Overview

No matter how good your battery-powered saw or drill is, sometimes you need a plug-in tool to get the job done. Don’t have an AC receptacle nearby? Well, if you have a truck, you already have most of the makings of a rolling AC generator. Just install an AC inverter and you’ll have about 1,800 watts at your fingertips. The basic setup runs about $450, and the upscale version (with auxiliary battery and isolator relay) about $700. The installation takes just a few hours and requires only a drill and hand tools.

Figure A: Complete system layout

Figure A: The complete system layout

Locate one fuse block between the main battery and the relay. Mount a second one after the relay. Install the third one between the auxiliary battery and the inverter.

 

Component shopping

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Photo 1: Thread the cables and connect

Pop 1-in. chase nipples into the holes in the bed and the box and spin on locknuts. Then push the "smurf" tube and cable through the nipples andconnect them to the inverter.

 

AC inverters come in two styles: modified and pure sine wave. A modified sine wave inverter (such as the AIMS No. PWRINV1800W; available from theinverterstore.com) is less expensive and works great with power tools. For “cleaner” power to run a computer, TV or portable tool battery charger, buy a pure sine wave inverter. Be sure it has built-in overload, over-temperature, over-and-under voltage and fault protection, as well as neutral isolation.

You’ll also need one 200-amp fuse block/fuse kit (two if you add a second battery and three if you add a battery isolator). Order separate lengths of 1/0 cable for the positive and negative connections. Adding a 100Ah valve regulated lead acid (VRLA) absorbed glass mat (AGM) battery is optional. It adds a few hundred dollars to the cost, but it helps prevent alternator overheating and helps maintain the voltage under heavy loads. Add an isolation relay at the same time to prevent draining your main battery.

Select a mounting location

Inverters create a lot of heat, so mount yours in a spot with adequate airflow like your truck bed toolbox or on the floor behind the driver's seat. Open the toolbox lid or the cab door when the inverter's in use.

Run the cabling

Every vehicle is different, so I can’t give you a “one-size-fits-all” wire routing scheme. But the most important rule is to keep both cables away from the engine block, pulleys, steering components, and the exhaust manifold and pipes. And run a separate negative cable from the inverter back to the main battery. To protect the cables under the vehicle, run them (especially the positive cable) inside flexible plastic 3/4-in. conduit. (This Carlon Flex-Plus Blue product, nicknamed “smurf” conduit by electricians, is available in 10-ft. lengths in the electrical department at home centers.) Then drill two 1-in. holes in the truck bed and two in the toolbox and install electrical fittings (Photo 1). Next, mount the inverter.

Mount the optional battery isolation relay under the hood and connect the trigger wire to a switch-powered “hot” wire. Install the optional auxiliary battery close to the inverter. See Figure A for the complete wiring diagram.

Finish the job at the battery

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Photo 2: Secure the fuse block

Clamp the cable ring terminals under the serrated washers and install the fuse. Then tighten the nut and install the protective cover.

 

Connect the positive cable to a fuse block before attaching it to the battery (Photo 2). Finish the job by connecting the negative cable to the battery.