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How do I charge Li-ion Batteries? Answered

I have lots of old Li-ion batteries and I want to use the for a project. I want to put them all in parallel in a big pack and I need a charger that can charge them in a reasonable time. Can I just put 3.7v straight into them, with a current limiter of course, or do I need some special circuity with transistors etc. 

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prenato (author)2012-06-12

There's an excellent video tutorial on this subject from Dave at the eevblog:

http://www.youtube.com/watch?v=A6mKd5_-abk

As Steve mentioned above, charging Li-ion batteries is a bit more complex than other rechargeable types such as NiCd and Lead-acid. Fortunately there are ICs specifically designed for this. I tinkered with the idea of re-purposing an old charger for this purpose. You would have to identify the IC inside and make adjustments if needed though...

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steveastrouk (author)2012-06-10

Charging any batteries in parallel is usually a bad idea.

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user

ok, so say i just want to charge them all seperately, how would i do it?

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user

Build a specifically Li-on battery charger. The charge process is complex, and must terminate at the right point, or Re-Des video will happen.

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user

okay, guess ill have to take the hard option, damn. thanks anyway

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Re-design (author)2012-06-09

Put them out on the drive way away from cars etc and charge away.

Watch this video to find out why.

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