Measuring a 9 to 12.6V high current power source with Arduino

Hey everyone. I have three LiPo batteries in series that can output 36A and need to measure the voltage with arduino. A voltage divider wouldn't work because of the heat. How could I do this?

Use a voltage divider with a higher resistance. Learn to use Ohm's law before you start building your own (idiotic, dangerous...) circuits.