LI-ION Overcharge/Overdischarge Protector and Charger

[bartlettone]

Hello all,<p>I have recently acquired 10 Lithium Ion cells out of Nokia cellphone batteries. I don't know too much about this battery technology. I only know that they require overcharge/overdischarge protection and a special charging circuit that supplies constant current when the battery charge is low and a constant voltage when the battery charge is high.<p>Each cell is 4.1V @ 900mAh. I want to wire these cells in a series-parallel configuration with an output of 8.2V @ 4.5Ah. Each cell came with an external protection circuit. I decided to scrap these because they used proprietary Nokia components.<p>First, if it is even possible to wire these cells in the above mentioned configuration, I would appreciate any help in constructing a protection circuit for the entire battery pack. Help with a charging circuit would be much appreciated also.<p>Justin
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[Chris Smith]

To start with and not have to make a fast charger, Just trickle charge them at about 1/10 or 1/15 of the amp hour rating. This will be slow, but it will not hurt the battery. If you still want to build a fast charger, I'll look up a few chips or you can on the Maxim web site. Its complicated by comparison and Chips do it all these days.

[bartlettone]

Yes, I am looking for a fast charger. With the configuration I want to put these cells in, trickle charging would take a long time to charge a 4.5 Ah pack! <p>Also, Im looking for a way to implement an overcharge/overdischarge protection circuit for the entire pack. If anyone knows how to build one of these, let me know.<p>Appric.<p>Justin
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[Chris Smith]

Go to the MAXIM website for the chips.

[MrAl]

Hello again,<p>I agree, Maxim has a lot of chips for charging
Li-ion cells.
I noticed so does Linear, who has some rather
very low cost chips.<p>Good luck with it,
Al