AC External Charger From Cell Charger?

[asnider123]

Been thinking about charging batt in very small mod .. really not enough room for an internal circuit .. so here's the question ....

Many brands of cell phones have external AC adapters / chargers rated at 3.7v at 150-200 mAh ... are they really self-contained chargers? They do recharge the lithium ion batts inside the phone. Would they do the same on a 3.7v boxmod? Would you need any additional circuitry or could you just wire the external charger (thru a barrel-type power connector) across the battery?

Thanks for your feedback.

 

[CraigHB]

Should work. I haven't seen a cell phone charger myself like this, but you could just test it on an old Li-Ion cell. If it charges it to 4.2V, should be fine. Also check the current it's putting into the battery if you have a meter that can do that. Just to be sure.

The other thing you could do is use one of these. Hook it up to a USB wall wart then add another connector for your mod.

 

[mike20]

I use an Ego usb charger from MV 420 ma to charge an 18350 in a box I made myself. Just put a 510 connector on the box and some + - contacts inside. It works fine. about 5.50 for the charger.
If your battery is smaller you can get their charger that outputs less ma. -- less money also.
You could use a different type of connector if you open up the charger and tap + and -.

 

[WillyB]

Well the Motorola cell phone 'chargers' I have are just a dumb power supplies, AKA wall wart. The cell itself must do the dirty work.

They say on them "AC Power supply", output 5V 550mA. No Li-Ions should be charged at 5V.