How to Hook Up a Battery Disconnect Switch

Racing cars is fun, and can provide a good outlet when done in a safe environment. But before you head off to the track to tear it up, you need to make your car safe. One safety feature available to race cars--as well as normal vehicles--is a battery disconnect switch. With one of these switches you can instantly cut power to the vehicle in case of a rollover or other accident. They're not difficult to install--it just takes a little bit of time and preparation.

Things You'll Need

• 4-gauge Battery cable, about 30 feet long
• Drill bits
• 3/8-inch ratchet and socket set
• Terminal crimper
• 4-gauge battery terminals with 1/2-inch holes
• Zip ties
• Wire stripper
• Wire cutter
• Marine-style positive battery terminal
• 1-inch rubber grommet

Instructions

1. Disconnect the negative terminal of the battery with the 3/8-inch ratchet.

2. Find a suitable location for the battery disconnect switch. This can be right up front on the bumper, or all the way in the back in the trunk. It depends on personal preference, or if you're racing the car, the rules of the particular organization you're racing with. Make sure you have enough room behind the panel to mount the switch and maneuver the terminals in place.

3. Drill a hole in the sheet metal using the drill and drill bits for the switch. Start with a smaller drill bit and progressively work your way up, which will help keep the panel in shape.

4. Mount the disconnect switch. Put it through the sheet metal so the switch is outside of the body and use the supplied mounting nut.

5. Do a test run of the battery cable so you can figure out what length you need. Run it through the areas you'll be running it for the final installation.

6. Remove the cable and strip the ends. Then crimp on the terminal end to both sides of the cable.

7. Bolt one end of the battery cable to the switch. Don't worry about which terminal it's installed on; it should work on both sides as it's just an on-off switch.

8. Run another length of battery cable from the switch to the accessories you need for the vehicle. This can be multiple lengths depending on your usage, and can go to the stereo, fuse power, starter and alternator, for example.

9. Run the cable for the final time and secure it to the vehicle with zip ties. The easiest way to do this is through the vehicle's interior, using a rubber grommet on the firewall and hiding the cable under the carpet. Of course if you don't have carpet, secure it where you can.

10. Bolt the marine-style battery terminal onto the battery post using the 3/8-inch ratchet and socket set.

11. Bolt the battery cable to the new terminal and reinstall the negative terminal. Now the switch is complete and should be operating correctly. Turn the switch to "on" and make sure the vehicle runs correctly.

Tips & Warnings

• If it won't start or work, test all of your connections and make sure they are secured properly. If you want to save wire, you may want to use a distribution block.

• Be careful when working with electrical connections. The voltage can shock you, and you can start a fire if you're not careful.

References

• Moroso Battery Disconnect Switches
• Stinger Distribution Block