Oops - fried a pair of 50AH LifeP04s - anyone got any?

[Swamplizard]

Hello everyone. I built two 12V LifePo4 batteries and connected them together for a nice 24V. Didnt realize a few were weak and when I connected the bank to my PIP LV2424 it fried two of the batteries (nice and swollen - oops). Anyone have a pair of 50AH batteries lying around for sale? Mine are Blue 5.25x7-inches. Would like to rebuild the 24V bank as a backup.

Thanks!

 

[schmism]

That sounds like you overcharged or over discharged the pack like your LV2424 settings were incorrect. Are you sure your settings are correct?

 

[Swamplizard]

Just unboxed it and assumed it had the right configs for charging ... my fault ... never assume. I also didnt have a 24v BMS (ordered but hadnt arrived) so again, my mistake. 6 of the 8 batteries seem to test fine and if I create 12V out of any 4 cells everything looks good. Just 2 swelled up badly and I assume are toast. I assume one cant fix them.

 

[Swamplizard]

Checked all the settings and it seems "in bounds" for my 24V battery pack...so a bit surprised this happened. I guess there must have been something wrong with the two batteries to begin with and the larger charger (it was charging at up to 30Amps) found the weak link.

If anyone has some local (not China) 50AH 3.2 in the 5.25x7-inch size please shoot me an email. Thanks!

 

[Swamplizard]

When I scan the top of the Battery I get 5516174A0185 which doesnt come up on Google as anything. Does someone have a secret decoder ring? Trying to find 2 of these cells. Thanks!!

 

[Hedges]

Hello everyone. I built two 12V LifePo4 batteries and connected them together for a nice 24V. Didnt realize a few were weak and when I connected the bank to my PIP LV2424 it fried two of the batteries (nice and swollen - oops).

I also didnt have a 24v BMS (ordered but hadnt arrived)

Checked all the settings and it seems "in bounds" for my 24V battery pack...so a bit surprised this happened. I guess there must have been something wrong with the two batteries to begin with and the larger charger (it was charging at up to 30Amps) found the weak link.

I think the only way that can work out OK is if all 8 cells start out about the same number of Ah away from full.
If all cells start to have voltage climb the top end of SoC curve at the same time, then the charge controller can stop at a suitable pack voltage without any cells being over-charged.
If two cells start at a higher SoC, then they run further up in voltage before pack voltage hits target.

That could happen if they were lower capacity, same capacity, or higher capacity than the rest. You could build a pack with two 280 Ah cells nearly full charge and 6, 50 Ah cells at lower state of charge, and still kill the higher capacity two. If all were top balanced the pack could probably work OK (bigger ones would have a different shape curve, however.)

Charge controller would have to be set to lower voltage if it was to have a chance of catching one or two runners while the other cells were at lower SoC.

 

[Swamplizard]

Thanks for the info Hedges. Sloppy of me tbh but will recover. I have 16 135AH coming for my actual production bank ... I just messed up my back-up 50AH bank and hope to find matching cells to rebuild it.