How to Wire an Extra 12 Volt Outlet in a Car

by Ed English
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Adding an extra 12 volt outlet really comes in handy when you want to plug in that charger and the other outlet is being used. Wiring the outlet is simply a matter of connecting a positive and negative wire from the battery to the back of the outlet. Add an inline fuse in the positive wire and attach the negative wire to ground for safety. Test the outlet and you are finished.

Step 1

Investigate the area behind the panel where you plan to install the outlet. Make sure there is enough room for the outlet to fit and be mounted. Outlets have different mechanisms used for mounting. It may have a ring behind it that must be screwed or a spring clamp that must be compressed to hold it in place. Some outlets are held in place with screws located in front at each side of the outlet.

Step 2

Drill a small pilot hole in the panel where the outlet is located. Drill a larger hole, the same size as the outlet diameter.

Step 3

Install and route two wires from the outlet location to the battery location. Use wire fasteners to secure the wire in place every few inches to avoid chafing the wire insulation and to keep it in place. Leave several extra inches on both ends for ease of installation and possible future needs.

Step 4

Crimp the positive and negative wires to the corresponding wire leads at the back of the outlet. Wrap each connection separately and securely with electrical tape. Mount the outlet onto the panel according to the manufacturer's instructions.

Step 5

Install the inline fuse holder in the positive wire at your desired location. Do not install the fuse at this time. Attach the positive wire to the positive post of the battery. Attach the negative wire to the negative post of the battery or to a common ground location. Insert the fuse into the fuse holder and test the outlet.

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