Lifepo4 36v Battery - did I ruin it?

gazzata

100 µW
Joined
Jul 12, 2021
Messages
9
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


Sent from my iPhone using Tapatalk
 
gazzata said:
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.
 
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.
d47615c5e25f9ef29d806211eb05f252.jpg



Sent from my iPhone using Tapatalk
 
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.
 
LewTwo said:
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?


Sent from my iPhone using Tapatalk
 
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.
 
gazzata said:
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?
 
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.


Sent from my iPhone using Tapatalk
 
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.
 
gazzata said:
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.


Sent from my iPhone using Tapatalk

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.
 
Thanks for advice everyone. May get a charger.


Sent from my iPhone using Tapatalk
 
Back
Top