Li-Ion batteries are very dangerous if not handled properly .
DO NOT OVER CHARGE / BURN / OPEN Li-Ion Bats
Anything you do with this information is your own risk
Build a Li-Ion battery tester
I have so many old lap-top batteries around and some work better then others but I really wanted a way to measure each battery exact capacity and couldn't find anything on the web so I took the time (2 hours) and built my own.
Now I am sharing it with you all.
(The guy in the airport thought it was a bomb - wonder why...)
Step 1: Operating instruction
1. Set the clock to 12:00
2. Connect the battery to be tested (polarity is important)
3. Press the push-switch once
4. The two LEDS will turn on and the watch will start working .
5. After the LEDs turn off - check the watch reading and multiply it by 0.38 , that will give you the amount of Amp/Hour you have in this battery .