Resurrecting seemingly-dead LiFePo4 cells.
February 5, 2024 8:55 AM Subscribe
My shelved collection of LiFePo4 (specifically not standard LiPo) 18650 cells have - all, confusingly - decided not to work for me.
What can I do to revive these cells, and where can I read about it?
They were stored safely and dry, so I'm not sure what brought this about - some of them have never been used - but here we are.
The charger that I have to hand is a Nitecore D2 that reports either nothing or ERR when I put these batteries into it. A multimeter reports them at zero. I don't have a bench power supply, but I'm willing to get one and accept a modest amount of risk if that's the right approach.
They were stored safely and dry, so I'm not sure what brought this about - some of them have never been used - but here we are.
The charger that I have to hand is a Nitecore D2 that reports either nothing or ERR when I put these batteries into it. A multimeter reports them at zero. I don't have a bench power supply, but I'm willing to get one and accept a modest amount of risk if that's the right approach.
Your life, your risk, assume the worst.
For a couple of overly discharged batteries I had, I essentially jump started them to knock the voltage up a bit, then flipped them back into the charger to handle the main charge.
So for an 18650 I think their operating range is 2.5v to 4.2v, so I'd be tempted to just put a bench charger to 3v, limit the current if possible to a trickle (0.3A?) and let them forcefully charge off that for a few minutes. Then flip them back over to the real charger, see if they take.
Since then I just bought a better charger, something built for RC enthusiasts (it's awful user-interface, so I won't recommend it by mentioning the model) which can more intelligently charge up a wider range of battery chemistries (and also discharge them to a certain voltage for storage).
posted by Static Vagabond at 11:44 AM on February 5, 2024
For a couple of overly discharged batteries I had, I essentially jump started them to knock the voltage up a bit, then flipped them back into the charger to handle the main charge.
So for an 18650 I think their operating range is 2.5v to 4.2v, so I'd be tempted to just put a bench charger to 3v, limit the current if possible to a trickle (0.3A?) and let them forcefully charge off that for a few minutes. Then flip them back over to the real charger, see if they take.
Since then I just bought a better charger, something built for RC enthusiasts (it's awful user-interface, so I won't recommend it by mentioning the model) which can more intelligently charge up a wider range of battery chemistries (and also discharge them to a certain voltage for storage).
posted by Static Vagabond at 11:44 AM on February 5, 2024
I've done similar to static vagabond, with both battery chemistries you reference in your question.
I have done it more recklessly (no current limiting) and it sometimes works. I always expect failure, so any success feels pretty good.
I'm also dumb enough to have done similar with a dead lithium cell jumped directly from an 18V drill battery, with variable success. That's a one second jolt and then a trip to the real charger.
I don't recommend it, but I do recommend eye protection for any of these choices.
posted by Acari at 2:31 PM on February 5, 2024 [1 favorite]
I have done it more recklessly (no current limiting) and it sometimes works. I always expect failure, so any success feels pretty good.
I'm also dumb enough to have done similar with a dead lithium cell jumped directly from an 18V drill battery, with variable success. That's a one second jolt and then a trip to the real charger.
I don't recommend it, but I do recommend eye protection for any of these choices.
posted by Acari at 2:31 PM on February 5, 2024 [1 favorite]
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posted by intermod at 9:12 AM on February 5, 2024