1. First of all, assess how you will run the wiring from the engine bay to the boot.
For me I had previously run 1ga from a grommet in the firewall to the rear of the vehicle. This was achieved by removing the seats and various panelling through the car to get the wire from front to back.
I removed the air box to ensure that I had enough room to shift and expose wiring where it was required.
There are 4 wires in total that have to be removed and relocated from the battery.
There are 2 wires connected to the positive battery terminal, the starter motor wire and the wire from the fuse box. There are also 2 wires connected to the negative terminal, the engine ground and the battery ground.
2. Remove the battery and associated brackets and grab your knife. Start removing the electrical tape that covers the wiring on the positive wires. Try not to cut the plastic split loom as well use it later to recover wiring.
This photo shows the start of removal of electrical tape and plastic split loom and identification and separation of wiring.
3. I started disassembling the fuse box. As you can see from this picture, I have exposed the wiring to the fuse box by removing the bottom cover.
4. After identifying the wiring to the starter motor, I removed the electrical tape to expose the wiring and the connection point for the wiring.
5. For my car, Toyota conveniently put a cover plug over the bolt that attaches the wiring to the starter motor. Grab appropriate socket and remove the bolt releasing the wire.
6. Just of note, I also located the engine ground wire and removed the wire as well.
7. I partially disassembled the fuse box to gain access to the fuse box wire. For me, this was just a plastic bracket that popped out.
8. I removed the wire from the fuse box that attached to the battery
9. I then prepared all my terminals and wiring terminations.
10. Grabbing some 4ga and I pressed and soldered a lug on and attached the lugged wire to the fuse box. The wire length is kept reasonably short to ensure that the wire is able to hold the electrical capacity and it connects to the distribution block that runs 1ga to the back of the car.
11. With the removal of the starter motor wire, I replaced this with 4ga as it is important that the wiring has the capacity for large amounts of current. Lugs were of similar size so I had no major problems with the upgraded wire.
12. With the replacement lugged 4ga, I mounted back on to the fuse box 12V connection point.
13. I cut a small hole in the base of the fuse box to run my new upgraded wire through and then popped the fuse bracket back into the fuse box. Then I replaced the fuse box base and reattached the top of the fuse box.
14. I re-attached the upgraded starter motor wire and put the plug back over.
15. Grabbing my electrical tape, I cleaned up and replaced the split loom where it was necessary to protect various wiring. I then attached the fuse box to another point to ensure that it was secure. I also replaced the air box voila, no more battery in the engine bay. In the future I plan to build a new air box and attach the fuse box to a more secure location than it is currently positioned.
Now my wiring is ready to go into the distribution block.
17. And all connected up.
Note:
With many people not having access to compression fittings and distro blocks this is what you do if you are rangi
don't forget to put heatshrink on before you attach lugs to wires :up:
- 17.1 lug up the other ends of the 2 x 4ga leads from the starter motor and the fusebox
- 17.2 put a lug on the 1/0ga
- 17.3 connect altogether with a nut and bolt, something that is large and will fit nicely in the 4ga lug hole
- 17.4 cover in heatshrink/electical tape. No metal to be exposed as it is constant 12V
18. With the removal of the engine ground which was terminated at the battery, I upgraded the engine ground and attached to a point on the body of the car. I found a mounting point, sanded back to bare metal and attached the engine ground wire.
19. Just as of note, the routing of the 1/0ga went through the inner guard. I first of all removed the inner guard plastic and found some nice brackets for me to attach my wire to. Thanks Toyota
20. You’ll have to use your imagination as I can’t be bothered taking off my wheel and documenting the actual wire in the brackets, but it was kinda fitted like this.
21. I also routed the 1/0ga through a grommet in the body of the car. The wire is fed through into the cabin and comes out to the side of the AC unit and down the kick.
22. To ensure that I protect the cable and don’t get any additional crap coming into the cabin, I carefully cut the old grommet to allow for the 1ga and replaced the grommet back into the hole with the 1/0ga fed through.
Replacing the inner guard, there is no evidence that there is wiring routed through the car and the wire is protected from debris that may fly up from the road. Nice and safe.
This step may change according to your boot and where the fuel tank is located.
For my car, the fuel tank is located underneath the boot floor and there is approximately 10 - 15mm to the top of the tank. I got Mr Kat to weld some bolts to the floor of the boot to ensure that I had solid mounting points for the battery and the future boot install.
For other cars, an alternative method may be to drill through the floor of the boot and attach the battery box to the floor of the boot. You can also use the side panels though in my car I found the metal to be rather flexible and unsuitable to mount to. Use a solid mounting plate underneath the battery to ensure that the battery remains stable at all times.
I then made up a solid bracket that attached to the welded bolts and added mounting points for the battery bracket rods.
23. I cut some holes into the rear of the battery box for the positive and negative wires and fed the wiring through. Grounding for the battery was located at a bolt hole on the rear factory strut brace. I sanded back and attached the ground wire and also fused the main 1/0 gauge power wire with my ANL fuse holder and a large 250A ANL fuse.
Note:
The engine starts off the battery initially and then the alternator provides constant current for the car. With the battery in the engine bay, the positive wire from the battery to the starter motor is short and can allow a large amount of current through its short lengh.
As we are increasing the distance between the battery and the starter motor, we must ensure that:
a) the cable can retain the current that is going through it
b) the fuse on the cable allows enough current through it to start the motor
c) the cable has a fuse on it to protect it
In this case, because we are relocating the battery in high powered car audio systems, it is always advisable to go a minimum of 2 guage power power, preferably 1/0 gauge. Going with a lower cable size may cause cable insulation failure to occur or a cable fault and cause a fire or accident.
The fuse should also be securely mounted and protected and should be a rating of at least 150A. This is to allow adequate car starting and allow continual current draw.
Drilling some holes into the base of the battery box, I threaded the battery bracket rods through the box and fed the positive and negative cables into the battery box. I then attached my battery terminals.
24. I then mounted the battery inside the battery box and connected the terminals. I then used the brace to hold the battery in place to ensure that the battery is secured down.
25. I then put the cover on and one battery relocation finished.
(Don’t mind the extra cable. It’s there for my future setup though I have to add some more RCA’s and more speaker wire as well as the power wiring to the front).
Tutorial and all associated pictures are property of David Choong. Rights Reserved.