Bad battery or just cold weather?

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Bad battery or just cold weather?

Jay Summet
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In the summer I have driven my S-10 pickup conversion for trips of 17-20
miles and my Curtis charge meter has only dropped to the 6th or 7th LED
(in the yellow, not yet red).

I have 20 6volt Sams Club Energizer GC8 flooded batteries with a
PakTrakr to monitor them.

A few days ago I was on the 3rd day of a 12 mile trip [three 4 mile
commutes) (in weather that ranged from 65 F in the day to 35 F at night)
and around mile 11 I went up a good long hill.
That morning I had noticed that my charge meter was lower than I
expected for having only gone 8 miles and commented that it must be
because I was using the heater both mornings [it takes 8 amps at 120
volts, or 1kw), but the heater really doesn't take THAT much power, as
I'm only running it for 15 minutes or less each morning.

I've gone up this hill many times before, and this time the truck felt
decidedly underpowered. At the top of the hill I stopped at a store and
noticed the PakTrakr was giving me "Battery Failure" codes for my B5
battery.

I shopped for 30 minutes, and then limped the 0.75 mile home in first
gear around 20mph, watching battery B6's voltage with the paktrakr. I
saw it get down to 2.2 volts (out of 6!) when going up a small hill,
which worries me!  [The other 5 batteries on that remote were in the
4.0-5.0 volt range in that same timeframe...]

At the end of this 12 mile commute my curtis charge meter was down to
the 7th LED (still in the yellow, but about where I would expect for a
17-20 mile trip in the summer).

I charged battery B5 individually for 2 hours at 15 amps and then
charged the whole string. I also checked the water and connections on
B5, and they were fine.

The next morning I kept a close eye on B5 and it kept up with all of
it's neighbors on my daily 4 mile commute. That night I used my
individual charger to top up 4-5 batteries what had a 0.1v lower resting
state for about 30 minutes each and then fully charged the pack again.

On the next 4 mile commute battery B5 also appeared to be working just
like the others.  Next up, go two days without charging and see how it
holds up.

That 2.2 volt reading I briefly glimpsed on the paktrakr worries me
greatly, as it looks like the cell almost reversed. On the other hand,
it's possible that I misread it or the paktrakr just got confused. (on
the graphical display all the other 5 batteries were down at the bottom,
and when the battery read 2.2 volts the bar graph was all the way to the
top. (I figured it just dropped off the range and wrapped around
internally because the reading was so low..)

So, I'm wondering: Was the cold weather just reducing my range so much
that I hit the bottom (at least, on my "worst" battery). Or should I
start investigating replacing this battery under warranty (purchased in
February)?

[The voltage on this battery after a 4 mile commute is exactly the same
as many others in the pack...]

Jay

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Re: Bad battery or just cold weather?

EVDL Administrator
On 3 Dec 2011 at 6:29, Jay Summet wrote:

>
> I ... saw it get down to 2.2 volts (out of 6!) when going up a small
> hill ... The other 5 batteries on that remote were in the 4.0-5.0 volt
> range in that same timeframe...

Both are bad.  "Flat" for a 6v battery is defined as "reads under 5.25v
under the load you're applying."  In other words for good battery life no
battery in the pack should ever be allowed to fall under 5.25v under any
load.

>
> That 2.2 volt reading I briefly glimpsed on the paktrakr worries me
> greatly, as it looks like the cell almost reversed.

Be careful not to confuse the terms "cell" and "battery."  

The data quoted - a voltage 2v below the other batteries - suggest that you
did reverse one cell in that battery.  Good thing you were careful with the
current, or it might have turned into a "Trojan Teakettle" (a la Bob Rice).

That battery will now have lower capacity and a shorter life than the
others.  Most likely you'll be replacing it soon, I'm sorry to say.

David Roden - Akron, Ohio, USA
EVDL Administrator

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Re: Bad battery or just cold weather?

Roland Wiench
In reply to this post by Jay Summet
Hello Jay,

I would just replace the bad batteries.  Take them in to your battery dealer
and have them perform a load test (not with a engine load tester, or a
battery analyzer in the engine load tester mode ), but in a deep cycle load
mode.  It will have to be re-program to do a deep cycle load for this type
of battery.

These types of stores may not have the expertise to do this, so I bring in
my own equipment to do this test, plus I also use it to test new batteries
where the capacity and voltages are match.  If you need one or two
batteries, then try to find the batteries that will match your old set in
capacity and voltage and manufacturer date.

One time, I had one battery go bad in with one hour of usage in the EV.  I
had it replace with the same manufacture date, voltage and capacity that
came in the same pallet load of 40.

I also had one battery go bad in nine months.  Took it back to the dealer
and found one after searching through many batteries that match the same
date and capacity.  Normally a dealer is to return any battery that is over
three months old.  These batteries that are this old at the dealer should be
either charge every month or put on a battery maintainer.

The new set of 6 volt U.S. Batteries that I got back in Sept 4 2009, now
have 937 cycles on them and still read above the manufacturer rated
capacity.  I am charging this set every time I stop at a charging station
even if I only drive a mile which only takes about 6 to 9 minutes.

Roland




----- Original Message -----
From: "Jay Summet" <[hidden email]>
To: "Electric Vehicle Discussion List" <[hidden email]>
Sent: Saturday, December 03, 2011 4:29 AM
Subject: [EVDL] Bad battery or just cold weather?


> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA1
>
> In the summer I have driven my S-10 pickup conversion for trips of 17-20
> miles and my Curtis charge meter has only dropped to the 6th or 7th LED
> (in the yellow, not yet red).
>
> I have 20 6volt Sams Club Energizer GC8 flooded batteries with a
> PakTrakr to monitor them.
>
> A few days ago I was on the 3rd day of a 12 mile trip [three 4 mile
> commutes) (in weather that ranged from 65 F in the day to 35 F at night)
> and around mile 11 I went up a good long hill.
> That morning I had noticed that my charge meter was lower than I
> expected for having only gone 8 miles and commented that it must be
> because I was using the heater both mornings [it takes 8 amps at 120
> volts, or 1kw), but the heater really doesn't take THAT much power, as
> I'm only running it for 15 minutes or less each morning.
>
> I've gone up this hill many times before, and this time the truck felt
> decidedly underpowered. At the top of the hill I stopped at a store and
> noticed the PakTrakr was giving me "Battery Failure" codes for my B5
> battery.
>
> I shopped for 30 minutes, and then limped the 0.75 mile home in first
> gear around 20mph, watching battery B6's voltage with the paktrakr. I
> saw it get down to 2.2 volts (out of 6!) when going up a small hill,
> which worries me!  [The other 5 batteries on that remote were in the
> 4.0-5.0 volt range in that same timeframe...]
>
> At the end of this 12 mile commute my curtis charge meter was down to
> the 7th LED (still in the yellow, but about where I would expect for a
> 17-20 mile trip in the summer).
>
> I charged battery B5 individually for 2 hours at 15 amps and then
> charged the whole string. I also checked the water and connections on
> B5, and they were fine.
>
> The next morning I kept a close eye on B5 and it kept up with all of
> it's neighbors on my daily 4 mile commute. That night I used my
> individual charger to top up 4-5 batteries what had a 0.1v lower resting
> state for about 30 minutes each and then fully charged the pack again.
>
> On the next 4 mile commute battery B5 also appeared to be working just
> like the others.  Next up, go two days without charging and see how it
> holds up.
>
> That 2.2 volt reading I briefly glimpsed on the paktrakr worries me
> greatly, as it looks like the cell almost reversed. On the other hand,
> it's possible that I misread it or the paktrakr just got confused. (on
> the graphical display all the other 5 batteries were down at the bottom,
> and when the battery read 2.2 volts the bar graph was all the way to the
> top. (I figured it just dropped off the range and wrapped around
> internally because the reading was so low..)
>
> So, I'm wondering: Was the cold weather just reducing my range so much
> that I hit the bottom (at least, on my "worst" battery). Or should I
> start investigating replacing this battery under warranty (purchased in
> February)?
>
> [The voltage on this battery after a 4 mile commute is exactly the same
> as many others in the pack...]
>
> Jay
>
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> Version: GnuPG v1.4.10 (GNU/Linux)
> Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org/
>
> iEYEARECAAYFAk7aB/4ACgkQSWJjSgPNbM8SZgCdGm7Rfk/USXkYRlIgx7Ca70Pd
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> =6lIM
> -----END PGP SIGNATURE-----
>
> _______________________________________________
> | Moratorium on drag racing discussion is in effect.
> | Please take those discussions elsewhere.  Thanks.
> |
> | REPLYING: address your message to [hidden email] only.
> | Multiple-address or CCed messages may be rejected.
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Sams Club GC battery replacements?

Jay Summet
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Seeing as how one of my batteries may have a much reduced capacity
compared with the others, and it's only 10 months old, I'm considering
returning it for a replacement before it goes out of warranty.

I don't have my own battery load tester, and don't know that my local
Sam's club will either. (It does have a tire/battery shop as part of the
store.)

Has anybody returned a golf cart battery to Sams club within the
warranty period? Comments on procedures, things to ask for, etc?

Difficulty: A friend who has a Sams Club membership bought the batteries
for me. I have the receipt, but not a Sams club membership. Will I need
to get a membership to replace the battery?

Jay
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Re: Bad battery or just cold weather?

Jay Summet
In reply to this post by Roland Wiench
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On 12/03/2011 10:32 AM, Roland Wiench wrote:
> Hello Jay,
>
> I would just replace the bad batteries.  Take them in to your battery dealer
> and have them perform a load test (not with a engine load tester, or a
> battery analyzer in the engine load tester mode ), but in a deep cycle load
> mode.  It will have to be re-program to do a deep cycle load for this type
> of battery.

Do you have a recommendation for a specific one to buy/use?

I note that this one is inexpensive, but is probably does not have the
"deep cycle load mode" you mentioned...
http://www.samsclub.com/sams/shop/product.jsp?productId=prod862835&navAction=

>
> The new set of 6 volt U.S. Batteries that I got back in Sept 4 2009, now
> have 937 cycles on them and still read above the manufacturer rated
> capacity.  I am charging this set every time I stop at a charging station
> even if I only drive a mile which only takes about 6 to 9 minutes.
>

I may just start plugging in to charge after every small trip, even
though it takes a bit more power for the top-up charge.
Jay
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Re: Sams Club GC battery replacements?

Roland Wiench
In reply to this post by Jay Summet
Hello Jay,

No you do not have to be a member of Sams Club.  Just sign in as a guest at
the service counter. Show them your battery receipts.

The load tester you are showing is only for cranking type batteries which
normally is done for about 15 seconds.  The load elements in these types of
tester cannot withstand more than 15 seconds before it will trip out.

You can actually charge up a bad deep cycle battery and these types of
testers will show that battery good. A 6 volt battery may start out at 1000
MCA and after 200 charge cycles will increase to about 1100 MCA which is
consider the break in period.

In about 8 to 10 years, the battery gets down to about 500 MCA which may
reduce the range so you cannot drive around the block.

I use one of these old 6 volt batteries in my old tractor as a starter
battery.  It can crank for up to a minute and a load tester set for a
cranking type of battery will show good.

Sams Club when they first open, only did a cranking load test.  Our Sams
Club now does a long discharge at the 20 hour rate, but they stop it at 12
hours.

I said, my batteries are 250 AH and a 20 hour rate would be 12.5 amps.  I
normally drive my EV at 75 battery amps.  At 75 amps the Reserved Minutes is
150 minutes which would be discharge down to 0% State of Charge.

A 75 amp load test would have to run for 75 to 85 minutes to reach 50% SOC
which should be the cut off point.

At 75 amps at 75 minutes would be about 50% SOC.  To convert the Reserved
Minutes to Ampere Hour for my 250 AH battery with a Reserved Minutes of 150
Mins at 75 amps.

                    150 RM / 60 mins = 2.5 hours

                    2.5 hours x 75 amps = 187.5 AH at 0% SOC

                    187.5 AH /2 = 93.75 AH at 50% SOC or 1.25 hours


The tester I use is a Midtronics 640 Series Battery Conductance Analyzer
which is design 6 and 12 volt batteries. It can detect a bad cell, shorts
and loss of capacity.  I got it from my battery shop that uses this type and
a shop version which is use to match a pack of batteries for golf carts.

See:  http://www.midtronics.com

It is best to match a set of batteries not only by voltage, but by capacity.
Not good if one battery has a capacity of 800 MCA and another one is 1100
MCA which I seen in new batteries. The lower MCA rating will always be
undercharge and the higher MCA will be overcharge.  A BMS cannot balance
these two batteries that have that much difference.

My independent battery shop which I have been going to since the 50's will
sell me at or under the cost of a Sam's Club battery.

Roland


----- Original Message -----
From: "Jay Summet" <[hidden email]>
To: "Electric Vehicle Discussion List" <[hidden email]>
Sent: Saturday, December 03, 2011 5:40 PM
Subject: [EVDL] Sams Club GC battery replacements?


> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA1
>
> Seeing as how one of my batteries may have a much reduced capacity
> compared with the others, and it's only 10 months old, I'm considering
> returning it for a replacement before it goes out of warranty.
>
> I don't have my own battery load tester, and don't know that my local
> Sam's club will either. (It does have a tire/battery shop as part of the
> store.)
>
> Has anybody returned a golf cart battery to Sams club within the
> warranty period? Comments on procedures, things to ask for, etc?
>
> Difficulty: A friend who has a Sams Club membership bought the batteries
> for me. I have the receipt, but not a Sams club membership. Will I need
> to get a membership to replace the battery?
>
> Jay
> -----BEGIN PGP SIGNATURE-----
> Version: GnuPG v1.4.10 (GNU/Linux)
> Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org/
>
> iEYEARECAAYFAk7awZgACgkQSWJjSgPNbM/lkQCeOAkooDttDcZ/4XgB42WQnGcs
> 50YAnimBziI1//Tk8uZ5avXs7XRRODYb
> =rjk3
> -----END PGP SIGNATURE-----
>
> _______________________________________________
> | Moratorium on drag racing discussion is in effect.
> | Please take those discussions elsewhere.  Thanks.
> |
> | REPLYING: address your message to [hidden email] only.
> | Multiple-address or CCed messages may be rejected.
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>

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Re: Sams Club GC battery replacements?

Lee Hart
In reply to this post by Jay Summet
Jay Summet wrote:
> Has anybody returned a golf cart battery to Sams club within the
> warranty period? Comments on procedures, things to ask for, etc?

It was a long time ago, but I used Sam's Club 6v golf cart batteries in
my ComutaVan. One failed early, and they replaced it under warranty.
They didn't have any test equipment for it, and just took my word for it.

> Difficulty: A friend who has a Sams Club membership bought the batteries
> for me. I have the receipt, but not a Sams club membership. Will I need
> to get a membership to replace the battery?

Sounds like you'd better get your friend to go along with you. :-)

--
Lee A. Hart | Ring the bells that still can ring
814 8th Ave N | Forget the perfect offering
Sartell MN 56377 | There is a crack in everything
leeahart earthlink.net | That's how the light gets in -- Leonard Cohen

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Re: Sams Club GC battery replacements?

EVDL Administrator
In reply to this post by Roland Wiench
On 3 Dec 2011 at 19:37, Roland Wiench wrote:

> It is best to match a set of batteries not only by voltage, but by capacity.
> Not good if one battery has a capacity of 800 MCA and another one is 1100 MCA
> which I seen in new batteries. The lower MCA rating will always be undercharge
> and the higher MCA will be overcharge.

Maybe I'm missing something here.  I don't understand how you can measure a
battery's ability to deliver current and call it the battery's capacity.
Capacity is measured in amp-hours, not amps, no?

David Roden - Akron, Ohio, USA
EVDL Administrator

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Re: Battery capacity meter suggestion

Jay Summet
In reply to this post by Roland Wiench
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> The tester I use is a Midtronics 640 Series Battery Conductance Analyzer
> which is design 6 and 12 volt batteries. It can detect a bad cell, shorts
> and loss of capacity.  I got it from my battery shop that uses this type and
> a shop version which is use to match a pack of batteries for golf carts.
>
> See:  http://www.midtronics.com

That looks like a very nice unit. Unfortunately, the $400-$500 price
point is a bit out of my range, but it appears that the MDX-640 is their
cheapest model that works with 6v batteries. (All of their lower end
stuff is for 12v SLI's only...)


I guess if I really need to do load testing I'll just need to find a 75
Ah load, my voltmeter and a lawn chair...

Jay

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Re: Sams Club GC battery replacements?

Roland Wiench
In reply to this post by Jay Summet
Hello David,

Yes David,  The Ampere Hour is the Battery Capacity and it is a function of
Reserved Capacity and Amount of Ampere that can be discharge in a certain
amount of time.

Therefore we can use the formula of Reserved Minutes divided by 60 minutes
to get the number of hours it takes to discharge the battery to Zero Percent
State of Charge.

Then multiple the number of hours times the Battery Ampere Listed for the
Reserved Minutes of the battery and you get the Ampere Hour rating of the
battery.

The higher the battery ampere load is, than the shorter reserved time or run
time you will have. To shorten up the load testing of each battery in a
large pack of batteries we could use a battery tester that will indicate a
voltage drop in a shorter amount of time which compares the NO LOAD voltage
to a LOAD voltage.

Roland


----- Original Message -----
From: "EVDL Administrator" <[hidden email]>
To: "Electric Vehicle Discussion List" <[hidden email]>
Sent: Saturday, December 03, 2011 11:05 PM
Subject: Re: [EVDL] Sams Club GC battery replacements?


> On 3 Dec 2011 at 19:37, Roland Wiench wrote:
>
> > It is best to match a set of batteries not only by voltage, but by
> > capacity.
> > Not good if one battery has a capacity of 800 MCA and another one is
> > 1100 MCA
> > which I seen in new batteries. The lower MCA rating will always be
> > undercharge
> > and the higher MCA will be overcharge.
>
> Maybe I'm missing something here.  I don't understand how you can measure
> a
> battery's ability to deliver current and call it the battery's capacity.
> Capacity is measured in amp-hours, not amps, no?
>
> David Roden - Akron, Ohio, USA
> EVDL Administrator
>
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Re: Battery capacity meter suggestion

Lee Hart
In reply to this post by Jay Summet
Jay Summet wrote:
>> The tester I use is a Midtronics 640 Series Battery Conductance Analyzer...
>> http://www.midtronics.com

> That looks like a very nice unit. Unfortunately, the $400-$500 price
> point is a bit out of my range, but it appears that the MDX-640 is their
> cheapest model that works with 6v batteries. (All of their lower end
> stuff is for 12v SLI's only...)

Their website reeks of overblown hyperbole. "originator of modern
battery testing... unmatched experience... transcends the technology...
world leader in battery management..."

There is an understandable desire on the part of mechanics and repair
shops to have a small, light, fast way to test a battery. They want a
"little box" that you clip onto the battery that *instantly* tells you
its condition. Midtronics is trying to fill this need.

The problem is, you really *can't* tell the battery condition with a
quick test. They are measuring the battery's internal resistance. This
is easy; but it's a weak indicator of battery condition. It gives you a
hint; but not an honest answer.

It's like taking your kid's temperature to determine if he's sick. Might
work; might not; but it's quick and easy and makes you feel like you're
doing something.

> I guess if I really need to do load testing I'll just need to find a 75
> Ah load, my voltmeter and a lawn chair...

Unfortunately, you're right. The only way to know a battery's amphour
capacity is to MEASURE it. That requires connecting a load, and seeing
how long it can power it. No little tester with skinny test leads can do
this in a minute.
--
Lee A. Hart | Ring the bells that still can ring
814 8th Ave N | Forget the perfect offering
Sartell MN 56377 | There is a crack in everything
leeahart earthlink.net | That's how the light gets in -- Leonard Cohen

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Re: Battery capacity meter suggestion

drdhdmd
In reply to this post by Jay Summet
I'm jumping into this conversation in the middle but I have had  several
encounters with Midtronics testers and their company.
 
It seems that, as Lee Hart said, many shops like to attach an "analyzer" to
 a battery to quickly test it.  They key in a parameter such as 1000 for
the  cranking amps, attach the 18 gauge wire leads and press the button.  
After  20 seconds the battery tests good.  Trying to explain to the mechanic
that  this is not accurate is kind of a waste of time.  They won't believe that
 their expensive tester is wrong.
 
I thought I'd have better luck talking to the companies tech people.   No
luck.  They just kept spewing that they have done many tests on their  
analyzers and they are accurate.
 
When I ask them, why the tester said one of my 13 Deka 9A31 batteries was  
good when it could not supply 1000 amps for even one second they either
didn't  even understand the actual concept behind the term Cranking Amps or
where just  playing dumb to protect themselves.
 
 
Thank  you,

Dave Delman
1981 Electric DeLorean  Project
electricdelorean.com
http://evalbum.com/1482
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Re: Battery capacity meter suggestion

Cor van de Water
In reply to this post by Lee Hart
Lee wrote:
>It's like taking your kid's temperature to determine if
>he's sick. Might work; might not; but it's quick and easy
>and makes you feel like you're doing something.

Correct. It will detect a cold, not a broken finger.

Jay asked:
>> I guess if I really need to do load testing I'll just
>> need to find a 75 Ah load, my voltmeter and a lawn chair...
Lee answered:
>Unfortunately, you're right. The only way to know a battery's
>amphour capacity is to MEASURE it. That requires connecting a
>load, and seeing how long it can power it. No little tester
>with skinny test leads can do this in a minute.

When I wanted to load-test my batteries, I used two methods.
The first one was when I had one new UB121100 (12V 110Ah AGM)
and wanted to verify the manufacturer's claim that it could
deliver up to 80 Ah until dead. I had a long roll of copper
wire in my stack in the garage, I measured it and found out
that when I doubled it up, it would draw about 75A. It would
get hot, so I had to drape it all around my garage to allow
airflow to cool it (on the roll would have burned up) so it
was a good first shot at testing this one battery, but I had
to baby-sit it. Once did I forget and the battery went to a
too low voltage, which can damage cells (luckily in this case
it did not do much harm as confirmed in subsequent capacity
tests).
Later when I had a pallet with batteries, I wanted something
a little more automated, so I got a 12V DC to AC inverter
and plugged several 60W bulbs into it (I had converted most
lamps in my house to CFL so I had a stack of old bulbs) but
since this was a 600W inverter, I could not make it draw
more than about 40-50A continuous.
I also added a small AC to DC power supply that I had
lying around, plus a resistor, 3 series diodes and a
capacitor across the diodes. That was my 1.5V supply to
a cheap AA battery-operated wall clock, so all I needed
to do was to set the clock to indicate 12 o'clock as
starting point, connect a battery to the inverter, wait
until the lights went off and then read at what time
the clock had stopped. Multiply the time by the current
that was drawn (rule of thumb is to divide the Wattage
of the lamps by 10 to find the battery current) and that
gives a pretty reproducible discharge current and
capacity measurement.

Success,

Cor van de Water
Chief Scientist
Proxim Wireless Corporation http://www.proxim.com
Email: [hidden email]    Private: http://www.cvandewater.com
Skype: cor_van_de_water     XoIP: +31877841130
Tel: +1 408 383 7626        Tel: +91 (040)23117400 x203

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Re: Battery capacity meter suggestion

Roland Wiench
I have built one of these load tester using a high temperature stainless
welding wire that I got from a welding shop.  The wire I use was about 0.18
inch in diameter and 36 inches long.  Bench test the load of this wire, I
clamp both ends in a porcelain terminal strip and in series with a 100 amp
shunt for a 100 amp meter.

Connect to a Trojan T-145 6 volt battery , volt meter and use one of those
12 volt large red battery switches that are rated for 500 amps I got at a
auto parts store.

Using the full 36 inch length of wire, show about 40 amp load, so I shorten
up the wire until I can get a reading of 75 amp which was about 30 inches
long.

Install the components in a aluminum equipment box which I install the 30
inch wire on the two terminal strips, a shunt and amp meter, volt meter, a
plug to plug in a digital volt meter, a 100 amp 12 volt starter solenoid, a
on off switch and a momentary switch.

Also install another length of 30 inch stainless steel wire that I can
connected in series with the other 30 inch for 12 volt battery testing.

According to the Trojan engineer I talk to, use this tester to find a bad
battery out of the pack and/or compare the voltage drop to the other
batteries in the pack.

Start with a full charge battery or about 6.37 volts and apply the load
until voltage reads about 6.01 volts.  Remove the load and the voltage
should rise to at least above 6.3 volts.

If the voltage drops below 6.01 volts very fast then you may have a bad
battery.  Then you can try to do a longer load test on this battery, but do
not allow it to drop below 5.25 volts.

I normally did this test once a month on the Trojans from 2000 to 2009 until
6 batteries would drop very fast when the voltage is going below 6 volts, by
the time I could shut off the tester, the voltage would be down to 4 volts.

Went to the battery shop to see about a new battery pack.  The dealer gave
me the portable battery analyzer to check all the batteries in the EV and it
read out BAD BATTERY on the six that check out bad with my equipment.

Replace all the 30 batteries with U.S. Batteries and the remaining Trojan
batteries are now being use in another EV. I use this battery analyzer to
check my batteries every month and not about to take 30 hours for using the
75 amp load test and another 30 hours to charge each battery after each test
every month.

What I am looking for is a battery that is not match with the other
batteries in the pack.

Roland


----- Original Message -----
From: "Cor van de Water" <[hidden email]>
To: "Electric Vehicle Discussion List" <[hidden email]>
Sent: Sunday, December 04, 2011 11:32 PM
Subject: Re: [EVDL] Battery capacity meter suggestion


> Lee wrote:
> >It's like taking your kid's temperature to determine if
> >he's sick. Might work; might not; but it's quick and easy
> >and makes you feel like you're doing something.
>
> Correct. It will detect a cold, not a broken finger.
>
> Jay asked:
> >> I guess if I really need to do load testing I'll just
> >> need to find a 75 Ah load, my voltmeter and a lawn chair...
> Lee answered:
> >Unfortunately, you're right. The only way to know a battery's
> >amphour capacity is to MEASURE it. That requires connecting a
> >load, and seeing how long it can power it. No little tester
> >with skinny test leads can do this in a minute.
>
> When I wanted to load-test my batteries, I used two methods.
> The first one was when I had one new UB121100 (12V 110Ah AGM)
> and wanted to verify the manufacturer's claim that it could
> deliver up to 80 Ah until dead. I had a long roll of copper
> wire in my stack in the garage, I measured it and found out
> that when I doubled it up, it would draw about 75A. It would
> get hot, so I had to drape it all around my garage to allow
> airflow to cool it (on the roll would have burned up) so it
> was a good first shot at testing this one battery, but I had
> to baby-sit it. Once did I forget and the battery went to a
> too low voltage, which can damage cells (luckily in this case
> it did not do much harm as confirmed in subsequent capacity
> tests).
> Later when I had a pallet with batteries, I wanted something
> a little more automated, so I got a 12V DC to AC inverter
> and plugged several 60W bulbs into it (I had converted most
> lamps in my house to CFL so I had a stack of old bulbs) but
> since this was a 600W inverter, I could not make it draw
> more than about 40-50A continuous.
> I also added a small AC to DC power supply that I had
> lying around, plus a resistor, 3 series diodes and a
> capacitor across the diodes. That was my 1.5V supply to
> a cheap AA battery-operated wall clock, so all I needed
> to do was to set the clock to indicate 12 o'clock as
> starting point, connect a battery to the inverter, wait
> until the lights went off and then read at what time
> the clock had stopped. Multiply the time by the current
> that was drawn (rule of thumb is to divide the Wattage
> of the lamps by 10 to find the battery current) and that
> gives a pretty reproducible discharge current and
> capacity measurement.
>
> Success,
>
> Cor van de Water
> Chief Scientist
> Proxim Wireless Corporation http://www.proxim.com
> Email: [hidden email]    Private: http://www.cvandewater.com
> Skype: cor_van_de_water     XoIP: +31877841130
> Tel: +1 408 383 7626        Tel: +91 (040)23117400 x203
>
> _______________________________________________
> | Moratorium on drag racing discussion is in effect.
> | Please take those discussions elsewhere.  Thanks.
> |
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