how to recharge a discharged lithium battery?

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spacejim asked Dec 7, '21

how to recharge a discharged lithium battery?

I have a 300ah victron lithium battery, and a smart BMS CL 12/100 setup in a van. While I was on holiday it has discharged and I can now only bluetooth connect to the BMS.

The BMS reads the battery at only 3.5v. I usually charge it by hooking up a mains charger to the van battery, which then goes through the BMS as "alternator" charging. But now that does nothing, the BMS says alternator charging is "disabled by the battery". How can I wake it up? Should I directly put a mains lithium smart charger on it and ignore the BMS?

battery charging BMS

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Answer 1 · 2021-12-07T17:12:40Z

markus answered · Dec 07, 2021 at 05:12 PM

Your battery is now deep discharged and damaged.

It is not safe to recharge the battery once it was in this state. Even if you bring the battery back to life, by charging it with a charger ignoring the BMS, cell chemistry has changed. This change could damage the separator, leading to a cell internal self discharge resulting in smoke, fire and evil.

Sorry for the bad news.

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Answer 2 · 2021-12-07T17:41:11Z

spacejim answered · Dec 07, 2021 at 05:41 PM

Damn I was afraid of that. My other question is HOW did it happen in just over a week it went from fine all the way down to 3.5v? There was nothing but a computer fan running on it, through a batteryprotect, and an inverter with no loads on it. Even then isn't it supposed to protect itself from that sort of thing? Could it have been a defect maybe?

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