Lithium Ion Battery charger circuit

[Kool1zero]

Hey, anyone out there have a circuit that works well to charge a Lithium-Ion battery? I want to make a few battery chargers. something that I could leave a battery in and it wont ruin it. or take a battery out and it wont overheat or run wild or anything

what I'm thinking is kind of a docking station that I could put a spare phone battery onto and it could charge. after that, should I have a low battery, I might swap them out and then have the alternate battery charge.

See I have several batteries for my phone. Three to be exact. And a battery thats almost brand new that I have barely had occasion to use from my old phone. I want to charge these batteries and use the batteries in parallel to power a raspberry pi off of. always leaving one battery in the charger to power the pi.

I just think that I may be able to keep spare batteries for my phone charged and get a raspi running full time even when my car is off.



SO anyone know a circuit that will charge a battery and stop charging when it's full.

[hyper999]

There are loads of easy to find circuits out there for this sort of thing, just use google, here's an example where someone has made one and even made a dock for phone batteries to go with it.

http://dangerousprototypes.com/2013/02/04/open-source-diy-friendly-li-ion-charger/

[FOOKz™]

That MAX1555 chip is fantastic for charging lithium phone batteries. If you're thinking about charging the battery while its in use... then that will be a whole other ball game.

 I Totally recommend the MAX1555 from the article hyper posted.

Edit: I re-read your post kool1 and its no problem using lithium batteries in parallel... however you will run into trouble trying to charge the batteries in parallel. Each battery has its own internal resistance, so when you're changing multiple batteries together the resistance looks like a short-circuit to the charger.

Most chargers look for high internal resistance in the battery (fully charged battery) before it cuts power. If you have batteries charging in parallel then the charger will not see the high internal resistance of a fully charged battery... thus the charger continues to charge full batteries resulting in fire/explosion/leaking.