How do you charge up unprotected 18650 cells from 0V?

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Last seen: 8 years 10 months ago
Joined: 07/19/2012 - 03:35
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How do you charge up unprotected 18650 cells from 0V?

Hi all,

The reason why I am asking is… because I do have quite a bunch of them that are at 0V from laptop salvages. Reading around some old posts, it seems like in some cases it can be boosted back to life, so I figured maybe I should give it a shot!

Have you done it before? How did you go about it?

What I’ve read included things like:

1) hooking up the battery to a current generator set to a very low 50ma.
2) connecting the battery in parallel to a good battery, and slowly “jolt” it back to a more recoverable voltage using quick pulses.
3) by using a hobby charger, charge it up using the NiMh mode that ignores the low voltage cutoff
4) Apparently the Xtar SP2 seems able to do it too, but at 0.7ma (not even 1ma) I reckon it is going to take days just to wake a cell up, so perhaps I can do it faster Smile

Last seen: 1 hour 31 min ago
Joined: 01/20/2012 - 19:09
Posts: 1343
Location: Northern Europe

You don’t. Why risk your health, life and house just to save a couple of $?

Ford Prefect
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Last seen: 6 days 13 hours ago
Joined: 06/13/2011 - 08:07
Posts: 849
Location: Canada, eh!

If it is discharged that far, the cell is damaged and cannot be trusted. Also, even if you can charge it to 4->4.20V the capacity is going to be a tiny fraction of what it was, and the internal resistance will be higher. When a new, top of the line cell is less than $10 why risk it?

For me, any salvaged cells <3V are recycled.

Sardion Master
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Last seen: 9 years 4 months ago
Joined: 05/07/2012 - 19:54
Posts: 259
Location: Tennessee

I agree with the others on this ! Just don’t !!

I originally posted a pretty good description of safety protocol
if you wanted to try.

After further consideration I have deleted that info .

And tell you DON’T , it’s really not worth it…

Men occasionally stumble over the truth, but most of them pick themselves up and hurry off as if nothing had happened.

edc's picture
Last seen: 6 years 3 months ago
Joined: 01/16/2011 - 02:28
Posts: 3300

If the batteries are 0 they are no good. Even if you managed to charge them up they would not perform well. Why bother. Unprotected batteries are cheap. I salvaged some 5 year old sanyo batteries which were above 3 volt. They don’t run for very long and I would never use them in multi cell lights.

Last seen: 8 years 10 months ago
Joined: 07/19/2012 - 03:35
Posts: 118

Wow, reading all these stern warnings posted, I suppose it is a really bad idea…!

I’ve managed to befriend an local exporter of old laptops and he agreed to sell me old laptop batteries for a buck or so each, much cheaper than I can otherwise get them from eBay at, so I guess I don’t need to be so hardup about getting every last cell to work now! I’ll give it a shot and document it as I go along for other BLFers who might like to go this path to get their cheap 18650 fix Smile