“This project is an Arduino circuit that monitors battery voltage and current with an ACS 712 module. The measurements are communicated over Bluetooth with an HC-05 module to an Android device. Basically you rewire the negative connection between your controller and battery to go through the ACS712 module. The Android app displays the battery status as well as current speed and distance traveled from the Android GPS The Android can be mounted to the bike in a weatherproof bag. The Arduino circuit is permanently mounted in a weatherproof box on the bike near the battery.”