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Battery Switch

A battery cut off switch can help defend against theft while adding some badly needed protection for a catastrophic short circuit. There are a number of switch types on the market. The one shown (on right) is made by Pollak and is designed to be wall mounted. In this case it was mounted through the floor of the battery box. Sitting in the dark recess of the battery box it is very difficult to see unless you know what you are looking for. Access is not that easy but after some experience it becomes fairly painless. To seal the floor opening a large rubber washer was placed over the switch where it mates with the underside of the floor. The switch cuts off the ground wire link to the frame. On one pole is the ground wire from the battery. A second smaller wire is run back into the interior through a 20 amp breaker and then to ground. This keeps the circuit alive for the radio, alarm and so on. In the event of a short circuit or an attempt to start the car with the switch off the breaker will blow requiring a manual reset. The second pole has two cables running to the frame for ground. Twin cables were used as it was easier to route than a single heavier cable.