Abstract: A wheeled cabinet contains two internal booster batteries. Jumper cables are connectible to the booster batteries by a plug-and-socket connector. With the plug disconnected from the socket, end clamps of the jumper cables are applied across a battery or batteries of a vehicle to be jump started. Display lamps are actuated to indicate whether or not the polarity of the jumper cables as connected to the vehicle battery or batteries is correct and whether or not the connection points are appropriate for the potential (12 volt or 24 volt) which should be applied. When it is determined that the connection of the jumper cables to the vehicle batteries is correct, the plug is inserted into the socket to connect the booster batteries to the vehicle battery or batteries and permit jump-starting of the vehicle.