Converting LI powered cell phone to alkali

Thread Starter


Joined Jan 12, 2013
I have a cheapy trac-fone who's charger just broke. So instead of buying a new charger for the price of a new phone, I have soldered wires to the + and - leads on the phone.

The phone uses a 3.7v 800mah litium ion battery. I suspect the battery actually charges to 4.?? volts.

I don't know the current draw of the phone so I can't be 100% sure on what to put in series with 3 AA cells to limit the voltage/current.

Any help on how to proceed is needed. I have minutes on the phone and want to keep them!


Joined Mar 14, 2008
Three NiMH batteries would have a series voltage of 3.6V which should power your phone just fine. You don't need to limit the current.

What's the voltage and current output of the charger. It shouldn't cost that much to get a new generic one.


Joined Feb 8, 2013

You might be making your very own charger. Just change the plug of the charger and resistors to get a regulated 4.2v. By the way, if you charge the Li-lion Battery while it is inside yor device, it means that there is a built in charger.In that case, 5 volt and 500 mA should be given to the device.

Hope it helps.