How to wire a car inverter to a car battery

Updated March 23, 2017

Automotive power inverters convert the DC voltage of the car battery to the 120 volt AC that household appliances use. They are becoming increasingly common as an aftermarket upgrade for automobiles, and provide a convenient method for powering your devices that you just can't leave at home. Installation of some inverters is as simple as plugging the unit into a 12 volt receptacle in your car. Other units are a little more tricky and require that you hard-wire them into the battery. All inverter installations carry a certain amount of danger.

Choose where you want your inverter to be. Ideally you want the unit to be in an area that will allow it to remain cool, dry, and protected from any cargo or people that might damage it. The closer the unit is to the battery, the better. At this point you should choose the route that your power cables will take to the battery.

Remove any interior trim pieces that you need to in order to run your wire, and drill any holes that the wire will run through. Put rubber grommets in the holes you drilled to protect the power cables. The length of wire you need is determined by your particular set-up, but the manual of the inverter generally specifies the gauge of the wire.

Run each wire separately from the unit to the battery. As you run the wire, mark half of the wires with black electrical tape wrapped around both ends so that you can easily determine which one is the ground wire. Cut each wire 30 to 60 cm (1 to 2 feet) too long on each end just in case you make a mistake later. Replace trim pieces and anchor the wire to the body of the car wherever it is exposed and not secured by the trim. Mount your inverter as directed by the manufacturer's instructions in the manual.

Cut the wire that you marked with tape to an appropriate length, and strip 1.2 cm (1/2 inch) of insulation off the ends with the strippers or a utility knife. This will be the negative, or (-), cable. Slip a protective rubber boot over both ends of the wire (usually included in the kit). Fit a wire ring terminal onto the end of the wire intended to connect to the battery, and crimp securely with the wire crimping tool. You can now screw these ends onto the negative terminal of the battery and inverter.

The remaining wire will be the positive, or (+), cable. Prepare it the same as the negative cable, but do not yet connect it to the unit or the battery. Locate a space in the engine compartment somewhere along the length of the positive cable where you can mount the fuse box. Cut the positive cable in this spot and attach the fuse box to the positive cable. Some fuse boxes just require the wire to be stripped and screwed in. Others require you to prepare the ends with rubber boots and ring terminals, but you already know how to do that now. Anchor the fuse box to the car using the screws that came with it.

Attach the positive cable to the inverter unit, and then finally the battery. Make sure that a fuse is in place in the fuse box, and test the unit.


Be careful not to screw into any wires when replacing the trim pieces or anchoring the wire to the car body.


Never allow anything to short across the battery terminals. This can cause bad shocks, or explosions. Do not connect the positive cable to the battery until the very end; this minimises the chance of a short, shock or fire occurring during the project.

Things You'll Need

  • Drill
  • Phillips head bit
  • Flathead bit
  • Power inverter kit
  • Drill bit(s)
  • Rubber grommets
  • Heavy gauge wire
  • Wire cutters
  • Fuse and fuse block (if not included in kit)
  • Protective rubber boots for wire (if not included in kit)
  • Wire ties or clips
  • Ring wire terminals
  • Wire crimping tool
  • Adjustable spanner
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About the Author

Rebecca Burdick began her freelance writing career in 2007 and currently writes for several online publications. She specializes in small business bookkeeping and financial management. Burdick studied accounting and economics at Boise State University and University of California at Riverside.