this seeming reverse
relationship between standing voltage and hydrometer readings and how
hard the batteries are charged doesn't make sense, and I've been having
troubles with that for several years now - I've seen it across three packs.

I know Lee has said he doesn't put much stock in voltage readings, but
it's a might scary with my current standing voltage readings and the
price of batteries.  I just had a cell go down over the last few weeks,
and it was sitting at 1235sg yesterday, while the rest were tight at
1260-1280 (I still have to make up my spreadsheet to get the actual
numbers).  This pack has been quite good in that dept, till the above
cell started having problems.

So please enlighten me.  What do others do for equalizing?  Should I
drop the equalization charges, or do something different?  I used to do
them weakly, but now do 'em basically monthly, at least several hours
before my monthly hydrometer readings, and I've also started doing it
after I water my batteries at that monthly battery maintenance, to stir
the electrolyte.

I drive about 12.5 miles a day on weekdays, charge overnight at 8.5-9A
DC.  A fair # of steep hills, with the main one being the hill to get
home, where I can usually keep it at 250 battery amps, unless a car is
following me.  I figure the more I can keep the lid at 250A max, the
longer the batteries will last (it's slow coming up that hill, though).

Thanks,
Chuck



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Usage guidelines: http://evdl.org/help/index.html#conv
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Re: Experience?: equalization charge causing standing voltage todroop

Chuck Hursch-2
In reply to this post by Roland Wiench
Hi Roland,

Yes, I know the voltage drops when you pull the plug.  Still am
wondering whether reduced standing voltage comes from an equalization
charge.  I think it is a fair bet that I change the plate structure
somehow when I give them an overcharge like that.

Chuck

Roland Wiench wrote:

> Hello Chuck,
>
> I am running Trojan battery pack of 6 volts at 180 volts and my equalization
> charge is 7.783 volts or 233.5 volts at 80 F. battery temperature.  I
> subtract 0.028 volts per cell for every 10 degrees over 80 F.  I just got
> done doing a equalization charge at 228.45 volts because my battery
> temperature was just little over a 100 F.
>
> Before I had battery regulators (BMS), I would do a monthly equalize charge
> only if any of my battery voltages was 0.002 volt difference. Using the
> simple Lee's BMS shunt regulators that are modified with two parallel lamps
> and diodes for 6 volts which is on the WEB some place, I need only to charge
> at a maximum of 221 volts at a battery temperature of 80 F.
>
> It is normal for the battery voltage to drop after charging.  My battery
> pack will drop from the 233 volt equalization charge to 203 volts or about
> 6.8 volts in less than a minute.  If I let the battery pack set for more
> than 12 hours letting it cool, it will come down to between 6.33 to 6.34
> volts which is about 99.52 percent of full charge.
>
> For the last 7 years, I have charge this pack at 25 amps at a normal charge
> of 222 volts or 7.4 volts per battery.  The 25 amp rating is 10 percent of
> the ampere-hour rating of the battery.  I normally like to charge the
> batteries in the morning before I leave, because they are cool and can
> accept this charge rating.  I normally charge the pack in with 15 minutes.
> (Only drive about 5 miles a day)
>
> For a 6 volt battery the 100 percent charge at 77 F. battery temperature is
> 6.37 volts with a specific gravity reading of 1.277 SG.
>
> Roland
>
>
>
>
> ----- Original Message -----
> From: "Chuck Hursch" <[hidden email]>
> To: "Electric Vehicle Discussion List" <[hidden email]>
> Sent: Monday, July 27, 2009 2:25 PM
> Subject: [EVDL] Experience?: equalization charge causing standing voltage
> todroop
>
>
>> Has anybody else noticed that after doing an equalization charge, that
>> the standing voltage is lower?  I'm talking 6V floodies here.  My
>> version of an equalization charge is 6A constant current, looking for
>> the pack's (or batteries) voltage roll-over (ie. the voltage goes up
>> till it starts to go down).  My "algorithm" is to equalize charge for a
>> minimum of two hours, and longer if necessary, to see the voltage
>> rollover.  I check the voltage every half hour.  In my case, almost
>> everytime, I see the peak reading at 1/2 hour in (I think that means the
>> pack is pretty well topped off, but I do it for two hours to allow any
>> cells that are behind that I can't detect a chance to catch up).  The
>> batteries will warm up about 8-10 degF through the process, and the peak
>> voltage reached on my 6-mo-old US2200XCs is ~131-132V on my 96V pack,
>> with each battery peaking in the range of 8.20-8.25V.  The pack voltage
>> will drop off about 0.5-1.0V from the peak by the end.  I'd like to know
>>   how people equalize their 6V floodie packs.
>>
>> The thing that gets me is that everytime I do this, my standing voltage
>> after several hours is lower than before, and takes a few days to
>> recover.  What gets me even more is that the standing voltage for my
>> new-ish 6V'ers is in the range 6.3-6.4V.  New-ish batteries I've heard
>> are usually in the range 6.4-6.5V.  My batteries' standing voltage is
>> more like those of mid-life batteries, but higher than the traditional
>> 100%-charge level given as 6.30V.
>>
>> And to add further to the aura of ?-marks on my gray matter, I decided
>> to try moving my constant-voltage setpoint from 118.4V (14.8V/12V, I was
>> actually closer to 119-120V, but temperature was lower than 77degF) that
>> I was at for many months (since some felt that the US Battery
>> recommendation of 7.75V/batt or 2.58Vpc was too high)to this 7.75V/6V
>> battery.  So what happens?  My specific gravity readings move up :-),
>> about 10 points.  But, now when I walk out to the carport in the morning
>> to unplug, that CanPulse light (which is on over ~103V), which usually
>> was on after having the constant voltage at 118.4V, is now off
>> everytime.  I think I'm happier at 7.75V.  But this seeming reverse
>> relationship between standing voltage and hydrometer readings and how
>> hard the batteries are charged doesn't make sense, and I've been having
>> troubles with that for several years now - I've seen it across three
>> packs.
>>
>> I know Lee has said he doesn't put much stock in voltage readings, but
>> it's a might scary with my current standing voltage readings and the
>> price of batteries.  I just had a cell go down over the last few weeks,
>> and it was sitting at 1235sg yesterday, while the rest were tight at
>> 1260-1280 (I still have to make up my spreadsheet to get the actual
>> numbers).  This pack has been quite good in that dept, till the above
>> cell started having problems.
>>
>> So please enlighten me.  What do others do for equalizing?  Should I
>> drop the equalization charges, or do something different?  I used to do
>> them weakly, but now do 'em basically monthly, at least several hours
>> before my monthly hydrometer readings, and I've also started doing it
>> after I water my batteries at that monthly battery maintenance, to stir
>> the electrolyte.
>>
>> I drive about 12.5 miles a day on weekdays, charge overnight at 8.5-9A
>> DC.  A fair # of steep hills, with the main one being the hill to get
>> home, where I can usually keep it at 250 battery amps, unless a car is
>> following me.  I figure the more I can keep the lid at 250A max, the
>> longer the batteries will last (it's slow coming up that hill, though).
>>
>> Thanks,
>> Chuck
>>
>>
>>
>> _______________________________________________
>> General EVDL support: http://evdl.org/help/
>> Usage guidelines: http://evdl.org/help/index.html#conv
>> Archives: http://evdl.org/archive/
>> Subscription options: http://lists.sjsu.edu/mailman/listinfo/ev
>>
>>
>
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>


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Re: Experience?: equalization charge causing standing voltage todroop

Chuck Hursch-2
In reply to this post by Barry Oppenheim
Hi Barry,

Your standing voltages are about where mine are at.  So at least I'm not
the only one with new-ish batteries in the high 6.30s.  I have about 7
months on mine, and about the same number of miles.  Are you liking your
battery pack - do they seem to hold up well under use?

Chuck

Barry Oppenheim wrote:

> Chuck,
>
> I also have the US2200XC's.  I've been charging using the US Battery
> recommended algorithm:  constant current till 7.75V/battery then hold at
> constant voltage for 2-4 hours.  So for my 144V pack I will charge to
> 185-186V and hold for two hours.  This results in ~10% more amp hours being
> put in then taken out (i.e. if I use 20amp hours I end up putting 22 back
> in;  40 out, 44 in; etc).
>
> Eight hours after the charger stops the resting open voltage for the pack is
> 153V.  This translates to 6.375V/battery.
>
> The pack has been in service for ~5 months and ~1600 miles.  Except for an
> "accidental equalization" from a charger malfunction I have not equalized
> the pack.  Based on daily half pack voltage readings and monthly individual
> battery voltage readings the pack has stayed in balance.  I drive the
> vehicle about 10-20 miles most days and charge each evening.
>
> I know that many knowledgable people on the list (Lee Hart and Rich Rudman)
> recommend a lower max voltage http://www.evdl.org/pages/hartcharge.html.
> And the higher voltage I'm using is probably an equalization each time I
> charge.  Despite this I'm continuing with the US Battery algorithm for a few
> reasons:
>
> 1.  In case a battery goes bad I don't want to void the warranty
> 2.  It seems to be keeping the batteries balanced
> 3.  The 10% overage back in seems about right based on a conversation I had
> with Rich Rudman
>
> Am I sacrificing battery life in order to keep a balanced pack?  Possibly.
> Maybe US Battery intentionally recommends a higher charge finishing voltage
> at the expense of cycles in order to avoid having someone reverse a cell.  I
> don't know.
>
> With only about 100 cycles on this pack I hopefully won't find out for years
> to come!  I'm a newbie at this so take everything I say and do with a large
> grain of salt :-)
>
> Barry Oppenheim
> New Hope, PA
> www.JustAnotherEVConversion.blogspot.com
>
>
>
>
> -----Original Message-----
> From: [hidden email] [mailto:[hidden email]]On
> Behalf Of Chuck Hursch
> Sent: Monday, July 27, 2009 5:25 PM
> To: Electric Vehicle Discussion List
> Subject: [EVDL] Experience?: equalization charge causing standing
> voltage todroop
>
>
> Has anybody else noticed that after doing an equalization charge, that
> the standing voltage is lower?  I'm talking 6V floodies here.  My
> version of an equalization charge is 6A constant current, looking for
> the pack's (or batteries) voltage roll-over (ie. the voltage goes up
> till it starts to go down).  My "algorithm" is to equalize charge for a
> minimum of two hours, and longer if necessary, to see the voltage
> rollover.  I check the voltage every half hour.  In my case, almost
> everytime, I see the peak reading at 1/2 hour in (I think that means the
> pack is pretty well topped off, but I do it for two hours to allow any
> cells that are behind that I can't detect a chance to catch up).  The
> batteries will warm up about 8-10 degF through the process, and the peak
> voltage reached on my 6-mo-old US2200XCs is ~131-132V on my 96V pack,
> with each battery peaking in the range of 8.20-8.25V.  The pack voltage
> will drop off about 0.5-1.0V from the peak by the end.  I'd like to know
>   how people equalize their 6V floodie packs.
>
> The thing that gets me is that everytime I do this, my standing voltage
> after several hours is lower than before, and takes a few days to
> recover.  What gets me even more is that the standing voltage for my
> new-ish 6V'ers is in the range 6.3-6.4V.  New-ish batteries I've heard
> are usually in the range 6.4-6.5V.  My batteries' standing voltage is
> more like those of mid-life batteries, but higher than the traditional
> 100%-charge level given as 6.30V.
>
> And to add further to the aura of ?-marks on my gray matter, I decided
> to try moving my constant-voltage setpoint from 118.4V (14.8V/12V, I was
> actually closer to 119-120V, but temperature was lower than 77degF) that
> I was at for many months (since some felt that the US Battery
> recommendation of 7.75V/batt or 2.58Vpc was too high)to this 7.75V/6V
> battery.  So what happens?  My specific gravity readings move up :-),
> about 10 points.  But, now when I walk out to the carport in the morning
> to unplug, that CanPulse light (which is on over ~103V), which usually
> was on after having the constant voltage at 118.4V, is now off
> everytime.  I think I'm happier at 7.75V.  But this seeming reverse
> relationship between standing voltage and hydrometer readings and how
> hard the batteries are charged doesn't make sense, and I've been having
> troubles with that for several years now - I've seen it across three packs.
>
> I know Lee has said he doesn't put much stock in voltage readings, but
> it's a might scary with my current standing voltage readings and the
> price of batteries.  I just had a cell go down over the last few weeks,
> and it was sitting at 1235sg yesterday, while the rest were tight at
> 1260-1280 (I still have to make up my spreadsheet to get the actual
> numbers).  This pack has been quite good in that dept, till the above
> cell started having problems.
>
> So please enlighten me.  What do others do for equalizing?  Should I
> drop the equalization charges, or do something different?  I used to do
> them weakly, but now do 'em basically monthly, at least several hours
> before my monthly hydrometer readings, and I've also started doing it
> after I water my batteries at that monthly battery maintenance, to stir
> the electrolyte.
>
> I drive about 12.5 miles a day on weekdays, charge overnight at 8.5-9A
> DC.  A fair # of steep hills, with the main one being the hill to get
> home, where I can usually keep it at 250 battery amps, unless a car is
> following me.  I figure the more I can keep the lid at 250A max, the
> longer the batteries will last (it's slow coming up that hill, though).
>
> Thanks,
> Chuck
>
>
>
> _______________________________________________
> General EVDL support: http://evdl.org/help/
> Usage guidelines: http://evdl.org/help/index.html#conv
> Archives: http://evdl.org/archive/
> Subscription options: http://lists.sjsu.edu/mailman/listinfo/ev
>
>
> No virus found in this incoming message.
> Checked by AVG - www.avg.com
> Version: 8.5.392 / Virus Database: 270.13.32/2266 - Release Date: 07/27/09
> 05:58:00
>
> _______________________________________________
> General EVDL support: http://evdl.org/help/
> Usage guidelines: http://evdl.org/help/index.html#conv
> Archives: http://evdl.org/archive/
> Subscription options: http://lists.sjsu.edu/mailman/listinfo/ev
>
>


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Re: Experience?: equalization charge causing standing voltage todroop

Barry Oppenheim
Chuck,

So far the pack has been good to me (knock on wood, or lead in this case).
I use and charge it everyday.  I rarely take it below 50% SOC.  I also limit
the battery amp draw to 350A.

My daily drive has a few steep hills that require 300-350A draws for 5-20
seconds.  In order to accomplish this with acceptable speed I have my
controller battery voltage limits set lower than most on the list recommend.
I'm using 1.5V/cell(108V) as a lower cutoff.  Most on the list (especially
the ones with experience and a lot smarter than me) would recommend
1.75V/cell(126V) as the lower limit.

I found that the higher cutoff voltage setting limited performance
(acceleration, hills) too much.  The lower limit seems to work better for
me.  And since the pack is mostly at a higher SOC and well balanced I think
the chances of reversing a cell are low.

Even with the cutoff at 108V I've yet to see the voltage drop to anywhere
near that low.  With a 350A draw, end of the trip hill, the voltage at most
will drop to 115V-120V.  Only time will tell.

Barry Oppenheim
New Hope, PA
www.JustAnotherEVConversion.blogspot.com

-----Original Message-----
From: [hidden email] [mailto:[hidden email]]On
Behalf Of Chuck Hursch
Sent: Tuesday, July 28, 2009 5:45 PM
To: Electric Vehicle Discussion List
Subject: Re: [EVDL] Experience?: equalization charge causing standing
voltage todroop


Hi Barry,

Your standing voltages are about where mine are at.  So at least I'm not
the only one with new-ish batteries in the high 6.30s.  I have about 7
months on mine, and about the same number of miles.  Are you liking your
battery pack - do they seem to hold up well under use?

Chuck

Barry Oppenheim wrote:
> Chuck,
>
> I also have the US2200XC's.  I've been charging using the US Battery
> recommended algorithm:  constant current till 7.75V/battery then hold at
> constant voltage for 2-4 hours.  So for my 144V pack I will charge to
> 185-186V and hold for two hours.  This results in ~10% more amp hours
being
> put in then taken out (i.e. if I use 20amp hours I end up putting 22 back
> in;  40 out, 44 in; etc).
>
> Eight hours after the charger stops the resting open voltage for the pack
is
> 153V.  This translates to 6.375V/battery.
>
> The pack has been in service for ~5 months and ~1600 miles.  Except for an
> "accidental equalization" from a charger malfunction I have not equalized
> the pack.  Based on daily half pack voltage readings and monthly
individual
> battery voltage readings the pack has stayed in balance.  I drive the
> vehicle about 10-20 miles most days and charge each evening.
>
> I know that many knowledgable people on the list (Lee Hart and Rich
Rudman)
> recommend a lower max voltage http://www.evdl.org/pages/hartcharge.html.
> And the higher voltage I'm using is probably an equalization each time I
> charge.  Despite this I'm continuing with the US Battery algorithm for a
few
> reasons:
>
> 1.  In case a battery goes bad I don't want to void the warranty
> 2.  It seems to be keeping the batteries balanced
> 3.  The 10% overage back in seems about right based on a conversation I
had
> with Rich Rudman
>
> Am I sacrificing battery life in order to keep a balanced pack?  Possibly.
> Maybe US Battery intentionally recommends a higher charge finishing
voltage
> at the expense of cycles in order to avoid having someone reverse a cell.
I
> don't know.
>
> With only about 100 cycles on this pack I hopefully won't find out for
years
> to come!  I'm a newbie at this so take everything I say and do with a
large

> grain of salt :-)
>
> Barry Oppenheim
> New Hope, PA
> www.JustAnotherEVConversion.blogspot.com
>
>
>
>
> -----Original Message-----
> From: [hidden email] [mailto:[hidden email]]On
> Behalf Of Chuck Hursch
> Sent: Monday, July 27, 2009 5:25 PM
> To: Electric Vehicle Discussion List
> Subject: [EVDL] Experience?: equalization charge causing standing
> voltage todroop
>
>
> Has anybody else noticed that after doing an equalization charge, that
> the standing voltage is lower?  I'm talking 6V floodies here.  My
> version of an equalization charge is 6A constant current, looking for
> the pack's (or batteries) voltage roll-over (ie. the voltage goes up
> till it starts to go down).  My "algorithm" is to equalize charge for a
> minimum of two hours, and longer if necessary, to see the voltage
> rollover.  I check the voltage every half hour.  In my case, almost
> everytime, I see the peak reading at 1/2 hour in (I think that means the
> pack is pretty well topped off, but I do it for two hours to allow any
> cells that are behind that I can't detect a chance to catch up).  The
> batteries will warm up about 8-10 degF through the process, and the peak
> voltage reached on my 6-mo-old US2200XCs is ~131-132V on my 96V pack,
> with each battery peaking in the range of 8.20-8.25V.  The pack voltage
> will drop off about 0.5-1.0V from the peak by the end.  I'd like to know
>   how people equalize their 6V floodie packs.
>
> The thing that gets me is that everytime I do this, my standing voltage
> after several hours is lower than before, and takes a few days to
> recover.  What gets me even more is that the standing voltage for my
> new-ish 6V'ers is in the range 6.3-6.4V.  New-ish batteries I've heard
> are usually in the range 6.4-6.5V.  My batteries' standing voltage is
> more like those of mid-life batteries, but higher than the traditional
> 100%-charge level given as 6.30V.
>
> And to add further to the aura of ?-marks on my gray matter, I decided
> to try moving my constant-voltage setpoint from 118.4V (14.8V/12V, I was
> actually closer to 119-120V, but temperature was lower than 77degF) that
> I was at for many months (since some felt that the US Battery
> recommendation of 7.75V/batt or 2.58Vpc was too high)to this 7.75V/6V
> battery.  So what happens?  My specific gravity readings move up :-),
> about 10 points.  But, now when I walk out to the carport in the morning
> to unplug, that CanPulse light (which is on over ~103V), which usually
> was on after having the constant voltage at 118.4V, is now off
> everytime.  I think I'm happier at 7.75V.  But this seeming reverse
> relationship between standing voltage and hydrometer readings and how
> hard the batteries are charged doesn't make sense, and I've been having
> troubles with that for several years now - I've seen it across three
packs.

>
> I know Lee has said he doesn't put much stock in voltage readings, but
> it's a might scary with my current standing voltage readings and the
> price of batteries.  I just had a cell go down over the last few weeks,
> and it was sitting at 1235sg yesterday, while the rest were tight at
> 1260-1280 (I still have to make up my spreadsheet to get the actual
> numbers).  This pack has been quite good in that dept, till the above
> cell started having problems.
>
> So please enlighten me.  What do others do for equalizing?  Should I
> drop the equalization charges, or do something different?  I used to do
> them weakly, but now do 'em basically monthly, at least several hours
> before my monthly hydrometer readings, and I've also started doing it
> after I water my batteries at that monthly battery maintenance, to stir
> the electrolyte.
>
> I drive about 12.5 miles a day on weekdays, charge overnight at 8.5-9A
> DC.  A fair # of steep hills, with the main one being the hill to get
> home, where I can usually keep it at 250 battery amps, unless a car is
> following me.  I figure the more I can keep the lid at 250A max, the
> longer the batteries will last (it's slow coming up that hill, though).
>
> Thanks,
> Chuck
>
>
>
> _______________________________________________
> General EVDL support: http://evdl.org/help/
> Usage guidelines: http://evdl.org/help/index.html#conv
> Archives: http://evdl.org/archive/
> Subscription options: http://lists.sjsu.edu/mailman/listinfo/ev
>
>
> No virus found in this incoming message.
> Checked by AVG - www.avg.com
> Version: 8.5.392 / Virus Database: 270.13.32/2266 - Release Date: 07/27/09
> 05:58:00
>
> _______________________________________________
> General EVDL support: http://evdl.org/help/
> Usage guidelines: http://evdl.org/help/index.html#conv
> Archives: http://evdl.org/archive/
> Subscription options: http://lists.sjsu.edu/mailman/listinfo/ev
>
>


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No virus found in this incoming message.
Checked by AVG - www.avg.com
Version: 8.5.392 / Virus Database: 270.13.34/2268 - Release Date: 07/28/09
06:00:00

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Re: Experience?: equalization charge causing standing voltage todroop

Chuck Hursch-2
Barry,

Thanks for recounting your experiences.

I wanted to know how fast you charge your pack, what charger, and what
AC source you have (120V or 240V).  I have a 15A limit on 120V gear, so
that means right now I'm bulk charging at 8.5-9A (kinda slow), and I'd
like to move that up to 12A or thereabouts.  Zivan K2.  US Battery
recommends C/10 bulk charging rate, so about 23A.

Yeah, I'm trying to limit the battery current draw to 250A, and am
largely successful in doing so.  I have had a number of battery wizards
tell me that 6V floodies like these will last longer with a ceiling of
250A.  It really crawls coming back up my steep hill at 250A, about
11-12mph.  I am usually coming back home fairly late in the evening, so
there is not much traffic. My rule is that coming up the hill, if nobody
is following me (and can't see any headlights coming up around the
corner behind me), once I hit that grade and things settle in at 250A,
that's where it is staying, follower or not (unless it was an emergency
vehicle, of course - the road is narrow with no pull-off, although I
could probably saddle up to the side).  If somebody is following me,
well, then it's put the peddle down pretty much all the way for 350A and
do 17-18mph.  Speed limit is 25mph, although even with my gas vehicle I
won't usually go that fast, since it's a narrow road with a curve and
lots of bushes for deer to hide in.

Well, for instance, yesterday my charge did not complete, since the
timer shut down at 7AM at the end of the TOU off-peak period from the
electrical utility.  I think the pack had hit its constant voltage
stage, but wasn't there for long.  Voltages were higher on the trip than
if the pack had been sitting for a few hours at that constant voltage
level - at least that's the way it seems.  I really don't understand
that.  I think the surface structure of the plates must change somehow
if they are held at a high voltage for very long - whether it's damaging
I'm trying to find out.

Thanks,
Chuck

Barry Oppenheim wrote:

> Chuck,
>
> So far the pack has been good to me (knock on wood, or lead in this case).
> I use and charge it everyday.  I rarely take it below 50% SOC.  I also limit
> the battery amp draw to 350A.
>
> My daily drive has a few steep hills that require 300-350A draws for 5-20
> seconds.  In order to accomplish this with acceptable speed I have my
> controller battery voltage limits set lower than most on the list recommend.
> I'm using 1.5V/cell(108V) as a lower cutoff.  Most on the list (especially
> the ones with experience and a lot smarter than me) would recommend
> 1.75V/cell(126V) as the lower limit.
>
> I found that the higher cutoff voltage setting limited performance
> (acceleration, hills) too much.  The lower limit seems to work better for
> me.  And since the pack is mostly at a higher SOC and well balanced I think
> the chances of reversing a cell are low.
>
> Even with the cutoff at 108V I've yet to see the voltage drop to anywhere
> near that low.  With a 350A draw, end of the trip hill, the voltage at most
> will drop to 115V-120V.  Only time will tell.
>
> Barry Oppenheim
> New Hope, PA
> www.JustAnotherEVConversion.blogspot.com
>
> -----Original Message-----
> From: [hidden email] [mailto:[hidden email]]On
> Behalf Of Chuck Hursch
> Sent: Tuesday, July 28, 2009 5:45 PM
> To: Electric Vehicle Discussion List
> Subject: Re: [EVDL] Experience?: equalization charge causing standing
> voltage todroop
>
>
> Hi Barry,
>
> Your standing voltages are about where mine are at.  So at least I'm not
> the only one with new-ish batteries in the high 6.30s.  I have about 7
> months on mine, and about the same number of miles.  Are you liking your
> battery pack - do they seem to hold up well under use?
>
> Chuck
>
> Barry Oppenheim wrote:
>> Chuck,
>>
>> I also have the US2200XC's.  I've been charging using the US Battery
>> recommended algorithm:  constant current till 7.75V/battery then hold at
>> constant voltage for 2-4 hours.  So for my 144V pack I will charge to
>> 185-186V and hold for two hours.  This results in ~10% more amp hours
> being
>> put in then taken out (i.e. if I use 20amp hours I end up putting 22 back
>> in;  40 out, 44 in; etc).
>>
>> Eight hours after the charger stops the resting open voltage for the pack
> is
>> 153V.  This translates to 6.375V/battery.
>>
>> The pack has been in service for ~5 months and ~1600 miles.  Except for an
>> "accidental equalization" from a charger malfunction I have not equalized
>> the pack.  Based on daily half pack voltage readings and monthly
> individual
>> battery voltage readings the pack has stayed in balance.  I drive the
>> vehicle about 10-20 miles most days and charge each evening.
>>
>> I know that many knowledgable people on the list (Lee Hart and Rich
> Rudman)
>> recommend a lower max voltage http://www.evdl.org/pages/hartcharge.html.
>> And the higher voltage I'm using is probably an equalization each time I
>> charge.  Despite this I'm continuing with the US Battery algorithm for a
> few
>> reasons:
>>
>> 1.  In case a battery goes bad I don't want to void the warranty
>> 2.  It seems to be keeping the batteries balanced
>> 3.  The 10% overage back in seems about right based on a conversation I
> had
>> with Rich Rudman
>>
>> Am I sacrificing battery life in order to keep a balanced pack?  Possibly.
>> Maybe US Battery intentionally recommends a higher charge finishing
> voltage
>> at the expense of cycles in order to avoid having someone reverse a cell.
> I
>> don't know.
>>
>> With only about 100 cycles on this pack I hopefully won't find out for
> years
>> to come!  I'm a newbie at this so take everything I say and do with a
> large
>> grain of salt :-)
>>
>> Barry Oppenheim
>> New Hope, PA
>> www.JustAnotherEVConversion.blogspot.com
>>
>>
>>
>>
>> -----Original Message-----
>> From: [hidden email] [mailto:[hidden email]]On
>> Behalf Of Chuck Hursch
>> Sent: Monday, July 27, 2009 5:25 PM
>> To: Electric Vehicle Discussion List
>> Subject: [EVDL] Experience?: equalization charge causing standing
>> voltage todroop
>>
>>
>> Has anybody else noticed that after doing an equalization charge, that
>> the standing voltage is lower?  I'm talking 6V floodies here.  My
>> version of an equalization charge is 6A constant current, looking for
>> the pack's (or batteries) voltage roll-over (ie. the voltage goes up
>> till it starts to go down).  My "algorithm" is to equalize charge for a
>> minimum of two hours, and longer if necessary, to see the voltage
>> rollover.  I check the voltage every half hour.  In my case, almost
>> everytime, I see the peak reading at 1/2 hour in (I think that means the
>> pack is pretty well topped off, but I do it for two hours to allow any
>> cells that are behind that I can't detect a chance to catch up).  The
>> batteries will warm up about 8-10 degF through the process, and the peak
>> voltage reached on my 6-mo-old US2200XCs is ~131-132V on my 96V pack,
>> with each battery peaking in the range of 8.20-8.25V.  The pack voltage
>> will drop off about 0.5-1.0V from the peak by the end.  I'd like to know
>>   how people equalize their 6V floodie packs.
>>
>> The thing that gets me is that everytime I do this, my standing voltage
>> after several hours is lower than before, and takes a few days to
>> recover.  What gets me even more is that the standing voltage for my
>> new-ish 6V'ers is in the range 6.3-6.4V.  New-ish batteries I've heard
>> are usually in the range 6.4-6.5V.  My batteries' standing voltage is
>> more like those of mid-life batteries, but higher than the traditional
>> 100%-charge level given as 6.30V.
>>
>> And to add further to the aura of ?-marks on my gray matter, I decided
>> to try moving my constant-voltage setpoint from 118.4V (14.8V/12V, I was
>> actually closer to 119-120V, but temperature was lower than 77degF) that
>> I was at for many months (since some felt that the US Battery
>> recommendation of 7.75V/batt or 2.58Vpc was too high)to this 7.75V/6V
>> battery.  So what happens?  My specific gravity readings move up :-),
>> about 10 points.  But, now when I walk out to the carport in the morning
>> to unplug, that CanPulse light (which is on over ~103V), which usually
>> was on after having the constant voltage at 118.4V, is now off
>> everytime.  I think I'm happier at 7.75V.  But this seeming reverse
>> relationship between standing voltage and hydrometer readings and how
>> hard the batteries are charged doesn't make sense, and I've been having
>> troubles with that for several years now - I've seen it across three
> packs.
>> I know Lee has said he doesn't put much stock in voltage readings, but
>> it's a might scary with my current standing voltage readings and the
>> price of batteries.  I just had a cell go down over the last few weeks,
>> and it was sitting at 1235sg yesterday, while the rest were tight at
>> 1260-1280 (I still have to make up my spreadsheet to get the actual
>> numbers).  This pack has been quite good in that dept, till the above
>> cell started having problems.
>>
>> So please enlighten me.  What do others do for equalizing?  Should I
>> drop the equalization charges, or do something different?  I used to do
>> them weakly, but now do 'em basically monthly, at least several hours
>> before my monthly hydrometer readings, and I've also started doing it
>> after I water my batteries at that monthly battery maintenance, to stir
>> the electrolyte.
>>
>> I drive about 12.5 miles a day on weekdays, charge overnight at 8.5-9A
>> DC.  A fair # of steep hills, with the main one being the hill to get
>> home, where I can usually keep it at 250 battery amps, unless a car is
>> following me.  I figure the more I can keep the lid at 250A max, the
>> longer the batteries will last (it's slow coming up that hill, though).
>>
>> Thanks,
>> Chuck
>>
>>
>>
>> _______________________________________________
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>> Usage guidelines: http://evdl.org/help/index.html#conv
>> Archives: http://evdl.org/archive/
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>>
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>> 05:58:00
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>>
>>
>
>
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> 06:00:00
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>


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Re: Experience?: equalization chargecausing standing voltage todroop

Barry Oppenheim
Chuck,

I'm charging with a PFC20. The outlet is a 20 amp, 110V nominal (122-124V actual), GFI protected circuit. Based on my Evision I'm drawing 2.0 to 2.2 kW/hr.   That translates to 18 amps on the outlet side.  On the battery side the current is 12-15A for the constant current phase.

For a 20 mile trip I use about 8kW. For the entire charge cycle that takes about 6 hours to charge.

I think you are on the conservative side for your max amp draw. Given that your pack is at a relatively high SOC at the end of your commute I would think 350A max is OK.  Lee Hart has a nice table in the archives with max amp draws. for flooded lead acids you can go a 400A in short bursts.

Barry Oppenheim
New Hope, PA
www.JustAnotherEVConversion.blogspot.com

-----Original Message-----
From: Chuck Hursch <[hidden email]>

Date: Wed, 29 Jul 2009 12:24:12
To: Electric Vehicle Discussion List<[hidden email]>
Subject: Re: [EVDL] Experience?: equalization charge
 causing standing voltage todroop


Barry,

Thanks for recounting your experiences.

I wanted to know how fast you charge your pack, what charger, and what
AC source you have (120V or 240V).  I have a 15A limit on 120V gear, so
that means right now I'm bulk charging at 8.5-9A (kinda slow), and I'd
like to move that up to 12A or thereabouts.  Zivan K2.  US Battery
recommends C/10 bulk charging rate, so about 23A.

Yeah, I'm trying to limit the battery current draw to 250A, and am
largely successful in doing so.  I have had a number of battery wizards
tell me that 6V floodies like these will last longer with a ceiling of
250A.  It really crawls coming back up my steep hill at 250A, about
11-12mph.  I am usually coming back home fairly late in the evening, so
there is not much traffic. My rule is that coming up the hill, if nobody
is following me (and can't see any headlights coming up around the
corner behind me), once I hit that grade and things settle in at 250A,
that's where it is staying, follower or not (unless it was an emergency
vehicle, of course - the road is narrow with no pull-off, although I
could probably saddle up to the side).  If somebody is following me,
well, then it's put the peddle down pretty much all the way for 350A and
do 17-18mph.  Speed limit is 25mph, although even with my gas vehicle I
won't usually go that fast, since it's a narrow road with a curve and
lots of bushes for deer to hide in.

Well, for instance, yesterday my charge did not complete, since the
timer shut down at 7AM at the end of the TOU off-peak period from the
electrical utility.  I think the pack had hit its constant voltage
stage, but wasn't there for long.  Voltages were higher on the trip than
if the pack had been sitting for a few hours at that constant voltage
level - at least that's the way it seems.  I really don't understand
that.  I think the surface structure of the plates must change somehow
if they are held at a high voltage for very long - whether it's damaging
I'm trying to find out.

Thanks,
Chuck

Barry Oppenheim wrote:

> Chuck,
>
> So far the pack has been good to me (knock on wood, or lead in this case).
> I use and charge it everyday.  I rarely take it below 50% SOC.  I also limit
> the battery amp draw to 350A.
>
> My daily drive has a few steep hills that require 300-350A draws for 5-20
> seconds.  In order to accomplish this with acceptable speed I have my
> controller battery voltage limits set lower than most on the list recommend.
> I'm using 1.5V/cell(108V) as a lower cutoff.  Most on the list (especially
> the ones with experience and a lot smarter than me) would recommend
> 1.75V/cell(126V) as the lower limit.
>
> I found that the higher cutoff voltage setting limited performance
> (acceleration, hills) too much.  The lower limit seems to work better for
> me.  And since the pack is mostly at a higher SOC and well balanced I think
> the chances of reversing a cell are low.
>
> Even with the cutoff at 108V I've yet to see the voltage drop to anywhere
> near that low.  With a 350A draw, end of the trip hill, the voltage at most
> will drop to 115V-120V.  Only time will tell.
>
> Barry Oppenheim
> New Hope, PA
> www.JustAnotherEVConversion.blogspot.com
>
> -----Original Message-----
> From: [hidden email] [mailto:[hidden email]]On
> Behalf Of Chuck Hursch
> Sent: Tuesday, July 28, 2009 5:45 PM
> To: Electric Vehicle Discussion List
> Subject: Re: [EVDL] Experience?: equalization charge causing standing
> voltage todroop
>
>
> Hi Barry,
>
> Your standing voltages are about where mine are at.  So at least I'm not
> the only one with new-ish batteries in the high 6.30s.  I have about 7
> months on mine, and about the same number of miles.  Are you liking your
> battery pack - do they seem to hold up well under use?
>
> Chuck
>
> Barry Oppenheim wrote:
>> Chuck,
>>
>> I also have the US2200XC's.  I've been charging using the US Battery
>> recommended algorithm:  constant current till 7.75V/battery then hold at
>> constant voltage for 2-4 hours.  So for my 144V pack I will charge to
>> 185-186V and hold for two hours.  This results in ~10% more amp hours
> being
>> put in then taken out (i.e. if I use 20amp hours I end up putting 22 back
>> in;  40 out, 44 in; etc).
>>
>> Eight hours after the charger stops the resting open voltage for the pack
> is
>> 153V.  This translates to 6.375V/battery.
>>
>> The pack has been in service for ~5 months and ~1600 miles.  Except for an
>> "accidental equalization" from a charger malfunction I have not equalized
>> the pack.  Based on daily half pack voltage readings and monthly
> individual
>> battery voltage readings the pack has stayed in balance.  I drive the
>> vehicle about 10-20 miles most days and charge each evening.
>>
>> I know that many knowledgable people on the list (Lee Hart and Rich
> Rudman)
>> recommend a lower max voltage http://www.evdl.org/pages/hartcharge.html.
>> And the higher voltage I'm using is probably an equalization each time I
>> charge.  Despite this I'm continuing with the US Battery algorithm for a
> few
>> reasons:
>>
>> 1.  In case a battery goes bad I don't want to void the warranty
>> 2.  It seems to be keeping the batteries balanced
>> 3.  The 10% overage back in seems about right based on a conversation I
> had
>> with Rich Rudman
>>
>> Am I sacrificing battery life in order to keep a balanced pack?  Possibly.
>> Maybe US Battery intentionally recommends a higher charge finishing
> voltage
>> at the expense of cycles in order to avoid having someone reverse a cell.
> I
>> don't know.
>>
>> With only about 100 cycles on this pack I hopefully won't find out for
> years
>> to come!  I'm a newbie at this so take everything I say and do with a
> large
>> grain of salt :-)
>>
>> Barry Oppenheim
>> New Hope, PA
>> www.JustAnotherEVConversion.blogspot.com
>>
>>
>>
>>
>> -----Original Message-----
>> From: [hidden email] [mailto:[hidden email]]On
>> Behalf Of Chuck Hursch
>> Sent: Monday, July 27, 2009 5:25 PM
>> To: Electric Vehicle Discussion List
>> Subject: [EVDL] Experience?: equalization charge causing standing
>> voltage todroop
>>
>>
>> Has anybody else noticed that after doing an equalization charge, that
>> the standing voltage is lower?  I'm talking 6V floodies here.  My
>> version of an equalization charge is 6A constant current, looking for
>> the pack's (or batteries) voltage roll-over (ie. the voltage goes up
>> till it starts to go down).  My "algorithm" is to equalize charge for a
>> minimum of two hours, and longer if necessary, to see the voltage
>> rollover.  I check the voltage every half hour.  In my case, almost
>> everytime, I see the peak reading at 1/2 hour in (I think that means the
>> pack is pretty well topped off, but I do it for two hours to allow any
>> cells that are behind that I can't detect a chance to catch up).  The
>> batteries will warm up about 8-10 degF through the process, and the peak
>> voltage reached on my 6-mo-old US2200XCs is ~131-132V on my 96V pack,
>> with each battery peaking in the range of 8.20-8.25V.  The pack voltage
>> will drop off about 0.5-1.0V from the peak by the end.  I'd like to know
>>   how people equalize their 6V floodie packs.
>>
>> The thing that gets me is that everytime I do this, my standing voltage
>> after several hours is lower than before, and takes a few days to
>> recover.  What gets me even more is that the standing voltage for my
>> new-ish 6V'ers is in the range 6.3-6.4V.  New-ish batteries I've heard
>> are usually in the range 6.4-6.5V.  My batteries' standing voltage is
>> more like those of mid-life batteries, but higher than the traditional
>> 100%-charge level given as 6.30V.
>>
>> And to add further to the aura of ?-marks on my gray matter, I decided
>> to try moving my constant-voltage setpoint from 118.4V (14.8V/12V, I was
>> actually closer to 119-120V, but temperature was lower than 77degF) that
>> I was at for many months (since some felt that the US Battery
>> recommendation of 7.75V/batt or 2.58Vpc was too high)to this 7.75V/6V
>> battery.  So what happens?  My specific gravity readings move up :-),
>> about 10 points.  But, now when I walk out to the carport in the morning
>> to unplug, that CanPulse light (which is on over ~103V), which usually
>> was on after having the constant voltage at 118.4V, is now off
>> everytime.  I think I'm happier at 7.75V.  But this seeming reverse
>> relationship between standing voltage and hydrometer readings and how
>> hard the batteries are charged doesn't make sense, and I've been having
>> troubles with that for several years now - I've seen it across three
> packs.
>> I know Lee has said he doesn't put much stock in voltage readings, but
>> it's a might scary with my current standing voltage readings and the
>> price of batteries.  I just had a cell go down over the last few weeks,
>> and it was sitting at 1235sg yesterday, while the rest were tight at
>> 1260-1280 (I still have to make up my spreadsheet to get the actual
>> numbers).  This pack has been quite good in that dept, till the above
>> cell started having problems.
>>
>> So please enlighten me.  What do others do for equalizing?  Should I
>> drop the equalization charges, or do something different?  I used to do
>> them weakly, but now do 'em basically monthly, at least several hours
>> before my monthly hydrometer readings, and I've also started doing it
>> after I water my batteries at that monthly battery maintenance, to stir
>> the electrolyte.
>>
>> I drive about 12.5 miles a day on weekdays, charge overnight at 8.5-9A
>> DC.  A fair # of steep hills, with the main one being the hill to get
>> home, where I can usually keep it at 250 battery amps, unless a car is
>> following me.  I figure the more I can keep the lid at 250A max, the
>> longer the batteries will last (it's slow coming up that hill, though).
>>
>> Thanks,
>> Chuck
>>
>>
>>
>> _______________________________________________
>> General EVDL support: http://evdl.org/help/
>> Usage guidelines: http://evdl.org/help/index.html#conv
>> Archives: http://evdl.org/archive/
>> Subscription options: http://lists.sjsu.edu/mailman/listinfo/ev
>>
>>
>> No virus found in this incoming message.
>> Checked by AVG - www.avg.com
>> Version: 8.5.392 / Virus Database: 270.13.32/2266 - Release Date: 07/27/09
>> 05:58:00
>>
>> _______________________________________________
>> General EVDL support: http://evdl.org/help/
>> Usage guidelines: http://evdl.org/help/index.html#conv
>> Archives: http://evdl.org/archive/
>> Subscription options: http://lists.sjsu.edu/mailman/listinfo/ev
>>
>>
>
>
> _______________________________________________
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>
>
> No virus found in this incoming message.
> Checked by AVG - www.avg.com
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> 06:00:00
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>
>


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Re: Experience?: equalization chargecausing standing voltage todroop

John O'Connor-3
As another point of reference, I may well be killing my interstate  
(us battery) workaholics, but for the past 3,000 miles I have been  
pulling 200 to 400 amps regularly on my 20 mile commute to work; and  
on the 3 mile hill leading to my house  I generally range between 300  
- 600 amps. This pulls me down to 1.7 volts per cell, but I am still  
only traveling about 35 mph or a road with posted limit of 50 mph. I  
pull over 2 times on average to let folk by. (did I mention I may be  
killing my batteries ;-)

I charge off a 20 amp 120v outlet at work and a 240v 50 amp outlet at  
home. Charger is a PFC-30 and I really find the variable input  
voltage helpful. (if only there were a knob on the voltage pot)

While at work I put in between 7 and 10 kWh over a period of about 6  
to 7 hours and usually 10 - 15 kWh at home probably in about the same  
time period.

I feel that at least my home charge is according to US Battery specs  
and I don't discharge much more that 60% discharge, but offset that  
good treatment by pulling too many amps and dropping the voltage  
lower than ideal.

I hope to get at least 2k more miles out of this pack, and anything  
more than that will be gravy given my treatment.  I don't know if  
that is realistic or not but thats what I'm preparing myself for.

Next pack will probably be lower amp hour rating therefore lower  
weight. Hopefully that will help me on my hill.

John

On Jul 29, 2009, at 7:42 PM, [hidden email] wrote:

> Chuck,
>
> I'm charging with a PFC20. The outlet is a 20 amp, 110V nominal  
> (122-124V actual), GFI protected circuit. Based on my Evision I'm  
> drawing 2.0 to 2.2 kW/hr.   That translates to 18 amps on the  
> outlet side.  On the battery side the current is 12-15A for the  
> constant current phase.
>
> For a 20 mile trip I use about 8kW. For the entire charge cycle  
> that takes about 6 hours to charge.
>
> I think you are on the conservative side for your max amp draw.  
> Given that your pack is at a relatively high SOC at the end of your  
> commute I would think 350A max is OK.  Lee Hart has a nice table in  
> the archives with max amp draws. for flooded lead acids you can go  
> a 400A in short bursts.
>
> Barry Oppenheim
> New Hope, PA
> www.JustAnotherEVConversion.blogspot.com
>
> -----Original Message-----
> From: Chuck Hursch <[hidden email]>
>
> Date: Wed, 29 Jul 2009 12:24:12
> To: Electric Vehicle Discussion List<[hidden email]>
> Subject: Re: [EVDL] Experience?: equalization charge
>  causing standing voltage todroop
>
>
> Barry,
>
> Thanks for recounting your experiences.
>
> I wanted to know how fast you charge your pack, what charger, and what
> AC source you have (120V or 240V).  I have a 15A limit on 120V  
> gear, so
> that means right now I'm bulk charging at 8.5-9A (kinda slow), and I'd
> like to move that up to 12A or thereabouts.  Zivan K2.  US Battery
> recommends C/10 bulk charging rate, so about 23A.
>
> Yeah, I'm trying to limit the battery current draw to 250A, and am
> largely successful in doing so.  I have had a number of battery  
> wizards
> tell me that 6V floodies like these will last longer with a ceiling of
> 250A.  It really crawls coming back up my steep hill at 250A, about
> 11-12mph.  I am usually coming back home fairly late in the  
> evening, so
> there is not much traffic. My rule is that coming up the hill, if  
> nobody
> is following me (and can't see any headlights coming up around the
> corner behind me), once I hit that grade and things settle in at 250A,
> that's where it is staying, follower or not (unless it was an  
> emergency
> vehicle, of course - the road is narrow with no pull-off, although I
> could probably saddle up to the side).  If somebody is following me,
> well, then it's put the peddle down pretty much all the way for  
> 350A and
> do 17-18mph.  Speed limit is 25mph, although even with my gas  
> vehicle I
> won't usually go that fast, since it's a narrow road with a curve and
> lots of bushes for deer to hide in.
>
> Well, for instance, yesterday my charge did not complete, since the
> timer shut down at 7AM at the end of the TOU off-peak period from the
> electrical utility.  I think the pack had hit its constant voltage
> stage, but wasn't there for long.  Voltages were higher on the trip  
> than
> if the pack had been sitting for a few hours at that constant voltage
> level - at least that's the way it seems.  I really don't understand
> that.  I think the surface structure of the plates must change somehow
> if they are held at a high voltage for very long - whether it's  
> damaging
> I'm trying to find out.
>
> Thanks,
> Chuck
>
> Barry Oppenheim wrote:
>> Chuck,
>>
>> So far the pack has been good to me (knock on wood, or lead in  
>> this case).
>> I use and charge it everyday.  I rarely take it below 50% SOC.  I  
>> also limit
>> the battery amp draw to 350A.
>>
>> My daily drive has a few steep hills that require 300-350A draws  
>> for 5-20
>> seconds.  In order to accomplish this with acceptable speed I have my
>> controller battery voltage limits set lower than most on the list  
>> recommend.
>> I'm using 1.5V/cell(108V) as a lower cutoff.  Most on the list  
>> (especially
>> the ones with experience and a lot smarter than me) would recommend
>> 1.75V/cell(126V) as the lower limit.
>>
>> I found that the higher cutoff voltage setting limited performance
>> (acceleration, hills) too much.  The lower limit seems to work  
>> better for
>> me.  And since the pack is mostly at a higher SOC and well  
>> balanced I think
>> the chances of reversing a cell are low.
>>
>> Even with the cutoff at 108V I've yet to see the voltage drop to  
>> anywhere
>> near that low.  With a 350A draw, end of the trip hill, the  
>> voltage at most
>> will drop to 115V-120V.  Only time will tell.
>>
>> Barry Oppenheim
>> New Hope, PA
>> www.JustAnotherEVConversion.blogspot.com
>>
>> -----Original Message-----
>> From: [hidden email] [mailto:[hidden email]]On
>> Behalf Of Chuck Hursch
>> Sent: Tuesday, July 28, 2009 5:45 PM
>> To: Electric Vehicle Discussion List
>> Subject: Re: [EVDL] Experience?: equalization charge causing standing
>> voltage todroop
>>
>>
>> Hi Barry,
>>
>> Your standing voltages are about where mine are at.  So at least  
>> I'm not
>> the only one with new-ish batteries in the high 6.30s.  I have  
>> about 7
>> months on mine, and about the same number of miles.  Are you  
>> liking your
>> battery pack - do they seem to hold up well under use?
>>
>> Chuck
>>
>> Barry Oppenheim wrote:
>>> Chuck,
>>>
>>> I also have the US2200XC's.  I've been charging using the US Battery
>>> recommended algorithm:  constant current till 7.75V/battery then  
>>> hold at
>>> constant voltage for 2-4 hours.  So for my 144V pack I will  
>>> charge to
>>> 185-186V and hold for two hours.  This results in ~10% more amp  
>>> hours
>> being
>>> put in then taken out (i.e. if I use 20amp hours I end up putting  
>>> 22 back
>>> in;  40 out, 44 in; etc).
>>>
>>> Eight hours after the charger stops the resting open voltage for  
>>> the pack
>> is
>>> 153V.  This translates to 6.375V/battery.
>>>
>>> The pack has been in service for ~5 months and ~1600 miles.  
>>> Except for an
>>> "accidental equalization" from a charger malfunction I have not  
>>> equalized
>>> the pack.  Based on daily half pack voltage readings and monthly
>> individual
>>> battery voltage readings the pack has stayed in balance.  I drive  
>>> the
>>> vehicle about 10-20 miles most days and charge each evening.
>>>
>>> I know that many knowledgable people on the list (Lee Hart and Rich
>> Rudman)
>>> recommend a lower max voltage http://www.evdl.org/pages/ 
>>> hartcharge.html.
>>> And the higher voltage I'm using is probably an equalization each  
>>> time I
>>> charge.  Despite this I'm continuing with the US Battery  
>>> algorithm for a
>> few
>>> reasons:
>>>
>>> 1.  In case a battery goes bad I don't want to void the warranty
>>> 2.  It seems to be keeping the batteries balanced
>>> 3.  The 10% overage back in seems about right based on a  
>>> conversation I
>> had
>>> with Rich Rudman
>>>
>>> Am I sacrificing battery life in order to keep a balanced pack?  
>>> Possibly.
>>> Maybe US Battery intentionally recommends a higher charge finishing
>> voltage
>>> at the expense of cycles in order to avoid having someone reverse  
>>> a cell.
>> I
>>> don't know.
>>>
>>> With only about 100 cycles on this pack I hopefully won't find  
>>> out for
>> years
>>> to come!  I'm a newbie at this so take everything I say and do  
>>> with a
>> large
>>> grain of salt :-)
>>>
>>> Barry Oppenheim
>>> New Hope, PA
>>> www.JustAnotherEVConversion.blogspot.com
>>>
>>>
>>>
>>>
>>> -----Original Message-----
>>> From: [hidden email] [mailto:[hidden email]]On
>>> Behalf Of Chuck Hursch
>>> Sent: Monday, July 27, 2009 5:25 PM
>>> To: Electric Vehicle Discussion List
>>> Subject: [EVDL] Experience?: equalization charge causing standing
>>> voltage todroop
>>>
>>>
>>> Has anybody else noticed that after doing an equalization charge,  
>>> that
>>> the standing voltage is lower?  I'm talking 6V floodies here.  My
>>> version of an equalization charge is 6A constant current, looking  
>>> for
>>> the pack's (or batteries) voltage roll-over (ie. the voltage goes up
>>> till it starts to go down).  My "algorithm" is to equalize charge  
>>> for a
>>> minimum of two hours, and longer if necessary, to see the voltage
>>> rollover.  I check the voltage every half hour.  In my case, almost
>>> everytime, I see the peak reading at 1/2 hour in (I think that  
>>> means the
>>> pack is pretty well topped off, but I do it for two hours to  
>>> allow any
>>> cells that are behind that I can't detect a chance to catch up).  
>>> The
>>> batteries will warm up about 8-10 degF through the process, and  
>>> the peak
>>> voltage reached on my 6-mo-old US2200XCs is ~131-132V on my 96V  
>>> pack,
>>> with each battery peaking in the range of 8.20-8.25V.  The pack  
>>> voltage
>>> will drop off about 0.5-1.0V from the peak by the end.  I'd like  
>>> to know
>>>   how people equalize their 6V floodie packs.
>>>
>>> The thing that gets me is that everytime I do this, my standing  
>>> voltage
>>> after several hours is lower than before, and takes a few days to
>>> recover.  What gets me even more is that the standing voltage for my
>>> new-ish 6V'ers is in the range 6.3-6.4V.  New-ish batteries I've  
>>> heard
>>> are usually in the range 6.4-6.5V.  My batteries' standing  
>>> voltage is
>>> more like those of mid-life batteries, but higher than the  
>>> traditional
>>> 100%-charge level given as 6.30V.
>>>
>>> And to add further to the aura of ?-marks on my gray matter, I  
>>> decided
>>> to try moving my constant-voltage setpoint from 118.4V (14.8V/
>>> 12V, I was
>>> actually closer to 119-120V, but temperature was lower than  
>>> 77degF) that
>>> I was at for many months (since some felt that the US Battery
>>> recommendation of 7.75V/batt or 2.58Vpc was too high)to this  
>>> 7.75V/6V
>>> battery.  So what happens?  My specific gravity readings move  
>>> up :-),
>>> about 10 points.  But, now when I walk out to the carport in the  
>>> morning
>>> to unplug, that CanPulse light (which is on over ~103V), which  
>>> usually
>>> was on after having the constant voltage at 118.4V, is now off
>>> everytime.  I think I'm happier at 7.75V.  But this seeming reverse
>>> relationship between standing voltage and hydrometer readings and  
>>> how
>>> hard the batteries are charged doesn't make sense, and I've been  
>>> having
>>> troubles with that for several years now - I've seen it across three
>> packs.
>>> I know Lee has said he doesn't put much stock in voltage  
>>> readings, but
>>> it's a might scary with my current standing voltage readings and the
>>> price of batteries.  I just had a cell go down over the last few  
>>> weeks,
>>> and it was sitting at 1235sg yesterday, while the rest were tight at
>>> 1260-1280 (I still have to make up my spreadsheet to get the actual
>>> numbers).  This pack has been quite good in that dept, till the  
>>> above
>>> cell started having problems.
>>>
>>> So please enlighten me.  What do others do for equalizing?  Should I
>>> drop the equalization charges, or do something different?  I used  
>>> to do
>>> them weakly, but now do 'em basically monthly, at least several  
>>> hours
>>> before my monthly hydrometer readings, and I've also started  
>>> doing it
>>> after I water my batteries at that monthly battery maintenance,  
>>> to stir
>>> the electrolyte.
>>>
>>> I drive about 12.5 miles a day on weekdays, charge overnight at  
>>> 8.5-9A
>>> DC.  A fair # of steep hills, with the main one being the hill to  
>>> get
>>> home, where I can usually keep it at 250 battery amps, unless a  
>>> car is
>>> following me.  I figure the more I can keep the lid at 250A max, the
>>> longer the batteries will last (it's slow coming up that hill,  
>>> though).
>>>
>>> Thanks,
>>> Chuck
>>>
>>>
>>>
>>> _______________________________________________
>>> General EVDL support: http://evdl.org/help/
>>> Usage guidelines: http://evdl.org/help/index.html#conv
>>> Archives: http://evdl.org/archive/
>>> Subscription options: http://lists.sjsu.edu/mailman/listinfo/ev
>>>
>>>
>>> No virus found in this incoming message.
>>> Checked by AVG - www.avg.com
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>>> 07/27/09
>>> 05:58:00
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>>> Usage guidelines: http://evdl.org/help/index.html#conv
>>> Archives: http://evdl.org/archive/
>>> Subscription options: http://lists.sjsu.edu/mailman/listinfo/ev
>>>
>>>
>>
>>
>> _______________________________________________
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>> Usage guidelines: http://evdl.org/help/index.html#conv
>> Archives: http://evdl.org/archive/
>> Subscription options: http://lists.sjsu.edu/mailman/listinfo/ev
>>
>>
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>> Checked by AVG - www.avg.com
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>> 07/28/09
>> 06:00:00
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>> _______________________________________________
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>> Usage guidelines: http://evdl.org/help/index.html#conv
>> Archives: http://evdl.org/archive/
>> Subscription options: http://lists.sjsu.edu/mailman/listinfo/ev
>>
>>
>
>
> _______________________________________________
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> Archives: http://evdl.org/archive/
> Subscription options: http://lists.sjsu.edu/mailman/listinfo/ev
>
>
>
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Re: Experience?: equalization chargecausing standing voltage todroop

Chuck Hursch-2
In reply to this post by Barry Oppenheim
Barry,

I had a look at your blog - nice!  I especially enjoyed the poodle that
seemed all legs.

On your May 16 blog entry - "Just rotten eggs", I learned the hard way
to add a timer to shut off the charger.  I had two thermal runaways in
my last pack.  I posted on that, threadname "Hot stinky batteries for
breakfast" or somesuch.

The hill back up to my apt. takes about 30-45 seconds.  The other steep
hill I go up sometimes, the south side of Wolfe Grade, is about a 325A
draw for a minute (although I haven't timed it) to keep up with traffic
at 30mph in second gear.  If coming back over that ridge, there is a
350-400A pull for a few seconds coming out of one corner.

Doing a blog looks like fun.  I've thought about posting about "where I
drive".  This being San Andreas Fault -affected country, there are lots
of parallel ridges and valleys.  So many of the towns are separated by
ridges.  To go to San Rafael, I have to go over a ridge, although I
could go around, but that would be a long ways.  To go to Mill Valley is
another ridge.

Chuck

[hidden email] wrote:

> Chuck,
>
> I'm charging with a PFC20. The outlet is a 20 amp, 110V nominal (122-124V actual), GFI protected circuit. Based on my Evision I'm drawing 2.0 to 2.2 kW/hr.   That translates to 18 amps on the outlet side.  On the battery side the current is 12-15A for the constant current phase.
>
> For a 20 mile trip I use about 8kW. For the entire charge cycle that takes about 6 hours to charge.
>
> I think you are on the conservative side for your max amp draw. Given that your pack is at a relatively high SOC at the end of your commute I would think 350A max is OK.  Lee Hart has a nice table in the archives with max amp draws. for flooded lead acids you can go a 400A in short bursts.
>
> Barry Oppenheim
> New Hope, PA
> www.JustAnotherEVConversion.blogspot.com
>
> -----Original Message-----
> From: Chuck Hursch <[hidden email]>
>
> Date: Wed, 29 Jul 2009 12:24:12
> To: Electric Vehicle Discussion List<[hidden email]>
> Subject: Re: [EVDL] Experience?: equalization charge
>  causing standing voltage todroop
>
>
> Barry,
>
[snip]

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Re: Experience?: equalization chargecausing standing voltage todroop

Phil Marino-2
In reply to this post by Barry Oppenheim
On Wed, Jul 29, 2009 at 7:42 PM, <[hidden email]> wrote:

> Chuck,
>
> I'm charging with a PFC20. The outlet is a 20 amp, 110V nominal (122-124V
> actual), GFI protected circuit. Based on my Evision I'm drawing 2.0 to 2.2
> kW/hr.


Barry - I think you mean 2.0 to 2.2 KW, right? That's the unit of power you
want here.



> That translates to 18 amps on the outlet side.  On the battery side the
> current is 12-15A for the constant current phase.
>
> For a 20 mile trip I use about 8kW.


And here, you must mean KW-hr or KWH.  That's energy.

Phil Marino


> For the entire charge cycle that takes about 6 hours to charge.
>
> I think you are on the conservative side for your max amp draw. Given that
> your pack is at a relatively high SOC at the end of your commute I would
> think 350A max is OK.  Lee Hart has a nice table in the archives with max
> amp draws. for flooded lead acids you can go a 400A in short bursts.
>
> Barry Oppenheim
> New Hope, PA
> www.JustAnotherEVConversion.blogspot.com
>
> -----Original Message-----
> From: Chuck Hursch <[hidden email]>
>
> Date: Wed, 29 Jul 2009 12:24:12
> To: Electric Vehicle Discussion List<[hidden email]>
> Subject: Re: [EVDL] Experience?: equalization charge
>  causing        standing        voltage todroop
>
>
> Barry,
>
> Thanks for recounting your experiences.
>
> I wanted to know how fast you charge your pack, what charger, and what
> AC source you have (120V or 240V).  I have a 15A limit on 120V gear, so
> that means right now I'm bulk charging at 8.5-9A (kinda slow), and I'd
> like to move that up to 12A or thereabouts.  Zivan K2.  US Battery
> recommends C/10 bulk charging rate, so about 23A.
>
> Yeah, I'm trying to limit the battery current draw to 250A, and am
> largely successful in doing so.  I have had a number of battery wizards
> tell me that 6V floodies like these will last longer with a ceiling of
> 250A.  It really crawls coming back up my steep hill at 250A, about
> 11-12mph.  I am usually coming back home fairly late in the evening, so
> there is not much traffic. My rule is that coming up the hill, if nobody
> is following me (and can't see any headlights coming up around the
> corner behind me), once I hit that grade and things settle in at 250A,
> that's where it is staying, follower or not (unless it was an emergency
> vehicle, of course - the road is narrow with no pull-off, although I
> could probably saddle up to the side).  If somebody is following me,
> well, then it's put the peddle down pretty much all the way for 350A and
> do 17-18mph.  Speed limit is 25mph, although even with my gas vehicle I
> won't usually go that fast, since it's a narrow road with a curve and
> lots of bushes for deer to hide in.
>
> Well, for instance, yesterday my charge did not complete, since the
> timer shut down at 7AM at the end of the TOU off-peak period from the
> electrical utility.  I think the pack had hit its constant voltage
> stage, but wasn't there for long.  Voltages were higher on the trip than
> if the pack had been sitting for a few hours at that constant voltage
> level - at least that's the way it seems.  I really don't understand
> that.  I think the surface structure of the plates must change somehow
> if they are held at a high voltage for very long - whether it's damaging
> I'm trying to find out.
>
> Thanks,
> Chuck
>
> Barry Oppenheim wrote:
> > Chuck,
> >
> > So far the pack has been good to me (knock on wood, or lead in this
> case).
> > I use and charge it everyday.  I rarely take it below 50% SOC.  I also
> limit
> > the battery amp draw to 350A.
> >
> > My daily drive has a few steep hills that require 300-350A draws for 5-20
> > seconds.  In order to accomplish this with acceptable speed I have my
> > controller battery voltage limits set lower than most on the list
> recommend.
> > I'm using 1.5V/cell(108V) as a lower cutoff.  Most on the list
> (especially
> > the ones with experience and a lot smarter than me) would recommend
> > 1.75V/cell(126V) as the lower limit.
> >
> > I found that the higher cutoff voltage setting limited performance
> > (acceleration, hills) too much.  The lower limit seems to work better for
> > me.  And since the pack is mostly at a higher SOC and well balanced I
> think
> > the chances of reversing a cell are low.
> >
> > Even with the cutoff at 108V I've yet to see the voltage drop to anywhere
> > near that low.  With a 350A draw, end of the trip hill, the voltage at
> most
> > will drop to 115V-120V.  Only time will tell.
> >
> > Barry Oppenheim
> > New Hope, PA
> > www.JustAnotherEVConversion.blogspot.com
> >
> > -----Original Message-----
> > From: [hidden email] [mailto:[hidden email]]On
> > Behalf Of Chuck Hursch
> > Sent: Tuesday, July 28, 2009 5:45 PM
> > To: Electric Vehicle Discussion List
> > Subject: Re: [EVDL] Experience?: equalization charge causing standing
> > voltage todroop
> >
> >
> > Hi Barry,
> >
> > Your standing voltages are about where mine are at.  So at least I'm not
> > the only one with new-ish batteries in the high 6.30s.  I have about 7
> > months on mine, and about the same number of miles.  Are you liking your
> > battery pack - do they seem to hold up well under use?
> >
> > Chuck
> >
> > Barry Oppenheim wrote:
> >> Chuck,
> >>
> >> I also have the US2200XC's.  I've been charging using the US Battery
> >> recommended algorithm:  constant current till 7.75V/battery then hold at
> >> constant voltage for 2-4 hours.  So for my 144V pack I will charge to
> >> 185-186V and hold for two hours.  This results in ~10% more amp hours
> > being
> >> put in then taken out (i.e. if I use 20amp hours I end up putting 22
> back
> >> in;  40 out, 44 in; etc).
> >>
> >> Eight hours after the charger stops the resting open voltage for the
> pack
> > is
> >> 153V.  This translates to 6.375V/battery.
> >>
> >> The pack has been in service for ~5 months and ~1600 miles.  Except for
> an
> >> "accidental equalization" from a charger malfunction I have not
> equalized
> >> the pack.  Based on daily half pack voltage readings and monthly
> > individual
> >> battery voltage readings the pack has stayed in balance.  I drive the
> >> vehicle about 10-20 miles most days and charge each evening.
> >>
> >> I know that many knowledgable people on the list (Lee Hart and Rich
> > Rudman)
> >> recommend a lower max voltage http://www.evdl.org/pages/hartcharge.html
> .
> >> And the higher voltage I'm using is probably an equalization each time I
> >> charge.  Despite this I'm continuing with the US Battery algorithm for a
> > few
> >> reasons:
> >>
> >> 1.  In case a battery goes bad I don't want to void the warranty
> >> 2.  It seems to be keeping the batteries balanced
> >> 3.  The 10% overage back in seems about right based on a conversation I
> > had
> >> with Rich Rudman
> >>
> >> Am I sacrificing battery life in order to keep a balanced pack?
>  Possibly.
> >> Maybe US Battery intentionally recommends a higher charge finishing
> > voltage
> >> at the expense of cycles in order to avoid having someone reverse a
> cell.
> > I
> >> don't know.
> >>
> >> With only about 100 cycles on this pack I hopefully won't find out for
> > years
> >> to come!  I'm a newbie at this so take everything I say and do with a
> > large
> >> grain of salt :-)
> >>
> >> Barry Oppenheim
> >> New Hope, PA
> >> www.JustAnotherEVConversion.blogspot.com
> >>
> >>
> >>
> >>
> >> -----Original Message-----
> >> From: [hidden email] [mailto:[hidden email]]On
> >> Behalf Of Chuck Hursch
> >> Sent: Monday, July 27, 2009 5:25 PM
> >> To: Electric Vehicle Discussion List
> >> Subject: [EVDL] Experience?: equalization charge causing standing
> >> voltage todroop
> >>
> >>
> >> Has anybody else noticed that after doing an equalization charge, that
> >> the standing voltage is lower?  I'm talking 6V floodies here.  My
> >> version of an equalization charge is 6A constant current, looking for
> >> the pack's (or batteries) voltage roll-over (ie. the voltage goes up
> >> till it starts to go down).  My "algorithm" is to equalize charge for a
> >> minimum of two hours, and longer if necessary, to see the voltage
> >> rollover.  I check the voltage every half hour.  In my case, almost
> >> everytime, I see the peak reading at 1/2 hour in (I think that means the
> >> pack is pretty well topped off, but I do it for two hours to allow any
> >> cells that are behind that I can't detect a chance to catch up).  The
> >> batteries will warm up about 8-10 degF through the process, and the peak
> >> voltage reached on my 6-mo-old US2200XCs is ~131-132V on my 96V pack,
> >> with each battery peaking in the range of 8.20-8.25V.  The pack voltage
> >> will drop off about 0.5-1.0V from the peak by the end.  I'd like to know
> >>   how people equalize their 6V floodie packs.
> >>
> >> The thing that gets me is that everytime I do this, my standing voltage
> >> after several hours is lower than before, and takes a few days to
> >> recover.  What gets me even more is that the standing voltage for my
> >> new-ish 6V'ers is in the range 6.3-6.4V.  New-ish batteries I've heard
> >> are usually in the range 6.4-6.5V.  My batteries' standing voltage is
> >> more like those of mid-life batteries, but higher than the traditional
> >> 100%-charge level given as 6.30V.
> >>
> >> And to add further to the aura of ?-marks on my gray matter, I decided
> >> to try moving my constant-voltage setpoint from 118.4V (14.8V/12V, I was
> >> actually closer to 119-120V, but temperature was lower than 77degF) that
> >> I was at for many months (since some felt that the US Battery
> >> recommendation of 7.75V/batt or 2.58Vpc was too high)to this 7.75V/6V
> >> battery.  So what happens?  My specific gravity readings move up :-),
> >> about 10 points.  But, now when I walk out to the carport in the morning
> >> to unplug, that CanPulse light (which is on over ~103V), which usually
> >> was on after having the constant voltage at 118.4V, is now off
> >> everytime.  I think I'm happier at 7.75V.  But this seeming reverse
> >> relationship between standing voltage and hydrometer readings and how
> >> hard the batteries are charged doesn't make sense, and I've been having
> >> troubles with that for several years now - I've seen it across three
> > packs.
> >> I know Lee has said he doesn't put much stock in voltage readings, but
> >> it's a might scary with my current standing voltage readings and the
> >> price of batteries.  I just had a cell go down over the last few weeks,
> >> and it was sitting at 1235sg yesterday, while the rest were tight at
> >> 1260-1280 (I still have to make up my spreadsheet to get the actual
> >> numbers).  This pack has been quite good in that dept, till the above
> >> cell started having problems.
> >>
> >> So please enlighten me.  What do others do for equalizing?  Should I
> >> drop the equalization charges, or do something different?  I used to do
> >> them weakly, but now do 'em basically monthly, at least several hours
> >> before my monthly hydrometer readings, and I've also started doing it
> >> after I water my batteries at that monthly battery maintenance, to stir
> >> the electrolyte.
> >>
> >> I drive about 12.5 miles a day on weekdays, charge overnight at 8.5-9A
> >> DC.  A fair # of steep hills, with the main one being the hill to get
> >> home, where I can usually keep it at 250 battery amps, unless a car is
> >> following me.  I figure the more I can keep the lid at 250A max, the
> >> longer the batteries will last (it's slow coming up that hill, though).
> >>
> >> Thanks,
> >> Chuck
> >>
> >>
> >>
> >> _______________________________________________
> >> General EVDL support: http://evdl.org/help/
> >> Usage guidelines: http://evdl.org/help/index.html#conv
> >> Archives: http://evdl.org/archive/
> >> Subscription options: http://lists.sjsu.edu/mailman/listinfo/ev
> >>
> >>
> >> No virus found in this incoming message.
> >> Checked by AVG - www.avg.com
> >> Version: 8.5.392 / Virus Database: 270.13.32/2266 - Release Date:
> 07/27/09
> >> 05:58:00
> >>
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Re: Experience?: equalization chargecausing standing voltagetodroop

Cor van de Water
In reply to this post by John O'Connor-3
Hi John,

Did you try driving in the next lower gear
(higher RPMs, lower Amps)?
It may be that you are already in the optimal gear
for your hill, but 600A sounds like a pretty hefty current
so I wonder if you are lugging your motor or just need a
lot of power to push a lot of weight uphill.

Be careful with a lighter pack, it does make the car
lighter so it requires less amps to be pushed uphill
but it can also sustain less amps due to the smaller
cells (dependent on the type of batteries)....

Success,

Cor van de Water
Director HW & Systems Architecture Group
Proxim Wireless Corporation http://www.proxim.com
Email: [hidden email]    Private: http://www.cvandewater.com
Skype: cor_van_de_water     IM: [hidden email]
Tel: +1 408 383 7626        magicJack: +1 408 844 3932
Tel: +91 (040)23117400 x203 XoIP: +31877841130

Please consider the environment before printing this e-mail.
-----Original Message-----
From: [hidden email] [mailto:[hidden email]] On
Behalf Of John O'Connor
Sent: Thursday, July 30, 2009 6:26 AM
To: Electric Vehicle Discussion List
Subject: Re: [EVDL] Experience?: equalization chargecausing standing
voltagetodroop

As another point of reference, I may well be killing my interstate  
(us battery) workaholics, but for the past 3,000 miles I have been  
pulling 200 to 400 amps regularly on my 20 mile commute to work; and  
on the 3 mile hill leading to my house  I generally range between 300  
- 600 amps. This pulls me down to 1.7 volts per cell, but I am still  
only traveling about 35 mph or a road with posted limit of 50 mph. I  
pull over 2 times on average to let folk by. (did I mention I may be  
killing my batteries ;-)

I charge off a 20 amp 120v outlet at work and a 240v 50 amp outlet at  
home. Charger is a PFC-30 and I really find the variable input  
voltage helpful. (if only there were a knob on the voltage pot)

While at work I put in between 7 and 10 kWh over a period of about 6  
to 7 hours and usually 10 - 15 kWh at home probably in about the same  
time period.

I feel that at least my home charge is according to US Battery specs  
and I don't discharge much more that 60% discharge, but offset that  
good treatment by pulling too many amps and dropping the voltage  
lower than ideal.

I hope to get at least 2k more miles out of this pack, and anything  
more than that will be gravy given my treatment.  I don't know if  
that is realistic or not but thats what I'm preparing myself for.

Next pack will probably be lower amp hour rating therefore lower  
weight. Hopefully that will help me on my hill.

John

On Jul 29, 2009, at 7:42 PM, [hidden email] wrote:

> Chuck,
>
> I'm charging with a PFC20. The outlet is a 20 amp, 110V nominal  
> (122-124V actual), GFI protected circuit. Based on my Evision I'm  
> drawing 2.0 to 2.2 kW/hr.   That translates to 18 amps on the  
> outlet side.  On the battery side the current is 12-15A for the  
> constant current phase.
>
> For a 20 mile trip I use about 8kW. For the entire charge cycle  
> that takes about 6 hours to charge.
>
> I think you are on the conservative side for your max amp draw.  
> Given that your pack is at a relatively high SOC at the end of your  
> commute I would think 350A max is OK.  Lee Hart has a nice table in  
> the archives with max amp draws. for flooded lead acids you can go  
> a 400A in short bursts.
>
> Barry Oppenheim
> New Hope, PA
> www.JustAnotherEVConversion.blogspot.com
>
> -----Original Message-----
> From: Chuck Hursch <[hidden email]>
>
> Date: Wed, 29 Jul 2009 12:24:12
> To: Electric Vehicle Discussion List<[hidden email]>
> Subject: Re: [EVDL] Experience?: equalization charge
>  causing standing voltage todroop
>
>
> Barry,
>
> Thanks for recounting your experiences.
>
> I wanted to know how fast you charge your pack, what charger, and what
> AC source you have (120V or 240V).  I have a 15A limit on 120V  
> gear, so
> that means right now I'm bulk charging at 8.5-9A (kinda slow), and I'd
> like to move that up to 12A or thereabouts.  Zivan K2.  US Battery
> recommends C/10 bulk charging rate, so about 23A.
>
> Yeah, I'm trying to limit the battery current draw to 250A, and am
> largely successful in doing so.  I have had a number of battery  
> wizards
> tell me that 6V floodies like these will last longer with a ceiling of
> 250A.  It really crawls coming back up my steep hill at 250A, about
> 11-12mph.  I am usually coming back home fairly late in the  
> evening, so
> there is not much traffic. My rule is that coming up the hill, if  
> nobody
> is following me (and can't see any headlights coming up around the
> corner behind me), once I hit that grade and things settle in at 250A,
> that's where it is staying, follower or not (unless it was an  
> emergency
> vehicle, of course - the road is narrow with no pull-off, although I
> could probably saddle up to the side).  If somebody is following me,
> well, then it's put the peddle down pretty much all the way for  
> 350A and
> do 17-18mph.  Speed limit is 25mph, although even with my gas  
> vehicle I
> won't usually go that fast, since it's a narrow road with a curve and
> lots of bushes for deer to hide in.
>
> Well, for instance, yesterday my charge did not complete, since the
> timer shut down at 7AM at the end of the TOU off-peak period from the
> electrical utility.  I think the pack had hit its constant voltage
> stage, but wasn't there for long.  Voltages were higher on the trip  
> than
> if the pack had been sitting for a few hours at that constant voltage
> level - at least that's the way it seems.  I really don't understand
> that.  I think the surface structure of the plates must change somehow
> if they are held at a high voltage for very long - whether it's  
> damaging
> I'm trying to find out.
>
> Thanks,
> Chuck
>
> Barry Oppenheim wrote:
>> Chuck,
>>
>> So far the pack has been good to me (knock on wood, or lead in  
>> this case).
>> I use and charge it everyday.  I rarely take it below 50% SOC.  I  
>> also limit
>> the battery amp draw to 350A.
>>
>> My daily drive has a few steep hills that require 300-350A draws  
>> for 5-20
>> seconds.  In order to accomplish this with acceptable speed I have my
>> controller battery voltage limits set lower than most on the list  
>> recommend.
>> I'm using 1.5V/cell(108V) as a lower cutoff.  Most on the list  
>> (especially
>> the ones with experience and a lot smarter than me) would recommend
>> 1.75V/cell(126V) as the lower limit.
>>
>> I found that the higher cutoff voltage setting limited performance
>> (acceleration, hills) too much.  The lower limit seems to work  
>> better for
>> me.  And since the pack is mostly at a higher SOC and well  
>> balanced I think
>> the chances of reversing a cell are low.
>>
>> Even with the cutoff at 108V I've yet to see the voltage drop to  
>> anywhere
>> near that low.  With a 350A draw, end of the trip hill, the  
>> voltage at most
>> will drop to 115V-120V.  Only time will tell.
>>
>> Barry Oppenheim
>> New Hope, PA
>> www.JustAnotherEVConversion.blogspot.com
>>
>> -----Original Message-----
>> From: [hidden email] [mailto:[hidden email]]On
>> Behalf Of Chuck Hursch
>> Sent: Tuesday, July 28, 2009 5:45 PM
>> To: Electric Vehicle Discussion List
>> Subject: Re: [EVDL] Experience?: equalization charge causing standing
>> voltage todroop
>>
>>
>> Hi Barry,
>>
>> Your standing voltages are about where mine are at.  So at least  
>> I'm not
>> the only one with new-ish batteries in the high 6.30s.  I have  
>> about 7
>> months on mine, and about the same number of miles.  Are you  
>> liking your
>> battery pack - do they seem to hold up well under use?
>>
>> Chuck
>>
>> Barry Oppenheim wrote:
>>> Chuck,
>>>
>>> I also have the US2200XC's.  I've been charging using the US Battery
>>> recommended algorithm:  constant current till 7.75V/battery then  
>>> hold at
>>> constant voltage for 2-4 hours.  So for my 144V pack I will  
>>> charge to
>>> 185-186V and hold for two hours.  This results in ~10% more amp  
>>> hours
>> being
>>> put in then taken out (i.e. if I use 20amp hours I end up putting  
>>> 22 back
>>> in;  40 out, 44 in; etc).
>>>
>>> Eight hours after the charger stops the resting open voltage for  
>>> the pack
>> is
>>> 153V.  This translates to 6.375V/battery.
>>>
>>> The pack has been in service for ~5 months and ~1600 miles.  
>>> Except for an
>>> "accidental equalization" from a charger malfunction I have not  
>>> equalized
>>> the pack.  Based on daily half pack voltage readings and monthly
>> individual
>>> battery voltage readings the pack has stayed in balance.  I drive  
>>> the
>>> vehicle about 10-20 miles most days and charge each evening.
>>>
>>> I know that many knowledgable people on the list (Lee Hart and Rich
>> Rudman)
>>> recommend a lower max voltage http://www.evdl.org/pages/ 
>>> hartcharge.html.
>>> And the higher voltage I'm using is probably an equalization each  
>>> time I
>>> charge.  Despite this I'm continuing with the US Battery  
>>> algorithm for a
>> few
>>> reasons:
>>>
>>> 1.  In case a battery goes bad I don't want to void the warranty
>>> 2.  It seems to be keeping the batteries balanced
>>> 3.  The 10% overage back in seems about right based on a  
>>> conversation I
>> had
>>> with Rich Rudman
>>>
>>> Am I sacrificing battery life in order to keep a balanced pack?  
>>> Possibly.
>>> Maybe US Battery intentionally recommends a higher charge finishing
>> voltage
>>> at the expense of cycles in order to avoid having someone reverse  
>>> a cell.
>> I
>>> don't know.
>>>
>>> With only about 100 cycles on this pack I hopefully won't find  
>>> out for
>> years
>>> to come!  I'm a newbie at this so take everything I say and do  
>>> with a
>> large
>>> grain of salt :-)
>>>
>>> Barry Oppenheim
>>> New Hope, PA
>>> www.JustAnotherEVConversion.blogspot.com
>>>
>>>
>>>
>>>
>>> -----Original Message-----
>>> From: [hidden email] [mailto:[hidden email]]On
>>> Behalf Of Chuck Hursch
>>> Sent: Monday, July 27, 2009 5:25 PM
>>> To: Electric Vehicle Discussion List
>>> Subject: [EVDL] Experience?: equalization charge causing standing
>>> voltage todroop
>>>
>>>
>>> Has anybody else noticed that after doing an equalization charge,  
>>> that
>>> the standing voltage is lower?  I'm talking 6V floodies here.  My
>>> version of an equalization charge is 6A constant current, looking  
>>> for
>>> the pack's (or batteries) voltage roll-over (ie. the voltage goes up
>>> till it starts to go down).  My "algorithm" is to equalize charge  
>>> for a
>>> minimum of two hours, and longer if necessary, to see the voltage
>>> rollover.  I check the voltage every half hour.  In my case, almost
>>> everytime, I see the peak reading at 1/2 hour in (I think that  
>>> means the
>>> pack is pretty well topped off, but I do it for two hours to  
>>> allow any
>>> cells that are behind that I can't detect a chance to catch up).  
>>> The
>>> batteries will warm up about 8-10 degF through the process, and  
>>> the peak
>>> voltage reached on my 6-mo-old US2200XCs is ~131-132V on my 96V  
>>> pack,
>>> with each battery peaking in the range of 8.20-8.25V.  The pack  
>>> voltage
>>> will drop off about 0.5-1.0V from the peak by the end.  I'd like  
>>> to know
>>>   how people equalize their 6V floodie packs.
>>>
>>> The thing that gets me is that everytime I do this, my standing  
>>> voltage
>>> after several hours is lower than before, and takes a few days to
>>> recover.  What gets me even more is that the standing voltage for my
>>> new-ish 6V'ers is in the range 6.3-6.4V.  New-ish batteries I've  
>>> heard
>>> are usually in the range 6.4-6.5V.  My batteries' standing  
>>> voltage is
>>> more like those of mid-life batteries, but higher than the  
>>> traditional
>>> 100%-charge level given as 6.30V.
>>>
>>> And to add further to the aura of ?-marks on my gray matter, I  
>>> decided
>>> to try moving my constant-voltage setpoint from 118.4V (14.8V/
>>> 12V, I was
>>> actually closer to 119-120V, but temperature was lower than  
>>> 77degF) that
>>> I was at for many months (since some felt that the US Battery
>>> recommendation of 7.75V/batt or 2.58Vpc was too high)to this  
>>> 7.75V/6V
>>> battery.  So what happens?  My specific gravity readings move  
>>> up :-),
>>> about 10 points.  But, now when I walk out to the carport in the  
>>> morning
>>> to unplug, that CanPulse light (which is on over ~103V), which  
>>> usually
>>> was on after having the constant voltage at 118.4V, is now off
>>> everytime.  I think I'm happier at 7.75V.  But this seeming reverse
>>> relationship between standing voltage and hydrometer readings and  
>>> how
>>> hard the batteries are charged doesn't make sense, and I've been  
>>> having
>>> troubles with that for several years now - I've seen it across three
>> packs.
>>> I know Lee has said he doesn't put much stock in voltage  
>>> readings, but
>>> it's a might scary with my current standing voltage readings and the
>>> price of batteries.  I just had a cell go down over the last few  
>>> weeks,
>>> and it was sitting at 1235sg yesterday, while the rest were tight at
>>> 1260-1280 (I still have to make up my spreadsheet to get the actual
>>> numbers).  This pack has been quite good in that dept, till the  
>>> above
>>> cell started having problems.
>>>
>>> So please enlighten me.  What do others do for equalizing?  Should I
>>> drop the equalization charges, or do something different?  I used  
>>> to do
>>> them weakly, but now do 'em basically monthly, at least several  
>>> hours
>>> before my monthly hydrometer readings, and I've also started  
>>> doing it
>>> after I water my batteries at that monthly battery maintenance,  
>>> to stir
>>> the electrolyte.
>>>
>>> I drive about 12.5 miles a day on weekdays, charge overnight at  
>>> 8.5-9A
>>> DC.  A fair # of steep hills, with the main one being the hill to  
>>> get
>>> home, where I can usually keep it at 250 battery amps, unless a  
>>> car is
>>> following me.  I figure the more I can keep the lid at 250A max, the
>>> longer the batteries will last (it's slow coming up that hill,  
>>> though).
>>>
>>> Thanks,
>>> Chuck
>>>
>>>
>>>
>>> _______________________________________________
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>>> 05:58:00
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>>>
>>
>>
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>>
>
>
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>
>
>
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Re: Experience?: equalization chargecausing standing voltagetodroop

John O'Connor-3
Hi Cor,

I don't think I am lugging motor, I am in 2nd gear at this point. I  
will sometimes drop down into 1st the only effect is generally that I  
slow down. I basically need a lot of power to get up the hill.

If I go with the lighter pack it will be the same interstate brand,  
just lower amp-hour capacity which drops lbs.


John


On Aug 1, 2009, at 7:19 PM, Cor van de Water wrote:

> Hi John,
>
> Did you try driving in the next lower gear
> (higher RPMs, lower Amps)?
> It may be that you are already in the optimal gear
> for your hill, but 600A sounds like a pretty hefty current
> so I wonder if you are lugging your motor or just need a
> lot of power to push a lot of weight uphill.
>
> Be careful with a lighter pack, it does make the car
> lighter so it requires less amps to be pushed uphill
> but it can also sustain less amps due to the smaller
> cells (dependent on the type of batteries)....
>
> Success,
>
> Cor van de Water
> Director HW & Systems Architecture Group
> Proxim Wireless Corporation http://www.proxim.com
> Email: [hidden email]    Private: http://www.cvandewater.com
> Skype: cor_van_de_water     IM: [hidden email]
> Tel: +1 408 383 7626        magicJack: +1 408 844 3932
> Tel: +91 (040)23117400 x203 XoIP: +31877841130
>
> Please consider the environment before printing this e-mail.
> -----Original Message-----
> From: [hidden email] [mailto:[hidden email]] On
> Behalf Of John O'Connor
> Sent: Thursday, July 30, 2009 6:26 AM
> To: Electric Vehicle Discussion List
> Subject: Re: [EVDL] Experience?: equalization chargecausing standing
> voltagetodroop
>
> As another point of reference, I may well be killing my interstate
> (us battery) workaholics, but for the past 3,000 miles I have been
> pulling 200 to 400 amps regularly on my 20 mile commute to work; and
> on the 3 mile hill leading to my house  I generally range between 300
> - 600 amps. This pulls me down to 1.7 volts per cell, but I am still
> only traveling about 35 mph or a road with posted limit of 50 mph. I
> pull over 2 times on average to let folk by. (did I mention I may be
> killing my batteries ;-)
>
> I charge off a 20 amp 120v outlet at work and a 240v 50 amp outlet at
> home. Charger is a PFC-30 and I really find the variable input
> voltage helpful. (if only there were a knob on the voltage pot)
>
> While at work I put in between 7 and 10 kWh over a period of about 6
> to 7 hours and usually 10 - 15 kWh at home probably in about the same
> time period.
>
> I feel that at least my home charge is according to US Battery specs
> and I don't discharge much more that 60% discharge, but offset that
> good treatment by pulling too many amps and dropping the voltage
> lower than ideal.
>
> I hope to get at least 2k more miles out of this pack, and anything
> more than that will be gravy given my treatment.  I don't know if
> that is realistic or not but thats what I'm preparing myself for.
>
> Next pack will probably be lower amp hour rating therefore lower
> weight. Hopefully that will help me on my hill.
>
> John
>
> On Jul 29, 2009, at 7:42 PM, [hidden email] wrote:
>
>> Chuck,
>>
>> I'm charging with a PFC20. The outlet is a 20 amp, 110V nominal
>> (122-124V actual), GFI protected circuit. Based on my Evision I'm
>> drawing 2.0 to 2.2 kW/hr.   That translates to 18 amps on the
>> outlet side.  On the battery side the current is 12-15A for the
>> constant current phase.
>>
>> For a 20 mile trip I use about 8kW. For the entire charge cycle
>> that takes about 6 hours to charge.
>>
>> I think you are on the conservative side for your max amp draw.
>> Given that your pack is at a relatively high SOC at the end of your
>> commute I would think 350A max is OK.  Lee Hart has a nice table in
>> the archives with max amp draws. for flooded lead acids you can go
>> a 400A in short bursts.
>>
>> Barry Oppenheim
>> New Hope, PA
>> www.JustAnotherEVConversion.blogspot.com
>>
>> -----Original Message-----
>> From: Chuck Hursch <[hidden email]>
>>
>> Date: Wed, 29 Jul 2009 12:24:12
>> To: Electric Vehicle Discussion List<[hidden email]>
>> Subject: Re: [EVDL] Experience?: equalization charge
>>  causing standing voltage todroop
>>
>>
>> Barry,
>>
>> Thanks for recounting your experiences.
>>
>> I wanted to know how fast you charge your pack, what charger, and  
>> what
>> AC source you have (120V or 240V).  I have a 15A limit on 120V
>> gear, so
>> that means right now I'm bulk charging at 8.5-9A (kinda slow), and  
>> I'd
>> like to move that up to 12A or thereabouts.  Zivan K2.  US Battery
>> recommends C/10 bulk charging rate, so about 23A.
>>
>> Yeah, I'm trying to limit the battery current draw to 250A, and am
>> largely successful in doing so.  I have had a number of battery
>> wizards
>> tell me that 6V floodies like these will last longer with a  
>> ceiling of
>> 250A.  It really crawls coming back up my steep hill at 250A, about
>> 11-12mph.  I am usually coming back home fairly late in the
>> evening, so
>> there is not much traffic. My rule is that coming up the hill, if
>> nobody
>> is following me (and can't see any headlights coming up around the
>> corner behind me), once I hit that grade and things settle in at  
>> 250A,
>> that's where it is staying, follower or not (unless it was an
>> emergency
>> vehicle, of course - the road is narrow with no pull-off, although I
>> could probably saddle up to the side).  If somebody is following me,
>> well, then it's put the peddle down pretty much all the way for
>> 350A and
>> do 17-18mph.  Speed limit is 25mph, although even with my gas
>> vehicle I
>> won't usually go that fast, since it's a narrow road with a curve and
>> lots of bushes for deer to hide in.
>>
>> Well, for instance, yesterday my charge did not complete, since the
>> timer shut down at 7AM at the end of the TOU off-peak period from the
>> electrical utility.  I think the pack had hit its constant voltage
>> stage, but wasn't there for long.  Voltages were higher on the trip
>> than
>> if the pack had been sitting for a few hours at that constant voltage
>> level - at least that's the way it seems.  I really don't understand
>> that.  I think the surface structure of the plates must change  
>> somehow
>> if they are held at a high voltage for very long - whether it's
>> damaging
>> I'm trying to find out.
>>
>> Thanks,
>> Chuck
>>
>> Barry Oppenheim wrote:
>>> Chuck,
>>>
>>> So far the pack has been good to me (knock on wood, or lead in
>>> this case).
>>> I use and charge it everyday.  I rarely take it below 50% SOC.  I
>>> also limit
>>> the battery amp draw to 350A.
>>>
>>> My daily drive has a few steep hills that require 300-350A draws
>>> for 5-20
>>> seconds.  In order to accomplish this with acceptable speed I  
>>> have my
>>> controller battery voltage limits set lower than most on the list
>>> recommend.
>>> I'm using 1.5V/cell(108V) as a lower cutoff.  Most on the list
>>> (especially
>>> the ones with experience and a lot smarter than me) would recommend
>>> 1.75V/cell(126V) as the lower limit.
>>>
>>> I found that the higher cutoff voltage setting limited performance
>>> (acceleration, hills) too much.  The lower limit seems to work
>>> better for
>>> me.  And since the pack is mostly at a higher SOC and well
>>> balanced I think
>>> the chances of reversing a cell are low.
>>>
>>> Even with the cutoff at 108V I've yet to see the voltage drop to
>>> anywhere
>>> near that low.  With a 350A draw, end of the trip hill, the
>>> voltage at most
>>> will drop to 115V-120V.  Only time will tell.
>>>
>>> Barry Oppenheim
>>> New Hope, PA
>>> www.JustAnotherEVConversion.blogspot.com
>>>
>>> -----Original Message-----
>>> From: [hidden email] [mailto:[hidden email]]On
>>> Behalf Of Chuck Hursch
>>> Sent: Tuesday, July 28, 2009 5:45 PM
>>> To: Electric Vehicle Discussion List
>>> Subject: Re: [EVDL] Experience?: equalization charge causing  
>>> standing
>>> voltage todroop
>>>
>>>
>>> Hi Barry,
>>>
>>> Your standing voltages are about where mine are at.  So at least
>>> I'm not
>>> the only one with new-ish batteries in the high 6.30s.  I have
>>> about 7
>>> months on mine, and about the same number of miles.  Are you
>>> liking your
>>> battery pack - do they seem to hold up well under use?
>>>
>>> Chuck
>>>
>>> Barry Oppenheim wrote:
>>>> Chuck,
>>>>
>>>> I also have the US2200XC's.  I've been charging using the US  
>>>> Battery
>>>> recommended algorithm:  constant current till 7.75V/battery then
>>>> hold at
>>>> constant voltage for 2-4 hours.  So for my 144V pack I will
>>>> charge to
>>>> 185-186V and hold for two hours.  This results in ~10% more amp
>>>> hours
>>> being
>>>> put in then taken out (i.e. if I use 20amp hours I end up putting
>>>> 22 back
>>>> in;  40 out, 44 in; etc).
>>>>
>>>> Eight hours after the charger stops the resting open voltage for
>>>> the pack
>>> is
>>>> 153V.  This translates to 6.375V/battery.
>>>>
>>>> The pack has been in service for ~5 months and ~1600 miles.
>>>> Except for an
>>>> "accidental equalization" from a charger malfunction I have not
>>>> equalized
>>>> the pack.  Based on daily half pack voltage readings and monthly
>>> individual
>>>> battery voltage readings the pack has stayed in balance.  I drive
>>>> the
>>>> vehicle about 10-20 miles most days and charge each evening.
>>>>
>>>> I know that many knowledgable people on the list (Lee Hart and Rich
>>> Rudman)
>>>> recommend a lower max voltage http://www.evdl.org/pages/
>>>> hartcharge.html.
>>>> And the higher voltage I'm using is probably an equalization each
>>>> time I
>>>> charge.  Despite this I'm continuing with the US Battery
>>>> algorithm for a
>>> few
>>>> reasons:
>>>>
>>>> 1.  In case a battery goes bad I don't want to void the warranty
>>>> 2.  It seems to be keeping the batteries balanced
>>>> 3.  The 10% overage back in seems about right based on a
>>>> conversation I
>>> had
>>>> with Rich Rudman
>>>>
>>>> Am I sacrificing battery life in order to keep a balanced pack?
>>>> Possibly.
>>>> Maybe US Battery intentionally recommends a higher charge finishing
>>> voltage
>>>> at the expense of cycles in order to avoid having someone reverse
>>>> a cell.
>>> I
>>>> don't know.
>>>>
>>>> With only about 100 cycles on this pack I hopefully won't find
>>>> out for
>>> years
>>>> to come!  I'm a newbie at this so take everything I say and do
>>>> with a
>>> large
>>>> grain of salt :-)
>>>>
>>>> Barry Oppenheim
>>>> New Hope, PA
>>>> www.JustAnotherEVConversion.blogspot.com
>>>>
>>>>
>>>>
>>>>
>>>> -----Original Message-----
>>>> From: [hidden email] [mailto:ev-
>>>> [hidden email]]On
>>>> Behalf Of Chuck Hursch
>>>> Sent: Monday, July 27, 2009 5:25 PM
>>>> To: Electric Vehicle Discussion List
>>>> Subject: [EVDL] Experience?: equalization charge causing standing
>>>> voltage todroop
>>>>
>>>>
>>>> Has anybody else noticed that after doing an equalization charge,
>>>> that
>>>> the standing voltage is lower?  I'm talking 6V floodies here.  My
>>>> version of an equalization charge is 6A constant current, looking
>>>> for
>>>> the pack's (or batteries) voltage roll-over (ie. the voltage  
>>>> goes up
>>>> till it starts to go down).  My "algorithm" is to equalize charge
>>>> for a
>>>> minimum of two hours, and longer if necessary, to see the voltage
>>>> rollover.  I check the voltage every half hour.  In my case, almost
>>>> everytime, I see the peak reading at 1/2 hour in (I think that
>>>> means the
>>>> pack is pretty well topped off, but I do it for two hours to
>>>> allow any
>>>> cells that are behind that I can't detect a chance to catch up).
>>>> The
>>>> batteries will warm up about 8-10 degF through the process, and
>>>> the peak
>>>> voltage reached on my 6-mo-old US2200XCs is ~131-132V on my 96V
>>>> pack,
>>>> with each battery peaking in the range of 8.20-8.25V.  The pack
>>>> voltage
>>>> will drop off about 0.5-1.0V from the peak by the end.  I'd like
>>>> to know
>>>>   how people equalize their 6V floodie packs.
>>>>
>>>> The thing that gets me is that everytime I do this, my standing
>>>> voltage
>>>> after several hours is lower than before, and takes a few days to
>>>> recover.  What gets me even more is that the standing voltage  
>>>> for my
>>>> new-ish 6V'ers is in the range 6.3-6.4V.  New-ish batteries I've
>>>> heard
>>>> are usually in the range 6.4-6.5V.  My batteries' standing
>>>> voltage is
>>>> more like those of mid-life batteries, but higher than the
>>>> traditional
>>>> 100%-charge level given as 6.30V.
>>>>
>>>> And to add further to the aura of ?-marks on my gray matter, I
>>>> decided
>>>> to try moving my constant-voltage setpoint from 118.4V (14.8V/
>>>> 12V, I was
>>>> actually closer to 119-120V, but temperature was lower than
>>>> 77degF) that
>>>> I was at for many months (since some felt that the US Battery
>>>> recommendation of 7.75V/batt or 2.58Vpc was too high)to this
>>>> 7.75V/6V
>>>> battery.  So what happens?  My specific gravity readings move
>>>> up :-),
>>>> about 10 points.  But, now when I walk out to the carport in the
>>>> morning
>>>> to unplug, that CanPulse light (which is on over ~103V), which
>>>> usually
>>>> was on after having the constant voltage at 118.4V, is now off
>>>> everytime.  I think I'm happier at 7.75V.  But this seeming reverse
>>>> relationship between standing voltage and hydrometer readings and
>>>> how
>>>> hard the batteries are charged doesn't make sense, and I've been
>>>> having
>>>> troubles with that for several years now - I've seen it across  
>>>> three
>>> packs.
>>>> I know Lee has said he doesn't put much stock in voltage
>>>> readings, but
>>>> it's a might scary with my current standing voltage readings and  
>>>> the
>>>> price of batteries.  I just had a cell go down over the last few
>>>> weeks,
>>>> and it was sitting at 1235sg yesterday, while the rest were  
>>>> tight at
>>>> 1260-1280 (I still have to make up my spreadsheet to get the actual
>>>> numbers).  This pack has been quite good in that dept, till the
>>>> above
>>>> cell started having problems.
>>>>
>>>> So please enlighten me.  What do others do for equalizing?  
>>>> Should I
>>>> drop the equalization charges, or do something different?  I used
>>>> to do
>>>> them weakly, but now do 'em basically monthly, at least several
>>>> hours
>>>> before my monthly hydrometer readings, and I've also started
>>>> doing it
>>>> after I water my batteries at that monthly battery maintenance,
>>>> to stir
>>>> the electrolyte.
>>>>
>>>> I drive about 12.5 miles a day on weekdays, charge overnight at
>>>> 8.5-9A
>>>> DC.  A fair # of steep hills, with the main one being the hill to
>>>> get
>>>> home, where I can usually keep it at 250 battery amps, unless a
>>>> car is
>>>> following me.  I figure the more I can keep the lid at 250A max,  
>>>> the
>>>> longer the batteries will last (it's slow coming up that hill,
>>>> though).
>>>>
>>>> Thanks,
>>>> Chuck
>>>>
>>>>
>>>>
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>>>>
>>>
>>>
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>>>
>>
>>
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Re: Experience?: equalization chargecausing standing voltagetodroop

Phil Marino-2
On Sat, Aug 1, 2009 at 11:37 PM, John O'Connor <[hidden email]>wrote:

> Hi Cor,
>
> I don't think I am lugging motor, I am in 2nd gear at this point. I
> will sometimes drop down into 1st the only effect is generally that I
> slow down. I basically need a lot of power to get up the hill.
>
> If I go with the lighter pack it will be the same interstate brand,
> just lower amp-hour capacity which drops lbs.
>
>
> John
>
>
> John -

 it seems to me that going with a smaller pack (fewer of the same batteries)
would just make things worse.   The total vehicle weight would not drop as
fast ( percentage-wise) as the drop in total battery capacity or pack
voltage. So you'd be drawing more battery current to climb the same hill at
the same speed that you do now.

The only time a smaller pack might help is if you were controller limited,
and not battery limited.  But, that doesn't sound like your situation.

Phil Marino
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Re: Experience?: equalization chargecausing standing voltagetodroop

John O'Connor-3

On Aug 1, 2009, at 11:55 PM, Phil Marino wrote:

> On Sat, Aug 1, 2009 at 11:37 PM, John O'Connor  
> <[hidden email]>wrote:
>
>> Hi Cor,
>>
>> snip
>>
>> If I go with the lighter pack it will be the same interstate brand,
>> just lower amp-hour capacity which drops lbs.
>>
>> John -
>
>  it seems to me that going with a smaller pack (fewer of the same  
> batteries)
> would just make things worse.   The total vehicle weight would not  
> drop as
> fast ( percentage-wise) as the drop in total battery capacity or pack
> voltage. So you'd be drawing more battery current to climb the same  
> hill at
> the same speed that you do now.
>
> The only time a smaller pack might help is if you were controller  
> limited,
> and not battery limited.  But, that doesn't sound like your situation.
>
> Phil Marino

My thinking is to trade off some range (amp-hours) to get better  
climbing performance by using 24 lighter 6 volt batteries.



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