Racers know moving weight to the rear of a vehicle is good for traction. By mounting the battery in the boot of a car, they are able to create more space in their engine bay and place the weight of the battery in a location that best suits their needs. Other types of vehicles that benefit from a battery relocation are four-wheel drive, trail-type vehicles. The battery is kept from being exposed to harsh elements found under the hood and allows easy access for portable winch use.
Park your vehicle on a flat surface. Turn the engine off. Open the bonnet and disconnect your vehicle’s battery by removing the positive and negative terminal connections with a wrench. Remove the battery and set it aside.
Decide on the new location for the battery. In most instances, the boot is the best and safest.
Mount the battery. Locate the battery box where you want it in the vehicle. Place a drill bit into the drill and drill through the battery box's mounting flange and into the vehicle's body. Drill an extra hole beside the battery box for the battery cable (wire) to run through. Using the mounting bolts that came with the battery box, place them through the mounting flange on the box and the holes you drilled and tighten all but one of them with a wrench. The final bolt will be tightened later.
Wire the battery. Using heavy gauge copper wire (12 gauge or better), run a piece of wire from the positive side of the battery through the hole you drilled in the floor of the vehicle and to the positive connection of the vehicle's starter. Use plastic zip ties to hold the wire into place along the frame, into the engine bay and out of the way of any moving parts. Using a wire stripper, remove just enough of the cable's protective plastic coating to allow you to crimp a terminal end to each end of the cable (wire). Attach one end to the positive terminal post of the starter and the other to the positive post of the battery. Run a small length of wire from the negative side of the new battery to the untightened mounting bolt of the battery box. Strip the end of the cable on each end and once again crimp on terminal connections with a crimping pliers. Attach one end of the cable to the mounting bolt for the battery box. Slide the bolt through the final mounting hole and tighten with a wrench. Attach the other end of the cable to the negative side of the battery. This will ground your battery to the vehicle's chassis.
When relocating a battery, it is best to purchase a relocation kit so you have all of the items you need to complete the project successfully.
Never allow a battery to sit in a boot without being mounted down. It could tip over and cause electrical shorts or a fire.