Disclosed herein are a rechargeable battery jump starting device with a control switch (e.g. rotary control switch) and an optical position sensing switch system to determine a position of the control switch. The optical position sensing switch system includes an optical position sensor using optical coupling to insure an integrity of isolation on a 12V to 24V master switch to allow for a safe and effective operation, and configured so that a microcontroller unit reads a position on the master switch.