Cell phone battery useful capacity testing


Flashlight Enthusiast
Mar 1, 2007
Naoussa Greece
hi all!

I was called to find a replacement battery for a family member's phone, and in the process I thought of measuring the useful capacity of the cells, cos it turned out there are 3 phones with the same battery +1 spare around the family.

I am pretty confident i have the processes alright cos i am already doing it with Li-Ion batteries

Asumming proper pinout, I intend:

1- hook a LED and a one chip 7135 driver on the battery and measure time. 350mA is 1/3 of the rated capacity and I am not shooting for precision

2- test internal resistance with a power resistor.
i will be starting low and maintain drain at 0.5C

Am I wrong in my plan?