[john61ct]

All in one string, no paralleling?

Have you balanced them, or verified they are balanced against each other? At what SoC point?

Have you cap tested each?

 

[john61ct]

You are very likely damaging them further charging them like that.

3S means do not go past 10.5V, if CC/ Bulk stage only, at maximum 80A.

10.35V would be better if you want precision, holding that (Absorb / CV cycle) until current drops below say 5A.

Then isolate each cell,

record voltage of each with a known accurate DMM

let sit a few hours, ideally 24 or more

then record them again and report back.

Also, meantime start cap testing on the ones you think are OK.

Best if you started getting better gear, really want an electronic dummy load that will do single cells,

or a good hobby charger that can do a decent discharge rate.