Introduction: Add 120v Power to Your Vehicle With an Inverter

By Where The Highway Ends
About: I'm a journeyman Sheet Metal Mechanic with a passion for adventure and photography. Follow along with me on my Facebook page!

This guide is recommended as a supplement to the manual included with your power inverter. You should always read the manuals that come with your equipment.


Power Inverters are a great addition to any vehicle, if you're going on a roadtrip they're a must!

Power inverters take the 12 volts that your vehicle runs on and convert it to 120 volts like you have in your house. This allows you to power anything you want in your vehicle, provided that your inverter has a high enough output.

Depending on what you need mobile power for, you might be better off getting a Generator.

You can use them to do fun an unique things by bringing 120v power where your wouldn't normally find it, like making your own 'drive-in' movie theater:

https://www.instructables.com/id/Outdoor-Movie-Theater-With-Snow-Wall-and-Projector/

Now let's choose the right inverter!

Step 1: Choosing the Right Inverter

If you don't plan on running electronics with your inverter you don't need to worry too much about which type you choose.

However, if you are running electronics only buy one that says it's a Pure Sine Wave inverter. These are only slightly more money but provide a much more consistent voltage and won't damage your electronics like a cheaper inverter might.

Finding the right sized inverter is important. They can put added stress on the electronic system of your vehicle if you go too big

The alternator is the component already in your vehicle that creates 12 volt power. Generally, you should choose an Inverter than draws no more approximately 50% of what your alternator is rated for:

if your alternator is 80 amps you won't want to draw much more than 40 amps with your inverter.

40 amps @ 12v =480 watts. In this example, a 500 watt inverter is about as big as you should go.

A google search of your vehicle should tell you what size of alternator you have but, If you have any questions or would like help figuring this out I am more than happy to help. Just post in the comments or drop me a message.

Next let's decide where to mount it

Step 2: Choosing a Path for the Wiring and Mounting Location of Inverter

Heavy-Gauge wire is expensive so it pays to do a good job planning out your wiring path.

You'll want to keep the path as short as possible to save money and also keep your inverter operating as efficiently as possible.

I found a hole to pass my wiring through near the steering column of the truck. I mounted the inverter on the hump in between the front 2 seats.

Get a rough measurement of the distance between where you are placing the inverter and the battery terminals in your engine bay.

TIP: Be careful no to place the inverter where peoples feet will rest or where snow and water collects.

Let's choose the right wire

Step 3: Choosing the Right Wire

The last step should have given you a general idea of how much wire you'll need. But now we have to choose the right size of wire.

12 volt DC power doesn't like travelling long distances. The larger your inverter and the longer your wiring path is, the larger the diameter of your wire will need to be.

In the first step, you should have already determined the maximum size of inverter that your vehicle can handle.
(50% of vehicle alternator size)

Use the amperage and length of the wire with the chart above to figure out the Wire size (Gauge or AWG) to use.

If this is too complicated use these recommendations

  • 500 Watt or less inverter use 8 AWG wire
  • 500-800 use 6 AWG wire
  • 800-1000 Watt use 4 AWG wire
  • 1000-1500
  • 800-1000 Watt use 4 AWG wire

Don't forget to double you measurement because you'll need a positive and a negative wire to complete the circuit. Add an extra 20%-50% so you don't end up short

Next let's put together a shopping list

Step 4: Tools and Materials

Tools

  • Wire Strippers (a knife works but be careful)
  • Side cutters (for cutting wire)
  • Pliers
  • Cordless Drill
  • Step Bit (Drill bit used as a last resort if you can't find a suitable existing hole)
  • 5/16" chuck (also a handheld 5/16" driver can be helpful to have)

Materials (depending on the inverter you choose, the box may include wiring. If not you'll have to buy it)

  • Power Inverter (Pure Sine Wave unless you are sure you will never run electronics or charge batteries)
  • Wire (Use chart shown previously to determine what gage )
  • A circuit breaker or fuse (Generally it should be about 20% higher amperage that your inverter)
  • various crimp-on connectors sized to match your wire
  • Foil tape (used for heating and ventilation/ duct work)
  • Sheet Metal Screws for fastening inverter and circut breaker
  • zip ties or wire fasteners (optional, to keep the wire secure in position)

Time to start the install!

Step 5: Run Your Wire

Now that you have all the tools and materials that you should need for the job we're ready to start running wire.

You should have already chosen a path for your wiring so now all you need to do is pass the wire through the firewall of your vehicle. You should have found an existing hole to go through but if you didn't, take you step bit and drill one now. Be very careful that you know what is on both sides of where you are drilling.

When you pass the wire through make sure that it isn't in the way of any moving parts like brake, gas or clutch pedals or the steering column. It also will be bad news if it's too close to any hot components in the engine bay.

You must run two wires, one for the positive and one for the negative terminals. They many be slightly different lengths depending on the position of your battery terminals.

Place foil tape around the wire where it passes through the fire wall

Use zips ties or wire fasteners as needed to keep the wire secure in position.

Step 6: Add Eyelets

Once you're sure that your wire is routed to the correct locations cut it off an add your eyelets. Make sure you double check that your eyelets are the right size for the wire and for the terminal that they are going on.

Use electric tape to cover as much of the exposed wire and eyelets as you can.

Let's Install a Circuit Breaker to make our inverter more safe!

Step 7: Install Breaker

A breaker isn't required but it's nice to have. It will protect your vehicle in the event your inverter or wiring short circuits.

It is installed on wire coming from the positve (+ red) terminal on the battery. Install it as closely to the battery as possible.

Fasten the breaker to your engine bay using sheet metal screws.

Now we're ready to hook up all the wires!

Step 8: Hook Up Wires to Your Inverter

By now you should have all your wires routed and secure. Double check your routing and make sure that you are connecting the proper wires corresponding to positive and negative.

We're almost finished

Step 9: Hook Up to Your Battery and Test

You should have installed eyelets to your wires so that they can attach to your battery clamps. Remove the positive and negative clamps from your cars battery and add the wires for your inverter to the corresponding clamps. You should have chosen eyelets that match the bolt on the battery clamps. You will have to remove the nut completely to get them on.

Next we'll hook it all up and test the system

Step 10: Attach the Battery Clamps

It's time to hook your battery back up. Connect your positive clamp and then connect your negative clamp. If the breaker doesn't trip and you don't see sparks or smoke you're off to a good start.

Now plug something into your inverter and turn it on.

Congratulations you now have mobile power! Now go do something fun with it!