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.

Things You'll Need

• Main battery cut-off switch.
• Drill
• Pliers
• Set of wrenches
• Ratchet
• Set of sockets
• Wire cutters
• Phillips head screwdriver
• Bolts and nuts
• Negative battery terminal
• Brass battery cable ends
• Roll of 00-gauge wire
• 120-volt electrical outlet box

Instructions

Trunk-mounted Switch

1. 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.

2. 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.

3. 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.

4. 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.

5. 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.

Underhood-mounted Switch

1. Install the switch onto the passenger's side fenderwell close to the battery. The 120-volt socket outlet box housing has one open side where the socket will go, and the back of the box has punch-out metal plugs where the wires will enter. It is essentially a three-sided box. The center plug must be punched out.

2. Remove the knob from the switch by removing the screw that holds it onto the rod with a Phillips head screwdriver. Insert the rod through the punched-out hole. Position the switch into the box so that when it is secured, the two terminals are as far as possible from the sides. Drill holes into the box to coincide with the holes in the switch.

3. Insert the two bolts and nuts and tighten them with a wrench to secure the switch to the box. Hold the box on the best mounting location on the fenderwell. Trace the holes in the box to the fenderwell. Remove the box and drill the holes.

4. Cut off the old battery's positive cable terminal and install a brass terminal. Crimp it with pliers. Install this end on the back of the switch onto one of the terminals and tighten it.

5. Run a length of 00-gauge wire from the switch to the positive terminal on the battery. Use the wire cutters to strip the insulation off the end of this wire and install a brass terminal end and crimp it with pliers. Install this end onto the positive battery terminal and tighten it with a wrench.

6. Align the holes in the box with the holes you drilled out. Insert the bolts through the box and continue through the fenderwell. Install the nuts and tighten them to secure the box to the fenderwell.