Lifepo4 36v Battery - did I ruin it?

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gazzata   100 µW

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Lifepo4 36v Battery - did I ruin it?

Post by gazzata » Jul 25 2021 3:16am

Being of an impulsive nature (assemble flat pack>read instructions > disassemble flat pack > reassemble flat pack - you get the idea) I bought a Lifepo4 36v battery two years ago, cycled it maybe four times then it stopped working. Life got in way etc. Now I have recharged it and it is reading 34v on multimeter but when attached does not fire up system. Cycle Analyst does not start up etc. In fact when I attach it to a 36v Led lamp it barely illuminates and across the terminals it reads 16v. Then take lamp off it reads 34v again.

After all that I do my research. Turns out, as you all knew, you need a special charger for a Lifepo4 battery. Doh! So my question is:

Will the right charger solve the issue or is the battery trashed?

All thoughts gratefully received.

Gary


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LewTwo   100 kW

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Re: Lifepo4 36v Battery - did I ruin it?

Post by LewTwo » Jul 25 2021 3:49am

gazzata wrote:
Jul 25 2021 3:16am
After all that I do my research. Turns out, as you all knew, you need a special charger for a Lifepo4 battery.
Not really special but you do need the correct charge voltage.
Fortunately LiFEPO4 batteries are harder to ruin than typical Lithium Ion cells.

You actually need to provide a bit more information:
Is 36 volts its nominal voltage?
That would indicate: 12 cells in series, charge at 43.5 volts, max = 42 volts, min = 30 volts

As you did not mention it, I assume that you are using it with a built in BMS.
I would be suspicious of the BMS ... could also be a bad cell/cell string.
You may need to perform a battery autopsy and check the voltage for each cell/cell string.
The more I learn the more obvious the immensity of my ignorance becomes.
Weight Wennie E-Bike https://endless-sphere.com/forums/viewt ... 3#p1173723
Shaft Drive Grocery Getter https://endless-sphere.com/forums/viewt ... =6&t=90718
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gazzata   100 µW

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Re: Lifepo4 36v Battery - did I ruin it?

Post by gazzata » Jul 25 2021 4:16am

Hi

Thanks so much for that. Info available is minimal. It is nominal 36v and max charge v is 43.8

Not sure about the internals. Assume there is a BMS.

Pic attached. Image


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LewTwo   100 kW

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Re: Lifepo4 36v Battery - did I ruin it?

Post by LewTwo » Jul 25 2021 4:25am

Well if you use a charger with the correct voltage and still have the problems that you spoke of then I suspect you are going to have to put it under the knife.
The more I learn the more obvious the immensity of my ignorance becomes.
Weight Wennie E-Bike https://endless-sphere.com/forums/viewt ... 3#p1173723
Shaft Drive Grocery Getter https://endless-sphere.com/forums/viewt ... =6&t=90718
...and thanks to Justin!

gazzata   100 µW

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Re: Lifepo4 36v Battery - did I ruin it?

Post by gazzata » Jul 27 2021 2:57am

LewTwo wrote:Well if you use a charger with the correct voltage and still have the problems that you spoke of then I suspect you are going to have to put it under the knife.
Thanks LewTwo

Can I just check-I have charged it fully with the same charger I got with my 36v nominal Li-ion charger and it is still funky. Does the Lifepo4 need a different kind of charger?


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LewTwo   100 kW

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Re: Lifepo4 36v Battery - did I ruin it?

Post by LewTwo » Jul 27 2021 4:41am

Lithium Cobalt (aka Lithium Ion) Lithium Iron Phosphate have different charge phases, voltage, etc.
Ironically LiFePO4 is simpler and much closer to Lead Acid than than to LiCo in that regard.
The more I learn the more obvious the immensity of my ignorance becomes.
Weight Wennie E-Bike https://endless-sphere.com/forums/viewt ... 3#p1173723
Shaft Drive Grocery Getter https://endless-sphere.com/forums/viewt ... =6&t=90718
...and thanks to Justin!

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E-HP   100 MW

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Re: Lifepo4 36v Battery - did I ruin it?

Post by E-HP » Jul 27 2021 9:02pm

gazzata wrote:
Jul 25 2021 3:16am

Will the right charger solve the issue or is the battery trashed?
Even if the charger you're using is for a 36V lithium ion pack, it would still have enough voltage to partially charge your pack (42V vs. 43.8V). It may be possible that the pack is really out of balance, but based on your description, it could be dead. You'd need the right charger to attempt to balance it, but might be money down the drain if the pack can't be revived. Didn't it originally come with a charger?

gazzata   100 µW

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Re: Lifepo4 36v Battery - did I ruin it?

Post by gazzata » Aug 01 2021 5:32am

No it didn’t. I got it from Crystalyte Europe. It is charged to 34v according to the multimeter. And even if I set min voltage really low on the cycle analyst with another battery, the system still is not fired up with the Lifepo4. How can something read 34v but fail to power the system up or even light a 36v bulb? Weird.


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Voltron   100 MW

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Re: Lifepo4 36v Battery - did I ruin it?

Post by Voltron » Aug 01 2021 10:58am

It could either be a bad BMS, or a bad group. The meter doesn't pull much load so you're seeing a voltage reading, but as soon as there's load it's maybe making a low group sag enough to trigger a safety cutout, or the BMS is jacked.

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E-HP   100 MW

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Re: Lifepo4 36v Battery - did I ruin it?

Post by E-HP » Aug 01 2021 11:30am

gazzata wrote:
Aug 01 2021 5:32am
No it didn’t. I got it from Crystalyte Europe. It is charged to 34v according to the multimeter. And even if I set min voltage really low on the cycle analyst with another battery, the system still is not fired up with the Lifepo4. How can something read 34v but fail to power the system up or even light a 36v bulb? Weird.


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Since the pack has never been balanced, or fully charged from day one, it could be way out of balance. You could try getting the right charger and leave it charging for a few days to see if it will balance.

gazzata   100 µW

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Re: Lifepo4 36v Battery - did I ruin it?

Post by gazzata » Aug 01 2021 11:32am

Thanks for advice everyone. May get a charger.


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