Abstract: A battery jumper cable system wherein an alarm is provided upon initial misconnection of the system cables to a first-connected battery, or upon subsequent misconnection of one of the system cables to a second-connected battery. The system includes principal conductors for connection to the terminal posts of the batteries, and an auxiliary conductor for connection to the frame or ground terminal of the second-connected battery. An alternative embodiment provides for two auxiliary conductors whereby either end of the cable system can be connected to either battery.