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Discharged to 8v

carbon12

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Nov 5, 2019
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Hi
Through carelessness I allowed a 12v LiFePO4 battery to discharge to 8v a few days ago :rolleyes:. Normally I use it to power some equipment while camping, charging it with a Victron Blue Smart IP22 at 15A or 30A.

I am wondering what I should do now. I see my options as:
1. Treat it as a functional write off, due to internal damage that will stop it working with a useable capacity.
2. Treat it as a safety write off, due to internal damage potentially creating a hazard for sensitive equipment powered by it or to people (gassing, heat, internal short, whatever).
3. Attempt a resuscitation with gentle charging and accept the capacity is likely reduced , but potentially still a useful amount, and use it in the same way as I did in the past (but with more secure protection obviously).

Any advice welcome. Links to authoritative studies/sources about this would also be v welcome.

Cheers
Richard
 
just apply a charge to it, NOT a heavy high amp one ! if you can 15A is likely just right. It will be SLOW and will require monitoring and it will generate more heat from being at such a low SOC. Once you get to 3.000Vpc (12.0V) let it settle for an hour without charge, recheck and if still above 2.75Vpc / 11.0V (it will settle of course) then you can charge up to full as usual.
 
It does depend a bit on how long it stayed at 8V. And I ask also, What happened to the BMS?
 
Just a thought, at 8v, are you 100% shure the BMS is active/on?
There was not a BMS fitted at the time. I have been meaning to fit one for ages, just didn't get round to it before I fluffed it. I used a BattGo to monitor the cells and do top balancing. I just underestimated the power drain this time - like I said, a careless mistake.
 
just apply a charge to it, NOT a heavy high amp one ! if you can 15A is likely just right. It will be SLOW and will require monitoring and it will generate more heat from being at such a low SOC. Once you get to 3.000Vpc (12.0V) let it settle for an hour without charge, recheck and if still above 2.75Vpc / 11.0V (it will settle of course) then you can charge up to full as usual.
Thanks Steve, I'll give it go. Just checked it, the voltage is now 11.37 after standing disconnected for a couple of days so not as bad as I first feared.
 
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