Recovery of under voltage cells.

[Pierre]

Has anyone successfully revived a faulty LiFe cell / cells that have dropped below 1v ?
2 of a batch of 28 cells arrived from CH in that state. Currently charging / discharging them to see if they will recover.
Any advice or comments are welcome.

 

[meetyg]

I haven't had such a situation myself, but there are some recommendations:
Charge them up slowly to 2.5v first.
You didn't mention the cells capacity, so I can really tell you how much amps...
But it should be pretty slow, in order not to cause further damage.
For large 200Ah cells and above, I would start with something like 1 amp (constant current).
When they reach 2.5v, try charging them to 2.8v with around 5-10% amperage of their capacity. Then disconnect the power supply and let them sit for an hour or so. Check the voltage: if it drops again below 2.5v, they are probably not recoverable.
If they hold voltage above 2.5v, you can charge them as usual up to 3.6v (or whatever top voltage you prefer, as long as it's within the cells specs).

The key here is to slowly charge the first part up to 2.5v. Be patient as it could take a while.

Good luck!

 

[Pierre]

Thanks for the advice. Will try that. The cells are 100Ah rating.