Battery relocations, I have questions

Updated: 09 Dec 2024

With an S14/S15 you normally have to drill a hole for aftermarket intercooler piping in the battery tray area, and because it’s technically an alteration to the chassis of a car fitted with airbags it can mean if it’s noticed in Australia your car can be taken off the road (it’s happened many times, some “not-so-kind” police know what to look for and take the opportunity to get a modified car off the road)

I’ve come up with a possible solution for my S15, by relocating the battery and washer bottle, grinding a bit off the bracket on the fender (under the bumper) and relocating a little bit of wiring, you should be able to modify a front-mount kit to run through a large hole next to the battery there from the factory. Meaning there’s no structural modification and you have a proper intercooler. I’ve seen pictures of a similar idea.

I just wanted some input on a battery relocation to the boot/trunk, there’s a lot of debate on the safety aspect of this. Some say you need a huge fuse, some say you don’t, some say the cost of the wiring makes it a bad idea, some say you’re asking for trouble by using that much cable to start a car. What do you guys have to say about battery relocations?

Comments

Here’s a photo showing the relevant area, the fender bracket is only visible from underneath. The hole is about 3 inches and to the left of the washer bottle

I’m a fan of battery relocation. It helps weight distribution and helps the battery last longer due to less heat from the engine. There are some good quality “relocation kits” online that are safe and easy to install.

If it won’t make your car illegal, go for it!

I agree with the weight distribution aspect, but honestly I’d be worried about a short from the positive cable starting a fire. I’ve seen the kits but I think I’d go DIY to make sure I’m not using too thin a cable, I don’t think 4 gauge would be ideal, I’d rather go 2. I like your thinking though, The S15 is nearly 50/50 and just moving the battery would make it bang on perfect I reckon

The R33 comes with the battery in the boot from factory. The only problem I found is that it is further to jump start. And it was really annoying just trying to take out or install the brackets when swapping the battery because you run the risk of accidentally hitting your elbow across the contacts. I don’t recall there being a fuse, but with longer wires you get a drop in current/voltage however it’s not noticeable as this length.

Yeah I’m already running a bigger battery than what it was made for because I have so much trouble with them, winter seems to kill every battery I buy so I’m not worried about the resistance from longer cables. Just the heat aspect of the resistance. Still, it wouldn’t be as annoying as owning an S15 that is no longer road-legal, I might need to have a look for R33 parts

I believe here in australia you can get away with a battery in the boot, but im fairly sure it needs to be a non spillable type that doesnt let off fumes that fill up your car while its charging, running a big fuse is advisable and will help prevent fire if something goes wrong, unlikely but best to prepare for the worst and hope for the best.

I think you can use a normal battery if it’s in a box and vented to the outside, but I’ll see what’s easiest at the time. Sounds like a fuse is a good idea