Re: Alibaba/Aliexpress Lithium

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Re: Alibaba/Aliexpress Lithium

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If the problem is charging, charging using multiple chargers will work.  If the problem is in discharge I don't know a solution.  Batteries in my scooter still at a proper voltage after charging.  I have only done a couple trips.  Nice not to see the voltage drop until a hill.  Lawrence Rhodes
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Re: Alibaba/Aliexpress Lithium

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Thank you everyone for the response so far, lots of information to
consider as usual. I currently running my boat at 48 volts but considering
running at 96 to reduce amperage, heat and a not so silent gear set.
Interesting on the 12v voltage limits Jay.  4 packs of 12v 100ah currently
look to be cheaper than a single 48v 100ah pack, likely due to the
popularity of 12v over 48v I suspect.  I currently use 4 x 12v 170ah
datacenter batts so I would likely have to run 8 x12v or 2 x 48 to keep
range up but more importantly the max discharge rate per cell in check.
These packs don't look to have much design around cooling.  It looks like
either 2 x 48 or 8 x 12 weight about the same, around 110lbs, which would
reduce weight by more than 360lbs over my leads  .

I have two really nice 17amp 48v Sevcon lead acid chargers,  would I be
able to use them with these Lithium packs (connected to match 48v of batts
of course)?

Cheers
Dan

On Mon, Mar 11, 2019 at 7:10 PM Lawrence Rhodes via EV <[hidden email]>
wrote:

> If the problem is charging, charging using multiple chargers will work.
> If the problem is in discharge I don't know a solution.  Batteries in my
> scooter still at a proper voltage after charging.  I have only done a
> couple trips.  Nice not to see the voltage drop until a hill.  Lawrence
> Rhodes
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Re: Alibaba/Aliexpress Lithium

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On 3/11/19 4:49 PM, Lawrence Rhodes via EV wrote:
> If the problem is charging, charging using multiple chargers will work.

Just make sure that the chargers are isolated if you are using them on
different parts of the same pack without breaking the pack up into
sections with a physical disconnect.

Jay
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Re: Alibaba/Aliexpress Lithium

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On 3/11/19 7:40 PM, Dan Baker via EV wrote:
>
> I have two really nice 17amp 48v Sevcon lead acid chargers,  would I be
> able to use them with these Lithium packs (connected to match 48v of batts
> of course)?
>

You can certainly hook up a Lead Acid battery charger to a Lithium
battery bank, and it will charge the cells as long as it's voltage is
above the battery bank voltage. Doing so is probably not safe however.

The trick is stopping the charge right when the cells are full, but not
overcharging them.  If you overcharge a flooded Lead Acid battery, it
bubbles a bit of Hydrogen out and the next time you top it up with
distilled water everything is good. (This is how they equalize all the
cells in a Lead Acid battery...they overcharge them all until they all
bubble....)

If you did the same to a lithium ion battery, it may burst into flames
very energetically, so your charger must be able to detect the voltage
level of every cell and stop charging the pack as soon as any cell
reaches it's "maximum" voltage.

Typically a "12 volt" charger will go up to 14.6 volts for a while to
equalize all six of the 2 volt cells in a lead acid battery, and then
drop down to 13.6 volts to maintain (float) the charge.)  In the same
way, a "48 volt" charger may actually go up to 58.4 volts.


You need to make sure that your "48 volt" lithium ion batteries can
safely be charged up to 58.4 volts (and that there is some way to make
sure that none of the cells are out of balance, because if even one cell
is too high, it may burst into flames....igniting other cells.....)

So, if you have a BMS that can turn a relay to turn off your
chargers...you probably could use those chargers to charge your
batteries safely. As long as the relay/bms worked every time.

Typically, a charger dedicated for LiIon batteries allows you to program
a specific stopping voltage (or comes pre-programmed for the appropriate
voltage of your pack.) They sometimes also have other safety features
such as automatically stopping after a set time limit, or a set number
of amp hours, or watt hours have been delivered, even if the voltage
hasn't reached the stopping point. They also usually have some way to
interact with a BMS (or a built in BMS) that allows them to stop
charging if any single cell within the pack goes above the max voltage
per cell.

Jay
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Re: Alibaba/Aliexpress Lithium

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Thank you again for the great info Jay.  Fire is never a good thing with
any vehicle and fires on boats are much worse than land vehicles, you
likely won't drown or your car wont sink if it catches fire.  Perhaps I can
install a trapdoor below my batts and eject them like a warp core on a Star
trek episode in a worse case scenario lol.   I do carry an extinguisher at
all times as per safe boating regulations, mine is 2x the min. size
required just in case.  I see a lot of these lithium batteries come with
chargers that are only 2 pin so I suspect they are a fixed top voltage and
an internal BMS to limit?   My Sevcons are isolated I know that, what I
don't know is if the top voltage can be changed.  They have an interface on
them which allows some settings but I could not find any documentation
online about them, Sevcon's website has nothing on them, may have to give
them a call.   I got them on a ebay deal clear out at a really good price.
If I don't charge with my Sevcons and use the included individual 12v
chargers, would there still be worry of connecting too many in series?  Is
it charging,discharging or both the issue when connecting in series?

Cheers
Dan

On Mon, Mar 11, 2019 at 9:18 PM Jay Summet via EV <[hidden email]> wrote:

>
>
> On 3/11/19 7:40 PM, Dan Baker via EV wrote:
> >
> > I have two really nice 17amp 48v Sevcon lead acid chargers,  would I be
> > able to use them with these Lithium packs (connected to match 48v of
> batts
> > of course)?
> >
>
> You can certainly hook up a Lead Acid battery charger to a Lithium
> battery bank, and it will charge the cells as long as it's voltage is
> above the battery bank voltage. Doing so is probably not safe however.
>
> The trick is stopping the charge right when the cells are full, but not
> overcharging them.  If you overcharge a flooded Lead Acid battery, it
> bubbles a bit of Hydrogen out and the next time you top it up with
> distilled water everything is good. (This is how they equalize all the
> cells in a Lead Acid battery...they overcharge them all until they all
> bubble....)
>
> If you did the same to a lithium ion battery, it may burst into flames
> very energetically, so your charger must be able to detect the voltage
> level of every cell and stop charging the pack as soon as any cell
> reaches it's "maximum" voltage.
>
> Typically a "12 volt" charger will go up to 14.6 volts for a while to
> equalize all six of the 2 volt cells in a lead acid battery, and then
> drop down to 13.6 volts to maintain (float) the charge.)  In the same
> way, a "48 volt" charger may actually go up to 58.4 volts.
>
>
> You need to make sure that your "48 volt" lithium ion batteries can
> safely be charged up to 58.4 volts (and that there is some way to make
> sure that none of the cells are out of balance, because if even one cell
> is too high, it may burst into flames....igniting other cells.....)
>
> So, if you have a BMS that can turn a relay to turn off your
> chargers...you probably could use those chargers to charge your
> batteries safely. As long as the relay/bms worked every time.
>
> Typically, a charger dedicated for LiIon batteries allows you to program
> a specific stopping voltage (or comes pre-programmed for the appropriate
> voltage of your pack.) They sometimes also have other safety features
> such as automatically stopping after a set time limit, or a set number
> of amp hours, or watt hours have been delivered, even if the voltage
> hasn't reached the stopping point. They also usually have some way to
> interact with a BMS (or a built in BMS) that allows them to stop
> charging if any single cell within the pack goes above the max voltage
> per cell.
>
> Jay
> _______________________________________________
> UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub
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> Please discuss EV drag racing at NEDRA (
> http://groups.yahoo.com/group/NEDRA)
>
>
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Re: Alibaba/Aliexpress Lithium

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Contrary to popular belief charging a Lithium Ion battery as little to do with the voltage of the charger.

Charging Lithium Ion batteries is a procedure when one holds the current constant until a voltage is reached and then holding the voltage constant letting current drop to a current cutoff value.

You can use any voltage over the max voltage of the cell while in constant current mode.

Any charger or power supply can do this the part it may not do is the constant voltage phase of the charge.

You could just skip the constant voltage phase and shutoff the charger when the voltage is reached. You will be over 90% charged at this point especially if you are using a low current.



Sent from my iPhone

> On Mar 12, 2019, at 9:59 AM, Dan Baker via EV <[hidden email]> wrote:
>
> Thank you again for the great info Jay.  Fire is never a good thing with
> any vehicle and fires on boats are much worse than land vehicles, you
> likely won't drown or your car wont sink if it catches fire.  Perhaps I can
> install a trapdoor below my batts and eject them like a warp core on a Star
> trek episode in a worse case scenario lol.   I do carry an extinguisher at
> all times as per safe boating regulations, mine is 2x the min. size
> required just in case.  I see a lot of these lithium batteries come with
> chargers that are only 2 pin so I suspect they are a fixed top voltage and
> an internal BMS to limit?   My Sevcons are isolated I know that, what I
> don't know is if the top voltage can be changed.  They have an interface on
> them which allows some settings but I could not find any documentation
> online about them, Sevcon's website has nothing on them, may have to give
> them a call.   I got them on a ebay deal clear out at a really good price.
> If I don't charge with my Sevcons and use the included individual 12v
> chargers, would there still be worry of connecting too many in series?  Is
> it charging,discharging or both the issue when connecting in series?
>
> Cheers
> Dan
>
>> On Mon, Mar 11, 2019 at 9:18 PM Jay Summet via EV <[hidden email]> wrote:
>>
>>
>>
>>> On 3/11/19 7:40 PM, Dan Baker via EV wrote:
>>>
>>> I have two really nice 17amp 48v Sevcon lead acid chargers,  would I be
>>> able to use them with these Lithium packs (connected to match 48v of
>> batts
>>> of course)?
>>>
>>
>> You can certainly hook up a Lead Acid battery charger to a Lithium
>> battery bank, and it will charge the cells as long as it's voltage is
>> above the battery bank voltage. Doing so is probably not safe however.
>>
>> The trick is stopping the charge right when the cells are full, but not
>> overcharging them.  If you overcharge a flooded Lead Acid battery, it
>> bubbles a bit of Hydrogen out and the next time you top it up with
>> distilled water everything is good. (This is how they equalize all the
>> cells in a Lead Acid battery...they overcharge them all until they all
>> bubble....)
>>
>> If you did the same to a lithium ion battery, it may burst into flames
>> very energetically, so your charger must be able to detect the voltage
>> level of every cell and stop charging the pack as soon as any cell
>> reaches it's "maximum" voltage.
>>
>> Typically a "12 volt" charger will go up to 14.6 volts for a while to
>> equalize all six of the 2 volt cells in a lead acid battery, and then
>> drop down to 13.6 volts to maintain (float) the charge.)  In the same
>> way, a "48 volt" charger may actually go up to 58.4 volts.
>>
>>
>> You need to make sure that your "48 volt" lithium ion batteries can
>> safely be charged up to 58.4 volts (and that there is some way to make
>> sure that none of the cells are out of balance, because if even one cell
>> is too high, it may burst into flames....igniting other cells.....)
>>
>> So, if you have a BMS that can turn a relay to turn off your
>> chargers...you probably could use those chargers to charge your
>> batteries safely. As long as the relay/bms worked every time.
>>
>> Typically, a charger dedicated for LiIon batteries allows you to program
>> a specific stopping voltage (or comes pre-programmed for the appropriate
>> voltage of your pack.) They sometimes also have other safety features
>> such as automatically stopping after a set time limit, or a set number
>> of amp hours, or watt hours have been delivered, even if the voltage
>> hasn't reached the stopping point. They also usually have some way to
>> interact with a BMS (or a built in BMS) that allows them to stop
>> charging if any single cell within the pack goes above the max voltage
>> per cell.
>>
>> Jay
>> _______________________________________________
>> UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub
>> http://lists.evdl.org/listinfo.cgi/ev-evdl.org
>> Please discuss EV drag racing at NEDRA (
>> http://groups.yahoo.com/group/NEDRA)
>>
>>
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Re: Alibaba/Aliexpress Lithium

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In reply to this post by Electric Vehicle Discussion List mailing list


On 3/12/19 9:59 AM, Dan Baker via EV wrote:

> If I don't charge with my Sevcons and use the included individual 12v
> chargers, would there still be worry of connecting too many in series?  Is
> it charging,discharging or both the issue when connecting in series?

That depends entirely upon the battery model/manufacturer and the specs
for that specific battery.  If there is an issue, it would most likely
be an issue for both charging and discharging.

The thing to watch out for is if the batteries have a MOSFET (solid
state switch) that is used to disconnect the battery when charging (done
charging, voltage too high) or when discharging (voltage too low).  In
many cases, the MOSFETS are not rated for super high voltages. It may be
twice the working voltage or much higher (24,36 or perhaps 60 volt
rated).  If your series pack goes above the MOSFET rating, it is likely
to fail spectacularly (short closed in the worst case) when it is asked
to disconnect the battery.

If the batteries use relays or contractors, they may or may not be rated
for higher series voltages, you need to verify.

In short, the electronics that are making these batteries "drop in
replacements" for a 12 volt battery are designed to work at that voltage
level...with perhaps  a 2x or 4x safety factor (24 to 48 volts), but the
system was not designed for high voltage (72-144 or higher) to be seen
by the battery.

The BattleBorn batteries for example use 60V electronics, and are rated
to be used in series up to a 48 volt system (They were designed this way
to be a drop in replacement for 12, 24, 36 and 48 volt solar power
systems....but many "auto starter" or RV replacement batteries gave no
thought about using more than one in series, or if they did, it was only
up to a 24 or 48 volt level.)

Jay

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Re: Alibaba/Aliexpress Lithium

Electric Vehicle Discussion List mailing list
I have been communicating with a couple sellers now on Aliexpress.  Prices
seem quite varied and reviews are mixed on these batteries.  I suspect
there isn't a lot of standards or testing on actual claimed capacities.  I
would like to try a 12v pack or 2 before buying more and perform some tests
to verify capacity.  Has anyone done this testing before?  I assume the ah
rating is based on a 1amp draw for x amount of claimed hours.  So would I
hook up a 12 watt load (LED bulbs?) and watch pack voltage till it drops
till below 12v?  Or would I measure it till the BMS protection cuts in -
(9-10v?).  Some reviewers have found packs listed at 100ah capacity to
actually have only 30ah cells inside, lots of misinformation.

Thank you,
Dan

On Tue, Mar 12, 2019 at 1:01 PM Jay Summet via EV <[hidden email]> wrote:

>
>
> On 3/12/19 9:59 AM, Dan Baker via EV wrote:
>
> > If I don't charge with my Sevcons and use the included individual 12v
> > chargers, would there still be worry of connecting too many in series?
> Is
> > it charging,discharging or both the issue when connecting in series?
>
> That depends entirely upon the battery model/manufacturer and the specs
> for that specific battery.  If there is an issue, it would most likely
> be an issue for both charging and discharging.
>
> The thing to watch out for is if the batteries have a MOSFET (solid
> state switch) that is used to disconnect the battery when charging (done
> charging, voltage too high) or when discharging (voltage too low).  In
> many cases, the MOSFETS are not rated for super high voltages. It may be
> twice the working voltage or much higher (24,36 or perhaps 60 volt
> rated).  If your series pack goes above the MOSFET rating, it is likely
> to fail spectacularly (short closed in the worst case) when it is asked
> to disconnect the battery.
>
> If the batteries use relays or contractors, they may or may not be rated
> for higher series voltages, you need to verify.
>
> In short, the electronics that are making these batteries "drop in
> replacements" for a 12 volt battery are designed to work at that voltage
> level...with perhaps  a 2x or 4x safety factor (24 to 48 volts), but the
> system was not designed for high voltage (72-144 or higher) to be seen
> by the battery.
>
> The BattleBorn batteries for example use 60V electronics, and are rated
> to be used in series up to a 48 volt system (They were designed this way
> to be a drop in replacement for 12, 24, 36 and 48 volt solar power
> systems....but many "auto starter" or RV replacement batteries gave no
> thought about using more than one in series, or if they did, it was only
> up to a 24 or 48 volt level.)
>
> Jay
>
> _______________________________________________
> UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub
> http://lists.evdl.org/listinfo.cgi/ev-evdl.org
> Please discuss EV drag racing at NEDRA (
> http://groups.yahoo.com/group/NEDRA)
>
>
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Re: Alibaba/Aliexpress Lithium

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I would recommend buying an inexpensive amp hour / voltage / watt hour
meter and using that to monitor the battery. (The one I use records the
data it has logged when power is removed, so that when you apply power
again the AH counter keeps the last reading.  You can also buy them with
relay outputs that allow you to program a "low voltage disconnect" to
act like a very basic BMS protection circuit...but the low voltages is
based off of the entrie pack, not the individual cells....)

This is the one I used on my last project:
https://www.amazon.com/gp/product/B07B4CWKRJ/ref=ppx_yo_dt_b_asin_title_o06_s00?ie=UTF8&psc=1

(It does not have relay outputs, but does support up to 200AH with it's
current sensor...which was important for my project).

You may wish to choose one with a 100 AH or lower current sensor if you
will be testing at lower currents, as the accuracy of the current
sensors is usually a percentage of their max rating. (Also note that a
shunt based current sensor is more accurate than these magnetic sensors
that you put the wire through, but if you are trying to get a very
accurate measure you probably are not buying $30 meters.....)

Jay

On 3/13/19 10:21 AM, Dan Baker via EV wrote:

> I have been communicating with a couple sellers now on Aliexpress.  Prices
> seem quite varied and reviews are mixed on these batteries.  I suspect
> there isn't a lot of standards or testing on actual claimed capacities.  I
> would like to try a 12v pack or 2 before buying more and perform some tests
> to verify capacity.  Has anyone done this testing before?  I assume the ah
> rating is based on a 1amp draw for x amount of claimed hours.  So would I
> hook up a 12 watt load (LED bulbs?) and watch pack voltage till it drops
> till below 12v?  Or would I measure it till the BMS protection cuts in -
> (9-10v?).  Some reviewers have found packs listed at 100ah capacity to
> actually have only 30ah cells inside, lots of misinformation.
>
> Thank you,
> Dan
>
> On Tue, Mar 12, 2019 at 1:01 PM Jay Summet via EV <[hidden email]> wrote:
>
>>
>>
>> On 3/12/19 9:59 AM, Dan Baker via EV wrote:
>>
>>> If I don't charge with my Sevcons and use the included individual 12v
>>> chargers, would there still be worry of connecting too many in series?
>> Is
>>> it charging,discharging or both the issue when connecting in series?
>>
>> That depends entirely upon the battery model/manufacturer and the specs
>> for that specific battery.  If there is an issue, it would most likely
>> be an issue for both charging and discharging.
>>
>> The thing to watch out for is if the batteries have a MOSFET (solid
>> state switch) that is used to disconnect the battery when charging (done
>> charging, voltage too high) or when discharging (voltage too low).  In
>> many cases, the MOSFETS are not rated for super high voltages. It may be
>> twice the working voltage or much higher (24,36 or perhaps 60 volt
>> rated).  If your series pack goes above the MOSFET rating, it is likely
>> to fail spectacularly (short closed in the worst case) when it is asked
>> to disconnect the battery.
>>
>> If the batteries use relays or contractors, they may or may not be rated
>> for higher series voltages, you need to verify.
>>
>> In short, the electronics that are making these batteries "drop in
>> replacements" for a 12 volt battery are designed to work at that voltage
>> level...with perhaps  a 2x or 4x safety factor (24 to 48 volts), but the
>> system was not designed for high voltage (72-144 or higher) to be seen
>> by the battery.
>>
>> The BattleBorn batteries for example use 60V electronics, and are rated
>> to be used in series up to a 48 volt system (They were designed this way
>> to be a drop in replacement for 12, 24, 36 and 48 volt solar power
>> systems....but many "auto starter" or RV replacement batteries gave no
>> thought about using more than one in series, or if they did, it was only
>> up to a 24 or 48 volt level.)
>>
>> Jay
>>
>> _______________________________________________
>> UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub
>> http://lists.evdl.org/listinfo.cgi/ev-evdl.org
>> Please discuss EV drag racing at NEDRA (
>> http://groups.yahoo.com/group/NEDRA)
>>
>>
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Re: Alibaba/Aliexpress Lithium

Electric Vehicle Discussion List mailing list
Yep Totally agree. I use several of these to monitor voltages and
currents in my DIY EV. Nice thing about them is that they work both ways
and will take into account regen and charging as well as discharge. I
found them to be as accurate as shunt based meters at a similar price
range BTW.


Steve

On 13/03/2019 17:39, Jay Summet via EV wrote:

> I would recommend buying an inexpensive amp hour / voltage / watt hour
> meter and using that to monitor the battery. (The one I use records
> the data it has logged when power is removed, so that when you apply
> power again the AH counter keeps the last reading.  You can also buy
> them with relay outputs that allow you to program a "low voltage
> disconnect" to act like a very basic BMS protection circuit...but the
> low voltages is based off of the entrie pack, not the individual
> cells....)
>
> This is the one I used on my last project:
> https://www.amazon.com/gp/product/B07B4CWKRJ/ref=ppx_yo_dt_b_asin_title_o06_s00?ie=UTF8&psc=1 
>
>
> (It does not have relay outputs, but does support up to 200AH with
> it's current sensor...which was important for my project).
>
> You may wish to choose one with a 100 AH or lower current sensor if
> you will be testing at lower currents, as the accuracy of the current
> sensors is usually a percentage of their max rating. (Also note that a
> shunt based current sensor is more accurate than these magnetic
> sensors that you put the wire through, but if you are trying to get a
> very accurate measure you probably are not buying $30 meters.....)
>
> Jay
>
> On 3/13/19 10:21 AM, Dan Baker via EV wrote:
>> I have been communicating with a couple sellers now on Aliexpress. 
>> Prices
>> seem quite varied and reviews are mixed on these batteries.  I suspect
>> there isn't a lot of standards or testing on actual claimed
>> capacities.  I
>> would like to try a 12v pack or 2 before buying more and perform some
>> tests
>> to verify capacity.  Has anyone done this testing before?  I assume
>> the ah
>> rating is based on a 1amp draw for x amount of claimed hours. So would I
>> hook up a 12 watt load (LED bulbs?) and watch pack voltage till it drops
>> till below 12v?  Or would I measure it till the BMS protection cuts in -
>> (9-10v?).  Some reviewers have found packs listed at 100ah capacity to
>> actually have only 30ah cells inside, lots of misinformation.
>>
>> Thank you,
>> Dan
>>
>> On Tue, Mar 12, 2019 at 1:01 PM Jay Summet via EV <[hidden email]>
>> wrote:
>>
>>>
>>>
>>> On 3/12/19 9:59 AM, Dan Baker via EV wrote:
>>>
>>>> If I don't charge with my Sevcons and use the included individual 12v
>>>> chargers, would there still be worry of connecting too many in series?
>>> Is
>>>> it charging,discharging or both the issue when connecting in series?
>>>
>>> That depends entirely upon the battery model/manufacturer and the specs
>>> for that specific battery.  If there is an issue, it would most likely
>>> be an issue for both charging and discharging.
>>>
>>> The thing to watch out for is if the batteries have a MOSFET (solid
>>> state switch) that is used to disconnect the battery when charging
>>> (done
>>> charging, voltage too high) or when discharging (voltage too low).  In
>>> many cases, the MOSFETS are not rated for super high voltages. It
>>> may be
>>> twice the working voltage or much higher (24,36 or perhaps 60 volt
>>> rated).  If your series pack goes above the MOSFET rating, it is likely
>>> to fail spectacularly (short closed in the worst case) when it is asked
>>> to disconnect the battery.
>>>
>>> If the batteries use relays or contractors, they may or may not be
>>> rated
>>> for higher series voltages, you need to verify.
>>>
>>> In short, the electronics that are making these batteries "drop in
>>> replacements" for a 12 volt battery are designed to work at that
>>> voltage
>>> level...with perhaps  a 2x or 4x safety factor (24 to 48 volts), but
>>> the
>>> system was not designed for high voltage (72-144 or higher) to be seen
>>> by the battery.
>>>
>>> The BattleBorn batteries for example use 60V electronics, and are rated
>>> to be used in series up to a 48 volt system (They were designed this
>>> way
>>> to be a drop in replacement for 12, 24, 36 and 48 volt solar power
>>> systems....but many "auto starter" or RV replacement batteries gave no
>>> thought about using more than one in series, or if they did, it was
>>> only
>>> up to a 24 or 48 volt level.)
>>>
>>> Jay
>>>
>>> _______________________________________________
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Re: Alibaba/Aliexpress Lithium

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On Wed Mar 13 11:06:36 PDT 2019 [hidden email] said:
>Yep Totally agree. I use several of these to monitor voltages and
>currents in my DIY EV. Nice thing about them is that they work both ways
>and will take into account regen and charging as well as discharge. I
>found them to be as accurate as shunt based meters at a similar price
>range BTW.

I use this one:
https://www.amazon.com/Programmable-Digital-meter-battery-monitoring/dp/B0043BDFYA/ref=sr_1_1

has 2 relay outputs, counts AH in both directions, uses a shunt for currents over 5A.
I've found it to be pretty accurate.


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Re: Alibaba/Aliexpress Lithium

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Thanks guys- never thought of this, I have a similar unit in my boat
already.  I typically use it just for monitoring amp output and volts.  I
have two throttles on my boat, a spring loaded Curtis-PB6 which I use for
docking/ maneuvering and a 5k knob style pot that I switch over for
cruise control, set the pot for desired amps/speed off of the gauge.  I'm
not sure if it will accurately pick up a small 1 amp load as it is rated
for up to 400 amps.  Anyone share what they used for a test load- a
resister or a bulb?  I assuming around 1 amp (12 watts) will be closest to
measuring true a/h readings.  Given that these lithiums only charge to 12.6
volts means my cut-off voltage will likely be closer to the stated BMS
cut-off, somewhere between 9-10 volts or when the voltage starts sharply
falling off?

On Wed, Mar 13, 2019 at 3:23 PM John Lussmyer via EV <[hidden email]>
wrote:

> On Wed Mar 13 11:06:36 PDT 2019 [hidden email] said:
> >Yep Totally agree. I use several of these to monitor voltages and
> >currents in my DIY EV. Nice thing about them is that they work both ways
> >and will take into account regen and charging as well as discharge. I
> >found them to be as accurate as shunt based meters at a similar price
> >range BTW.
>
> I use this one:
>
> https://www.amazon.com/Programmable-Digital-meter-battery-monitoring/dp/B0043BDFYA/ref=sr_1_1
>
> has 2 relay outputs, counts AH in both directions, uses a shunt for
> currents over 5A.
> I've found it to be pretty accurate.
>
>
> --
>
> Try my Sensible Email package!
> https://sourceforge.net/projects/sensibleemail/
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> http://groups.yahoo.com/group/NEDRA)
>
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Re: Alibaba/Aliexpress Lithium

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I think it would be better to measure at a higher amp rating if
possible. (Make your test go faster, and more accurately model the true
draw on the battery under load).

How many amps will the batteries see under your particular usage
scenario? If you can replicate that same amp draw (either with lots of
lights, a big resistor in a bucket of water or whatever....) it would
probably be the best test for your situation.  (Plus, if the amp draw is
higher, the precision of the amp meter would matter less....)

Jay

On 3/13/19 3:38 PM, Dan Baker via EV wrote:

> Thanks guys- never thought of this, I have a similar unit in my boat
> already.  I typically use it just for monitoring amp output and volts.  I
> have two throttles on my boat, a spring loaded Curtis-PB6 which I use for
> docking/ maneuvering and a 5k knob style pot that I switch over for
> cruise control, set the pot for desired amps/speed off of the gauge.  I'm
> not sure if it will accurately pick up a small 1 amp load as it is rated
> for up to 400 amps.  Anyone share what they used for a test load- a
> resister or a bulb?  I assuming around 1 amp (12 watts) will be closest to
> measuring true a/h readings.  Given that these lithiums only charge to 12.6
> volts means my cut-off voltage will likely be closer to the stated BMS
> cut-off, somewhere between 9-10 volts or when the voltage starts sharply
> falling off?
>
> On Wed, Mar 13, 2019 at 3:23 PM John Lussmyer via EV <[hidden email]>
> wrote:
>
>> On Wed Mar 13 11:06:36 PDT 2019 [hidden email] said:
>>> Yep Totally agree. I use several of these to monitor voltages and
>>> currents in my DIY EV. Nice thing about them is that they work both ways
>>> and will take into account regen and charging as well as discharge. I
>>> found them to be as accurate as shunt based meters at a similar price
>>> range BTW.
>>
>> I use this one:
>>
>> https://www.amazon.com/Programmable-Digital-meter-battery-monitoring/dp/B0043BDFYA/ref=sr_1_1
>>
>> has 2 relay outputs, counts AH in both directions, uses a shunt for
>> currents over 5A.
>> I've found it to be pretty accurate.
>>
>>
>> --
>>
>> Try my Sensible Email package!
>> https://sourceforge.net/projects/sensibleemail/
>> _______________________________________________
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>> http://groups.yahoo.com/group/NEDRA)
>>
>>
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Re: Alibaba/Aliexpress Lithium

Electric Vehicle Discussion List mailing list
Good points Jay.  I'm concerned with Peukert's law but if I could perform
under similar loads it would mean more to me and less to stated ah.  Both
would be ideal I guess- one for me and one for the evdl list.  But maybe
I'm the last guy here running lead so results given back wouldn't be of
much value here lol.

Thanks
Dan

On Wed, Mar 13, 2019 at 4:46 PM Jay Summet via EV <[hidden email]> wrote:

> I think it would be better to measure at a higher amp rating if
> possible. (Make your test go faster, and more accurately model the true
> draw on the battery under load).
>
> How many amps will the batteries see under your particular usage
> scenario? If you can replicate that same amp draw (either with lots of
> lights, a big resistor in a bucket of water or whatever....) it would
> probably be the best test for your situation.  (Plus, if the amp draw is
> higher, the precision of the amp meter would matter less....)
>
> Jay
>
> On 3/13/19 3:38 PM, Dan Baker via EV wrote:
> > Thanks guys- never thought of this, I have a similar unit in my boat
> > already.  I typically use it just for monitoring amp output and volts.  I
> > have two throttles on my boat, a spring loaded Curtis-PB6 which I use for
> > docking/ maneuvering and a 5k knob style pot that I switch over for
> > cruise control, set the pot for desired amps/speed off of the gauge.  I'm
> > not sure if it will accurately pick up a small 1 amp load as it is rated
> > for up to 400 amps.  Anyone share what they used for a test load- a
> > resister or a bulb?  I assuming around 1 amp (12 watts) will be closest
> to
> > measuring true a/h readings.  Given that these lithiums only charge to
> 12.6
> > volts means my cut-off voltage will likely be closer to the stated BMS
> > cut-off, somewhere between 9-10 volts or when the voltage starts sharply
> > falling off?
> >
> > On Wed, Mar 13, 2019 at 3:23 PM John Lussmyer via EV <[hidden email]>
> > wrote:
> >
> >> On Wed Mar 13 11:06:36 PDT 2019 [hidden email] said:
> >>> Yep Totally agree. I use several of these to monitor voltages and
> >>> currents in my DIY EV. Nice thing about them is that they work both
> ways
> >>> and will take into account regen and charging as well as discharge. I
> >>> found them to be as accurate as shunt based meters at a similar price
> >>> range BTW.
> >>
> >> I use this one:
> >>
> >>
> https://www.amazon.com/Programmable-Digital-meter-battery-monitoring/dp/B0043BDFYA/ref=sr_1_1
> >>
> >> has 2 relay outputs, counts AH in both directions, uses a shunt for
> >> currents over 5A.
> >> I've found it to be pretty accurate.
> >>
> >>
> >> --
> >>
> >> Try my Sensible Email package!
> >> https://sourceforge.net/projects/sensibleemail/
> >> _______________________________________________
> >> UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub
> >> http://lists.evdl.org/listinfo.cgi/ev-evdl.org
> >> Please discuss EV drag racing at NEDRA (
> >> http://groups.yahoo.com/group/NEDRA)
> >>
> >>
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Re: Alibaba/Aliexpress Lithium

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Also keep in mind that Lithium batteries, are not usually subject to
Peukert's law.  (Capacity loss due to high discharge rates is balanced
by voltage gain due to self heating.)

Jay

On 3/13/19 4:38 PM, Dan Baker wrote:

> Good points Jay.  I'm concerned with Peukert's law but if I could
> perform under similar loads it would mean more to me and less to stated
> ah.  Both would be ideal I guess- one for me and one for the evdl list.  
> But maybe I'm the last guy here running lead so results given back
> wouldn't be of much value here lol.
>
> Thanks
> Dan
>
> On Wed, Mar 13, 2019 at 4:46 PM Jay Summet via EV <[hidden email]
> <mailto:[hidden email]>> wrote:
>
>     I think it would be better to measure at a higher amp rating if
>     possible. (Make your test go faster, and more accurately model the true
>     draw on the battery under load).
>
>     How many amps will the batteries see under your particular usage
>     scenario? If you can replicate that same amp draw (either with lots of
>     lights, a big resistor in a bucket of water or whatever....) it would
>     probably be the best test for your situation.  (Plus, if the amp
>     draw is
>     higher, the precision of the amp meter would matter less....)
>
>     Jay
>
>     On 3/13/19 3:38 PM, Dan Baker via EV wrote:
>      > Thanks guys- never thought of this, I have a similar unit in my boat
>      > already.  I typically use it just for monitoring amp output and
>     volts.  I
>      > have two throttles on my boat, a spring loaded Curtis-PB6 which I
>     use for
>      > docking/ maneuvering and a 5k knob style pot that I switch over for
>      > cruise control, set the pot for desired amps/speed off of the
>     gauge.  I'm
>      > not sure if it will accurately pick up a small 1 amp load as it
>     is rated
>      > for up to 400 amps.  Anyone share what they used for a test load- a
>      > resister or a bulb?  I assuming around 1 amp (12 watts) will be
>     closest to
>      > measuring true a/h readings.  Given that these lithiums only
>     charge to 12.6
>      > volts means my cut-off voltage will likely be closer to the
>     stated BMS
>      > cut-off, somewhere between 9-10 volts or when the voltage starts
>     sharply
>      > falling off?
>      >
>      > On Wed, Mar 13, 2019 at 3:23 PM John Lussmyer via EV
>     <[hidden email] <mailto:[hidden email]>>
>      > wrote:
>      >
>      >> On Wed Mar 13 11:06:36 PDT 2019 [hidden email]
>     <mailto:[hidden email]> said:
>      >>> Yep Totally agree. I use several of these to monitor voltages and
>      >>> currents in my DIY EV. Nice thing about them is that they work
>     both ways
>      >>> and will take into account regen and charging as well as
>     discharge. I
>      >>> found them to be as accurate as shunt based meters at a similar
>     price
>      >>> range BTW.
>      >>
>      >> I use this one:
>      >>
>      >>
>     https://www.amazon.com/Programmable-Digital-meter-battery-monitoring/dp/B0043BDFYA/ref=sr_1_1
>      >>
>      >> has 2 relay outputs, counts AH in both directions, uses a shunt for
>      >> currents over 5A.
>      >> I've found it to be pretty accurate.
>      >>
>      >>
>      >> --
>      >>
>      >> Try my Sensible Email package!
>      >> https://sourceforge.net/projects/sensibleemail/
>      >> _______________________________________________
>      >> UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub
>      >> http://lists.evdl.org/listinfo.cgi/ev-evdl.org
>      >> Please discuss EV drag racing at NEDRA (
>      >> http://groups.yahoo.com/group/NEDRA)
>      >>
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Re: Alibaba/Aliexpress Lithium

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In reply to this post by Electric Vehicle Discussion List mailing list
Rated Capacity” is defined in the UN Model Regulations as follows: Rated capacity means the capacity, in ampere-hours, of a cell or battery as measured by subjecting it to a load, temperature and voltage cut-off point specified by the manufacturer.

You need to know how the manufacturer tested them and use the same process to see if they do as claimed.

Sent from my iPhone

> On Mar 13, 2019, at 3:45 PM, Jay Summet via EV <[hidden email]> wrote:
>
> I think it would be better to measure at a higher amp rating if possible. (Make your test go faster, and more accurately model the true draw on the battery under load).
>
> How many amps will the batteries see under your particular usage scenario? If you can replicate that same amp draw (either with lots of lights, a big resistor in a bucket of water or whatever....) it would probably be the best test for your situation.  (Plus, if the amp draw is higher, the precision of the amp meter would matter less....)
>
> Jay
>
>> On 3/13/19 3:38 PM, Dan Baker via EV wrote:
>> Thanks guys- never thought of this, I have a similar unit in my boat
>> already.  I typically use it just for monitoring amp output and volts.  I
>> have two throttles on my boat, a spring loaded Curtis-PB6 which I use for
>> docking/ maneuvering and a 5k knob style pot that I switch over for
>> cruise control, set the pot for desired amps/speed off of the gauge.  I'm
>> not sure if it will accurately pick up a small 1 amp load as it is rated
>> for up to 400 amps.  Anyone share what they used for a test load- a
>> resister or a bulb?  I assuming around 1 amp (12 watts) will be closest to
>> measuring true a/h readings.  Given that these lithiums only charge to 12.6
>> volts means my cut-off voltage will likely be closer to the stated BMS
>> cut-off, somewhere between 9-10 volts or when the voltage starts sharply
>> falling off?
>> On Wed, Mar 13, 2019 at 3:23 PM John Lussmyer via EV <[hidden email]>
>> wrote:
>>> On Wed Mar 13 11:06:36 PDT 2019 [hidden email] said:
>>>> Yep Totally agree. I use several of these to monitor voltages and
>>>> currents in my DIY EV. Nice thing about them is that they work both ways
>>>> and will take into account regen and charging as well as discharge. I
>>>> found them to be as accurate as shunt based meters at a similar price
>>>> range BTW.
>>>
>>> I use this one:
>>>
>>> https://www.amazon.com/Programmable-Digital-meter-battery-monitoring/dp/B0043BDFYA/ref=sr_1_1
>>>
>>> has 2 relay outputs, counts AH in both directions, uses a shunt for
>>> currents over 5A.
>>> I've found it to be pretty accurate.
>>>
>>>
>>> --
>>>
>>> Try my Sensible Email package!
>>> https://sourceforge.net/projects/sensibleemail/
>>> _______________________________________________
>>> UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub
>>> http://lists.evdl.org/listinfo.cgi/ev-evdl.org
>>> Please discuss EV drag racing at NEDRA (
>>> http://groups.yahoo.com/group/NEDRA)
>>>
>>>
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Re: Alibaba/Aliexpress Lithium

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To verify the factory AH rating you would measure at the same rate the
factory does. That's probably the 20 hour rate (C20; that is, current at
which they'll be flat in 20 hours).  

But you really don't (or shouldn't) care what the C20 capacity is.  All that
matters is how many AH (or WH) they'll deliver at the current your vehicle
actually requires.  

I'm far from a lithium expert, but as I understand it, generally lithium
batteries' capacity holds up better at higher currents, compared to lead
batteries'.  But IIRC you're looking at cheapies, so who knows.

BTW, watch out for recycled (used) cells in those cheap batteries.  As
anyone who does business in China regularly will tell you, it's still mostly
true that anything-goes-profit-above-all unrestricted capitalism and
stifling authoritarianism pick each others' fleas there.  Many Chinese
businesses will cut any and every corner to sell cheaply with the highest
possible profit.  Especially with no US quality control, there's no telling
what you'll get.  You might get lucky.  You might waste your money.

You don't always get what you pay for, but you very seldom get what you
DON'T pay for, and that goes triple for shady direct-import ¢r@p from China.

Good luck.

David Roden - Akron, Ohio, USA
EVDL Administrator

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Re: Alibaba/Aliexpress Lithium

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If you want to see whether a cell will last a long time you have to test it
in damaging conditions - full charge and high temps.

Cycling does nothing useful beyond allowing the cell to spend more time a
conditions that are not damaging at all. That's not really useful, but is
is what you will get from most low cost purveyors. When I tried to survey
vendors I got nowhere even finding out the test conditions.

If you could get tests that actually stress the cells you still have to
make comparisons between various cells to see if they are consistent in
withstanding the difficult conditions, or a particular brand or design is
better than another.

Your best bet is to go with a vendor and manufacturer that has a good
reputation, and that is likely not a low cost solution.

I am not sure about previous discussions and you may know this: Peukert's
Law is not applicable to Li ion cells in any way. It only relates to lead
acid cells.

If you nave not listened to lectures by Jeff Dahn you should to understand
how Li ion cells are damaged.
http://tinyurl.com/y395ahod
This 2013 lecture is worth spending time with on what causes Li ion cells
to die:
https://www.youtube.com/watch?v=pxP0Cu00sZs

On Thu, Mar 14, 2019 at 6:20 AM Dan Baker via EV <[hidden email]> wrote:

> I have been communicating with a couple sellers now on Aliexpress.  Prices
> seem quite varied and reviews are mixed on these batteries.  I suspect
> there isn't a lot of standards or testing on actual claimed capacities.  I
> would like to try a 12v pack or 2 before buying more and perform some tests
> to verify capacity.  Has anyone done this testing before?  I assume the ah
> rating is based on a 1amp draw for x amount of claimed hours.  So would I
> hook up a 12 watt load (LED bulbs?) and watch pack voltage till it drops
> till below 12v?  Or would I measure it till the BMS protection cuts in -
> (9-10v?).  Some reviewers have found packs listed at 100ah capacity to
> actually have only 30ah cells inside, lots of misinformation.
>
> Thank you,
> Dan
>
> On Tue, Mar 12, 2019 at 1:01 PM Jay Summet via EV <[hidden email]>
> wrote:
>
> >
> >
> > On 3/12/19 9:59 AM, Dan Baker via EV wrote:
> >
> > > If I don't charge with my Sevcons and use the included individual 12v
> > > chargers, would there still be worry of connecting too many in series?
> > Is
> > > it charging,discharging or both the issue when connecting in series?
> >
> > That depends entirely upon the battery model/manufacturer and the specs
> > for that specific battery.  If there is an issue, it would most likely
> > be an issue for both charging and discharging.
> >
> > The thing to watch out for is if the batteries have a MOSFET (solid
> > state switch) that is used to disconnect the battery when charging (done
> > charging, voltage too high) or when discharging (voltage too low).  In
> > many cases, the MOSFETS are not rated for super high voltages. It may be
> > twice the working voltage or much higher (24,36 or perhaps 60 volt
> > rated).  If your series pack goes above the MOSFET rating, it is likely
> > to fail spectacularly (short closed in the worst case) when it is asked
> > to disconnect the battery.
> >
> > If the batteries use relays or contractors, they may or may not be rated
> > for higher series voltages, you need to verify.
> >
> > In short, the electronics that are making these batteries "drop in
> > replacements" for a 12 volt battery are designed to work at that voltage
> > level...with perhaps  a 2x or 4x safety factor (24 to 48 volts), but the
> > system was not designed for high voltage (72-144 or higher) to be seen
> > by the battery.
> >
> > The BattleBorn batteries for example use 60V electronics, and are rated
> > to be used in series up to a 48 volt system (They were designed this way
> > to be a drop in replacement for 12, 24, 36 and 48 volt solar power
> > systems....but many "auto starter" or RV replacement batteries gave no
> > thought about using more than one in series, or if they did, it was only
> > up to a 24 or 48 volt level.)
> >
> > Jay
> >
> > _______________________________________________
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> >
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Re: Alibaba/Aliexpress Lithium

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Michael Ross via EV wrote:
> I am not sure about previous discussions and you may know this: Peukert's
> Law is not applicable to Li ion cells in any way. It only relates to lead
> acid cells.

I agree with the rest of what you said, but not with this. Peukert's law
says nothing about the chemistry involved; it applies to *all* types of
batteries and all chemistries.

Peukert's equation applies to any battery or cell that has internal
resistance, and that has a minimum "cutoff" voltage below which it is
harmed. It simply states that the higher the load current, the lower the
apparent amphour capacity. High currents cause a larger voltage drop, so
you reach the "cutoff" voltage before the cell is truly dead.

The amphours are not "missing"; you just can't get them without reducing
the load current, or pulling its voltage below the safe minimum. If
you're willing to shorten the life of the cell, you can still get it.

Peukert matters more for lead-acids because they typically have a higher
internal resistance. In particular, lead-acid internal resistance goes
up a lot as the cell approaches dead. Most other chemistries do not have
this large change in internal resistance as a function of state of charge.

--
Any intelligent fool can make things bigger, more complex, and more
violent. It takes a touch of genius, and a lot of courage, to move
in the opposite direction. -- Albert Einstein
--
Lee Hart, 814 8th Ave N, Sartell MN 56377, www.sunrise-ev.com
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Peukert (was: Alibaba/Aliexpress Lithium

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Diffusion rates are vastly less in Li-Ion. Thus, Puekert exponents are
very near unity (1.0).
Yes, there is some tiny effect, but no, the Puekert equation is not
really applicable.

The one hour capacity is essentially the same as the 20 hour capacity in
Li-Ion.

Bill D.

On 3/15/2019 3:19 PM, Lee Hart via EV wrote:

> Michael Ross via EV wrote:
>> I am not sure about previous discussions and you may know this:
>> Peukert's
>> Law is not applicable to Li ion cells in any way. It only relates to
>> lead
>> acid cells.
>
> I agree with the rest of what you said, but not with this. Peukert's
> law says nothing about the chemistry involved; it applies to *all*
> types of batteries and all chemistries.
>
> Peukert's equation applies to any battery or cell that has internal
> resistance, and that has a minimum "cutoff" voltage below which it is
> harmed. It simply states that the higher the load current, the lower
> the apparent amphour capacity. High currents cause a larger voltage
> drop, so you reach the "cutoff" voltage before the cell is truly dead.
>
> The amphours are not "missing"; you just can't get them without
> reducing the load current, or pulling its voltage below the safe
> minimum. If you're willing to shorten the life of the cell, you can
> still get it.
>
> Peukert matters more for lead-acids because they typically have a
> higher internal resistance. In particular, lead-acid internal
> resistance goes up a lot as the cell approaches dead. Most other
> chemistries do not have this large change in internal resistance as a
> function of state of charge.
>

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