This is a device to test the voltage of a battery.
You will need:
3 330 ohm resistors
wires for the Arduino
Arduino programming software
Step 1: The Arduino Board
This is how i wired up the Arduino to the battery for testing how much voltage is in the battery. The light that lights up shows how much voltage is left in the battery.
Step 2: Coding the Arduino
This is the code that i used to program the Arduino with. Also you should scale the value of the voltage in your code to fit with the amount of voltage your batteries have. Once you get the Arduino wired up the right way and get all of that code slammed in there you are done and ready to test them batteries.