Adding 120V AC Power To a Truck Bed (Part 4)

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The Project In Review

Where Do I Get All This Cool Stuff?

For those who are unfamiliar with my vehicle-improvement articles, I’d like to mention my standards for my projects’ suppliers:

  1. The product quality must be first-rate. Simply put, my truck cost a lot of money, is important to me, and I don’t feel like spending my time putting junky accessories on/in it. This is doubly the case for something like electrical components, upon which I might rely heavily while out in the field, and can be dangerous if poorly manufactured. I’d hate to have a weekend trip ruined because a cruddy piece of equipment went south on me.
  2. They must have a strong online presence. This isn’t just because I’m a bit of a techno-nerd (which I freely admit to being); it’s also because I want to may access FAQs, technical support, product diagrams, installation guides, user forums and the like at 3 AM on the Saturday of Labor Day weekend.
  3. They must not laugh at me when I tell them what I’m doing. Seriously, customer service is a huge issue with me.

In short, I want to be as proud of my suppliers as I am of my project. I’m happy to say that all of my suppliers for this project met and/or exceeded even my high expectations. The components in this installation are absolutely the finest available, each company has a strong web site with adequate (or more than adequate) online support, and they all were extremely helpful in all phases of the project. At the end of my projects, I like to be able to recommend highly the companies whose products I used. And such is certainly the case with this project: I would use any of these suppliers again in a heartbeat.

The centerpiece of this project is, of course, the power inverter: this was the most expensive compenent and probably the one with the widest variety of sizes and options. After considering several worthy candidates, I decided on a 1600 watt unit from Dimensions Unlimited. They offer a wide variety of inverters that are marketed for applications in industrial, marine, and vertical markets. All of their inverters are also UL-listed for land vehicle use, so I figured that their products would be robust enough and safe for this application.

This unit is also one of the few I found that included built-in AC receptacles (which is common but not universal) and a battery charger, which allows me to plug the truck into a garage receptable to recharge the batteries. The model I chose also features a fast-transfer option, which enables the inverter to switch power sources quickly enough to avoid interruption of most electronic equipment.

I found the most appealing conduit and fittings at Electri-Flex. Electri-Flex makes a wide variety of flexible conduits, for all kinds of applications. After a chat with their very helpful manager of engineering, we concluded that the Corrlok® system, a simple liquid-tight Nylon conduit, would suit my installation. Their conduit is lightweight, strong and flexible, and their fittings come in a variety of choices to suit almost any application.
After some diligent googling for toolboxes, I found a company called Highway Products that makes a wide variety of very robust boxes for all kinds of trucks. Highway Products uses .125" aluminum for the box structure and .100" diamond plate aluminum for their lids; this was the thickest material used in tool boxes that I could find. It was also clear from details on their web site that their boxes are very well constructed. I decided on their gull-wing saddle-box model, since it opens from the sides of the truck, permits easy access into the box and leaves room underneath in the bed. The finish on this box is absolutely beautiful, as the photos show.
For the deep-cycle battery bank, I chose Optima Batteries "yellow-top" batteries. Optima offers up to twice the life of conventional wet lead acid batteries; this is important to me since battery removal/replacement is kind of a pain. Optima also boasts more than 15 times the vibration resistance of ordinary batteries…this is something for the off-road folks especially to think about. Finally, they’re spill-proof, which is a nice feature where the batteries share close quarters with other equipment.

I decided to use four of Optima’s group 31 batteries; at 75Ah each, this gives the battery bank a total capacity of 300Ah.

Rhino Linings’ liners are very thick and rubbery, which seemed perfect for a truck bed that would be hosting so much electrical power. The spray-in material also seems to provide some acoustic damping, which results in a noticeably quieter ride at highway speeds.
Sure Power Industries has been manufacturing high-quality isolators since 1959, providing models for a wide variety of applications. They also provide very responsive, friendly customer support and a handful of other fun products for large-scale truck applications.
To hold the batteries secure inside the tool box, I went with TH Marine’s plastic battery trays. They come in a variety of sizes and options, are made from thick, sturdy plastic and include a strap that is resistant to battery acid.

Final Thoughts…

Time it took to install:

Who knows? As with most of my projects, a lot of the time was spent in specification and design (my fancy terms for web browsing and saying "ooh…I want that!") The actual implementation went pretty quickly. I’d venture that I spent 20-30 mostly leisurely hours actually doing the installation. Of course, doing it a second time would be much faster.

Hardest part of the entire project:

Without question…picking up those batteries and placing them into their trays inside the box. I think I may have gotten a permanent tennis elbow in my right arm as a result of this.

The one thing I’d do differently:

Drilling those 1 3/8" holes for the conduit fittings. I am simply not strong enough to handle a heavy-duty drill running a bit of that size into metal. Since the conduit was a retrofit, I did the drilling for it with the box on the truck bed, which made it even more difficult. At one point during the drilling, the bit grabbed, and the torque wrested the drill out of my hands and down to the garage floor, taking a bite out of my truck’s paint along the way. At least neither the drill nor the bit was damaged.

The next time I need to drill a hole of this size in metal, I’m going to use a hole saw. From now on, bits that big go in the drill press, or they go unused.

The one tool I wish I’d had during the installation:

A heavy-duty wire stripper and crimper. I made do with my bench vise to crimp the terminals onto the wire, then dimpled them with a blunt punch and hammer, finishing them with solder. This whole process took a lot more time than it needed to. The proper tool would have sped things up significantly, and probably would have resulted in better crimps.
Possible upgrades to this installation: A few things come to mind. One is adding a remote on/off switch somewhere in the cab. This inverter accepts a remote line in through a connection I didn’t bother to show in the pictures. Another is running the inverter’s AC output to a second outlet, located outside of the tool box. Obviously, this extra outlet would have to be weather-resistant. With these two additions, it’d be possible to run the inverter without opening the tool box.

If I were to do this, I’d probably have to cut some ventilation holes in the box, and possibly add an exhaust fan. When the inverter is running near capacity, it and the batteries generate quite a bit of heat. If the inside of the box gets too hot, the inverter will shut down. With the top open, it’s very unlikely that it will ever get hot enough to pose a problem.

How much does it all cost? This turned out to be a pretty elaborate project, plus I went "big" with my components. Including all the components and bed liner, this installation represents about $3000 of goods and services. Before succumbing to sticker shock, though, bear in mind that there are many ways to trim this figure down:

  • reducing the number of batteries
  • using a smaller inverter or one without a battery charger
  • using a smaller tool box

It should be possible to implement a small-scale version of this project for about $1000. Whatever budget you choose, it will seem like a wise investment when you’re in the field and want….or need…AC power for something important.

The above tribulations notwithstanding, this project was an absolute pleasure…fun work and a very satisfying finished product. I’m sure I’ll never stop finding new uses for AC power on the road. I’m already looking for new toys to take into the field…you’ll see some of these in future articles!

As always, I welcome all comments and questions. These articles are intended to make seemingly-complex projects a little easier, so if I’ve goofed anywhere in this effort, I’d like to know about it. Thanks for reading!

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