Is it possible to repair lifepo4 cell that went below 2volts

[ebikedelight]

A friend of mine just had a cell ins his 48 volt lifepo4 pack go to 1.9 volts, in resting position. He charged it up fully, and it sagged back down to 3.2 volts over night , while all the other cells stayed at 3.3. volts.

Can this individual cell be repaired thru a few individual balance charges ?

 

[dnmun]

did the entire pack drain down or just the one cell is low? how did this occur and what BMS is he using?

you have to measure the cell voltages while the battery is on the charger at full charge.

 

[ebikedelight]

did the entire pack drain down or just the one cell is low? how did this occur and what BMS is he using?

you have to measure the cell voltages while the battery is on the charger at full charge.

1 cell went low...hes not using a BMS...he always relied on his controller to do a LVC at 42 volts.

 

[dnmun]

since he had no BMS to protect it from overdischarge the cell that is low was damaged when the cell was reversed so it will never really be able to work with the others.

he may have reversed even more cells than the one with the high internal resistance so i think he will have to devote a lot of time trying to figure out which were reversed and have to be replaced and which ones just were discharge to low voltages.

with pouch packs you can see the ones which are reversed because the puff up like balloons but with cylindricals all you can do is try to evaluate the internal resistance to charging which will require some skill and knowledge that i doubt he has.

but it is really pointless to work on it since he has no BMS to force it to balance now which is almost impossible even with a BMS with a high balancing current. so he took a good battery and made a bad battery from it. maybe his next battery will get a BMS because of this learning experience but i doubt it.

 

[dogman dan]

It might still be "usable" but for sure it will never be the same again. Entire pack will now have lower capacity due to one cell having less.