Safe way to Recover from over-Discharge

[Thersom1948]

I have screwed up. Due to a combination of life circumstances, my DIY system got way over dischgarged.

1. are the cells going to be completely degraded now?

2. What is a safe way to recharge?

Since voltage is so low my AIO (Growatt) will not charge.

Can I connect my bench supply at 28V and charge for a while until it gets up enough to let the Growatt charge?

If I can avoid a full disassembly to top balance that would be nice, but if I have to I will do that.

The cells were well balanced before this happened

 

[LakeHouse]

I’ve seen worse here on the forum that have recovered just fine.
Hook up the bench power supply and charge with low current, maybe 2 Amps, until the cells are all back above 2.5V, then charge normally.

 

[Thersom1948]

Fantastic, thank you!

Will do that today and report back

For anyone wondering how I managed to do this: I have a small 12V fuseblock coming off the main disconnect separate from the BMS / AIO system.

All it has are a couple of USB plugs, but a small load (RPI Zero) was left plugged in for a long time and I didn't notice.