Adding 120V AC Power To a Truck Bed (Part 2)

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Installation ­ The Preparatory Work

The project truck.Here’s the beast that’s ready for the addition, a 2001 Ford F-150 Super Crew 4×4 with a 5.4L engine. Though it’s a 4×4 and does at times venture off the pavement, this vehicle rarely does any hard-core rock shredding or mud-whomping. I consider my installation to be fairly robust, but if your vehicle is going to experience extreme usage of any kind, you may want to consider beefing up some areas of my installation to suit your usage profile.

As this project entails working with heavy components, tight spaces and dangerously large amounts of electrical power, it seemed like a good idea to carefully plan the installation. I decided to tackle the project in this order:

  • installing the isolator under the hood
  • running the wiring from the engine to the bed
  • preparing the box for component installation
  • putting the box onto the bed
  • installing the components into the box
  • hooking up the wiring in the box

First…Preparing The Truck Bed

When I first planned this project, I intended to install the tool box onto my OEM plastic bed liner. When I test-fit the box, however, I discovered that the rounded corners of the bed liner prevented the tool box from fitting flush against the back of the bed. I could have merely cut holes in the corners of the bed liner, but I then remembered hearing bad things about how drop-in liners are tough on the bed and can lead to rusting, so I decided to remove the liner for an inspection.

It is clear that the drop-in liners’ reputation for being hard on the bed’s finish is deserved; the paint on several high points of my bed had been worn though to the primer, as this photo shows. Similar wear was also found on the wheel wells and tailgate. It was easy to see that this could lead to rust if not remedied.

I’d had good experiences with Rhino Linings spray-in bed liners, so I decided to go with them for this project. After discussing colors with Mike Benedetti of A-1 Rhino Linings in Colma, CA, we decided on the graphite gray. Once installed, I was thrilled with this color selection, as it nearly perfectly matches the window trim on the truck. In addition to being a much better bed protector than the plastic liner, it is much more attractive. I also noticed that the truck seems to be quieter on the highway…perhaps the Rhino liner performs as a sound dampener as well.

Just for fun, I also had Mike spray the inside of the tool box. Even though all the equipment I’m planning for this project is going to be bolted down, it’s still nice to have a grippy, rubberized surface to hold in place anything else I might throw in the box.

I also had Mike spray the underside of the tool tray that comes with the box, in case it came into contact with any of the wiring in the box.

Under the Hood

the mounted isolatorThe first component I installed was the battery isolator. The only really difficult part of this step was finding a place for it. The isolator should be mounted near the alternator, and not too close to a major source of heat (like the exhaust manifolds). The best (and almost the only!) place I found was here behind the intake shroud.

Because I mounted the isolator vertically, I decided to drill some holes in the mounting flange. Using these holes instead of the pre-cut slots means that the isolator will still be somewhat secure if the screws were to vibrate a little loose.

I used two screws to secure the isolator…perhaps not bullet-proof, but adequate for my purposes. If I felt that it needed to be more secure, I’d fabricate a mounting plate, but it’s clear to me that this isolator isn’t going anywhere.

Even though I used a center-punch to create a dimple for guiding the drill bit, the drill still "walked" a little on me. This is why the isolator is a bit crooked. I won’t tell if you don’t…

the isolator with wiring connectedHere’s a picture of the isolator with the wiring connected. (It’s all hidden behind the protective split loom, but trust me, it’s in there.) The cable marked with the yellow "A" runs from the alternator. I was able to re-use this cable because I’d (luckily) mounted the isolator close to the alternator. You may want to keep this in mind when choosing your mounting location for the isolator. The end now connected to the isolator originally went to where the left end of cable "1" now connects; this is a battery connection point.

Cables "1", "2" and "N" are new cables that I installed with the isolator. Cable "1" connects the starter battery to the isolator.Cable "2" disappears down the engine compartment and heads for the rear of the truck, as does cable "N" (the neutral cable return). The extra stud on the isolator is called "E" (for "Exciter") in the Sure Power instructions. Some vehicles require that this be connected to ignition power; mine did not.

Running (and protecting) the Wires

It was now time to run the electrical cables (installed above) from the engine compartment to the bed of the truck. I actually did this step twice during this project. Originally, my plan was simply to clamp the wires to the frame rail using a metal bracket with a rubber cushion (shown at left). Once this was in place, though, I began to have second thoughts, imagining all the things that could grab at the wires when the truck is off-road, and decided that a more robust form of protection was in order.
After an online review of the alternatives, I decided to go with flexible conduit. The conduit I selected is all Nylon, liquid-tight, and has a high degree of structural integrity (meaning it doesn’t bend or break easily) while being very flexible. This was important given some of the angles the conduit had to follow in the installation.

The conduit is held by clamps that feature a "rib" running around the inside circumference. This rib mates with one of the grooves in the conduit to ensure that the conduit doesn’t slide in the clamp. The end result is a very positive fastening. Here’s a picture of a clamp fastened to the frame rail. I used #14 Tec screws after drilling #7 pilot holes.

Here’s a picture of the conduit in one of the clamps, with the clamp cover snapped on. (All those other holes in the frame rail were already there, and are not my failed attempts at installing the clamp!) The clamps keep the conduit tightly hugging the rail, to minimize the chances of a bush or rock grabbing it and tearing it loose.

Another view of the conduit running along the frame rail (taken before the clamp covers were installed). I felt that it was important to keep the conduit as high and as close to the frame rail as possible; fortunately, the clamps I used did this very nicely.
When the conduit got to the point in the frame where the cab meets the bed, it was time to "go vertical." This picture is looking (nearly) straight up into the gap between the cab (on the right) and the bed (on the left). Though you can’t really see it very well here, the conduit is running through the access hole in the forward wall of the bed.

It was at this point in the installation that I became very happy that I went with 1" Inside-Diameter (ID) conduit instead of something larger. While this conduit may look like split-loom wiring cover in the pictures, in real life it is considerably stronger, despite its very light weight. To get the conduit to pass through the access hole in the bed, it was necessary to flatten the cross-section slightly (which was not easy to do). Fortunately, since I’d used 1" conduit, it was only necessary to flatten it a little bit; anything larger would have been considerably more difficult.

A final note about running the cables: I found it much easier to run the cables through the conduit, then mount the conduits to the brackets. This was mostly due to the very stiff sheathing of my cables, but I have to think that this is the preferred way to do it in most cases.

I was very happy with my retrospective decision to install wiring conduit; it didn’t take much extra time and it makes me feel much better about the robustness of the installation.

Preparing the Box for Installation

By "preparing the box" I am referring to drilling all the holes necessary for installing the components and installing any mounting hardware. Do not, I repeat, do NOT, underestimate the planning necessary for this step, or it will eat your lunch. I’ve often been accused of using a "measure with a micrometer, mark with chalk, cut with an axe" methodology, but in this case, I was even more careful to make sure that I got everything in the right place. I felt bad enough defiling this pristine tool box with a drill bit; had I drilled holes in the wrong places, I’d have felt as though I’d just painted a mustache on the Mona Lisa.

I decided to work from the outside, which means I had to turn the box upside-down and "flip" my floor plan for the components. The alternative is to unscrew the top (lots of screws) and even then, I didn’t like the prospect of horsing around a drill inside the box; these boxes are a lot smaller on the inside than they are on the outside.

The first thing I did once the box was flipped was to draw a large cross in the middle of it with a Sharpie, to help me center things and to use as a reference point. I then laid out all of my components on top to make a final check of the fit (I’d already done this on paper when selecting my components). Once I was quite certain my floor plan was truly viable, I used the Sharpie to mark the points where I’d drill.

After marking the places for the holes, I used a spring-loaded center punch to give me a little dimple in the very center of each hole-mark, to help keep the drill from walking on me like it did in the engine compartment. You really can’t be too careful in getting these holes right. After dimpling, I took a deep breath and drilled the holes.

I did a similar exercise on the face of the box that would hold the fuse blocks and allow entry to the electrical wires. For the latter, I needed a 7/8" hole. (Note: when I decided to retrofit the conduit, the hole size increased to a whopping 1 3/8".) I borrowed the drill bit from some friends at the Billy Jones Wildcat Railroad. To this point, I’d drilled all the holes with my 14.4V cordless drill/driver, but for holes of this size, it was clear that I’d need something with a little more oomph, so I pulled my 1/2" corded drill off the wall.

When drilling holes this big, it helps to begin with a pilot hole. Even so, the drill tends to chatter and try to move around a lot. It’s important to resist the urge to fight back by pushing harder onto the drill. When the bit finally breaks through the aluminum wall, it may catch, and the inertia in the drill’s motor will jerk the drill sharply enough to wrest it from your hands. I wouldn’t be surprised if people have sprained their wrists from this. You can minimize the chance of this happening by keeping a light pressure on the drill at all times, or, as my dad used to say, "let the tool do the work."

After drilling all the holes, I cleaned off any burrs with a hand file. For the biggest holes, I attached a conical grinder bit to my cordless drill/driver and hit them lightly to remove any sharp edges.

After all the holes were drilled, I flipped the tool box back to right-side-up and installed the battery trays and the fuse blocks. I inserted the screws in from the bottom, so that the underside of the box would be as smooth as possible (making it friendlier to anything with which it might happen to share the truck bed).

It was easier to work on the box when it was on the floor of my garage, but with everything in the box, it weighs over 400 lbs. and would have been tough to lift into position. So, I installed as much into the box as I could while still keeping the box light enough to pick up and maneuver into the bed. Once the lightweight stuff is in, I then situated the box in the truck bed, then put the heavy stuff in. If you can get a few people to help you pick up the box, you can consider putting everything in before lifting the box onto the bed, but I’d really recommend against it.

Now that all the preliminary work is done, it’s time to put the tool box on the bed and install the fun stuff.
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