Installation of a 12-Volt Battery Switch

A battery switch will cut the power from the battery completely. This device is used primarily for race cars. The switch is placed in the rear of the car next to a taillight and accessible from the outside of the car. If the car rolls over or crashes, the engine can be shut off with this emergency battery switch. If placed under the hood, it must be distanced from any metal contact. That much amperage will cause a fire if it contacts the body or frame.

Drill a hole into the body at least one 1 from the taillight, sufficient to insert the switch rod. Drill two additional holes, using the holes in the mounting bracket for reference. Remove the switch knob with a Phillips head screwdriver.

Install the switch onto the body, with the switch rod protruding through the hole in the body. Insert the two bolts and nuts into the mounting bracket and tighten them with a wrench. Install the knob onto the switch rod from the outside of the body and tighten it with the screwdriver.

Run a length of 00-gauge wire from the battery's negative terminal all the way back to the cut-off switch. At the switch end of the wire cable, use wire cutters to strip the insulation off the end of the wire. Install a brass terminal end and squeeze it with pliers. Install it onto the left side of the switch by removing the nut on the terminal, sliding the wire onto the terminal and tightening the nut.

Drill a hole in the floor of the trunk. Cut a piece of the 00-gauge wire that will run from the switch through the floor to the closest spot on the frame. Install a brass terminal end on both ends of this wire and crimp them with pliers. Install the switch side of the wire onto the second terminal on the switch.


Look for a bolt or nut on the frame to place the wire terminal under. Use a wrench to remove the bolt or nut, then place the terminal under the bolt or nut and tighten it. If there is no convenient place to secure the wire terminal, drill a hole into the frame. Secure the lower ground terminal with a bolt and nut.