Moving battery to boot.

Iamzod

Iamzod

Iamzod

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I'm looking at moving the battery to the boot on one of my cars, however I am no electrician & obviously I don't wish to cause an electrical fire so I thought i'd ask some advice. I am running the positive cable under the car rather than through it if that matters at all.

There are a few things that have me stumped-

Should I run a negative under the car also or am I going to be fine earthing the battery to the shell of the car?

How do I work out what thickness cable I need?

I know I will be needing a fuse of some sort, again how do I work out what rating I need?
 
Well, in all the cars I've owned with a factory-fit boot-mounted battery, they were all simply connected to the car for the -ve terminal. Additional -ve terminals were under the bonnet in isolated boxes. +ve obviously needs running from the boot to the front, I'd also mount yourself a "jump" terminal under the bonnet in-case you need it for diagnostics and the like.

As for gauge of wire, not sure, but there's no such thing as too thick :) To hazard a guess though, 4 gauge (4awg) at a minimum.
 
I had to add a couple of extra earths off the engine last time I ran the battery in the boot as it caused me slow starter issues!
 
As has been said, thick cable, 0 or 2 AWG would be best really and a secure mounting point in the boot and it'll be fine. You will probably want to get a battery with as high as possible CCA as you will have power drop on start up compared to the front so don't want to overload the cable.
I'd also suggest installing a circuit breaker by the battery so if the worst happens (+ve cable melts / chafes / grounds) then it'll stop anything bad from happening, they are cheap enough and can just be reset, unlike a fuse.

With an older low CCA battery I kept tripping mine as the draw was increased when cranking to try and get enough power to start.
 
Iamzod said:
I'm looking at moving the battery to the boot on one of my cars, however I am no electrician & obviously I don't wish to cause an electrical fire so I thought i'd ask some advice. I am running the positive cable under the car rather than through it if that matters at all.

There are a few things that have me stumped-

Should I run a negative under the car also or am I going to be fine earthing the battery to the shell of the car?

How do I work out what thickness cable I need?

I know I will be needing a fuse of some sort, again how do I work out what rating I need?
Click to expand...
you can earth to a bolt in the boot and run a length of of cable from positive to the fuse box, alternator and starter. Use the same gauge cable and don't run it under the car, you don't want to damage the cable and cuase a short.
 
red eye said:
you can earth to a bolt in the boot and run a length of of cable from positive to the fuse box, alternator and starter. Use the same gauge cable and don't run it under the car, you don't want to damage the cable and cuase a short.
Click to expand...

I was going to run it with the brake line down the transmission tunnel. If it shorts it should blow the fuse/circuit breaker. I don't want it anywhere near upholstery that burns.

It is proving difficult to find wire offline.
 
Any local motor factors will have wire of the right gauge surely?

I could walk into a number of shops round here and get 2AWG wire.
 
I did this in the Evo as when fitting an intercooler hard pipe kit, it fouls on the stock battery tray. This meant you either had to fit a smaller battery - which was what was in place when I bought the car - however, the battery would only last a week in cold weather, and I wasn't driving the car much at the time.

I ran the cable through a bulkhead grommet and down the side of the car under the kick plates. It comes out of the void near the near-side rear cluster. I've also placed a fuse in the cable just before it comes out of the void.

The battery is a beefier, nearly leisure grade battery and sits in a plastic battery box which is riveted to the boot floor. The battery is secured using a strap. The negative runs to the boot floor to bare metal.

All my materials were sourced from here:

http://www.autoelectricsupplies.co.uk/category/24
 
As above, I found a good small battery for my Galant, it wasn't cheap but it was tiny and did keep a charge for good time. Might be worth doing to avoid hassle if a small battery fits
 
Managed to find cable at a welding supplies place a mile from work, only £3 a meter too for 40mm2 which is a tiny bit thinner than 1AWG from what I can tell.

:D
 
Iamzod said:
I was going to run it with the brake line down the transmission tunnel. If it shorts it should blow the fuse/circuit breaker. I don't want it anywhere near upholstery that burns.

It is proving difficult to find wire offline.
Click to expand...
You would need something like a 200-250 amp fuse at the battery for the starter motor regardless of where you run the cable. What car is it? I think vag cars have the fuse on top of the battery, you could find one in the scrappy and use that.
 
red eye said:
You would need something like a 200-250 amp fuse at the battery for the starter motor regardless of where you run the cable. What car is it? I think vag cars have the fuse on top of the battery, you could find one in the scrappy and use that.
Click to expand...

It's a Ford Capri. I have found various automotive circuit breakers online, they aren't expensive so will get one of those.
 
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