What’s there to it??
Interested in relocating your NC’s battery into your boot? I’m going to make this guide extremely simple yet give you everything to do a proper job. Now relocating your battery as an overall idea sounds incredibly simple right? What’s there to mess up? There’s quite a few things you’ll need to do and take into account when relocating your battery from the engine-bay to the rear of your vehicle. Before we start, I’d like to mention there is only one downside when doing this. That’s, your chosen battery will now be taking up space in your boot. If you’re happy that you can live with that, then let’s get started.
Choosing your battery and mounting hardware
Let’s start at the heart of your car’s electrical system, the battery. Whenever mounting a battery outside the engine compartment, it should always be a sealed AGM type battery. Period. Why’s this incredibly important? Two reasons, first let’s say the worst thing happens… Your in a wreck, the vehicle’s upside down. If you were to re-use the original battery you’ll find mounted under the bonnet, you’re quite likely to have hydrochloric acid leaking out everywhere. Terrible situation. The second reason is an AGM dry-cell battery does not need any venting. A regular car battery will have a tube that is used to vent away hydrogen gas as your battery charges. So to avoid both of them issues we use a dry-cell sealed AGM type battery that can be mounted in the passenger compartment and can also be mounted any orientation, no problem.
What options are on the market then for this? There are many options, entirely dependent on what you want and how you intend to use the car. Names that are popular are Oddessy, Dead-weight batteries, Optima, Yausa. In this part, I thoroughly encourage you to do your research and see what will suit your requirements as a battery. Now, once you’ve decided on a battery, you’ll need to find the appropriate hardware to mount it securely in the boot of your vehicle. You will find enclosures like mine, which is a Motamec standard size battery cage. However, if you intend to use the Oddessy style, say PC680 they and many other companies sell an enclosure suited to that batteries dimensions. Again, this is something for you to decide. But what is not up to you is you need to use M8 grade 8.8 steel bolts at a minimum, in my case I used four M8 bolts to secure it to the boot floor. Now in the event of hard driving or an accident the battery is thoroughly secured and not going to become loose and become a flying projectile.
Components and diagrams.
All I’m about to mention is suited for the NC chassis. So what cable will you need? What you’ll want is 40mm2 oxygen free copper (or ofc) welding cable. I purchased 5 metres that would allow enough length either end. In addition extra length to make a short little ground-cable from the battery to a suitable chassis-ground. There are many ways to wire a racecar. But this is the simplest way to do so on this platform.
To simplify this article even further, I have created a diagram below that explains the setup in my personal car. So let’s start from left to right. The first location is the boot. In the boot we have the main vehicle battery that has one short ground-cable from the negative battery terminal to a suitable chassis ground. On the NC that location is one of the bolts near the fuel filler protective metal cover. A small portion of paint is removed. Just enough to still be covered by the crimp-lug. But this will allow a much better ground path and not rely solely on the zinc-plated bolt. By providing an increased surface area.
Working away from the positive battery terminal, we make the first stop at the power-distribution box. This neat little box is configured in the image attached below. As the positive path enters the power-distribution box it splits. One path runs through a 200amp Megafuse and the other is used for future circuits that are NOT related to this battery relocation. As we carry on we leave the power-distribution box and head onwards to the front of the car. Routed past the rear shock tower and along the passenger side and sill oem wiring. We then leave the passenger compartment and penetrate through the firewall into the engine bay.
Once we get through the firewall and under the bonnet via a small hole in the bottom section of the oem firewall grommet we connect to a 3way power-distribution joint box. The starter motor/alternator leg which is a 25mm2 cable has a crimp lug attached and connected to the joint box. The last leg is a new leg. This leg replaces the fusebox main supply. This new leg is a 16mm2 supply. I actually ended up up-rating this leg as I couldn’t determine it’s original size. From the joint box we have a 16mm2 crimp-lug that goes direct to an inline Midifuse (with a 125amp Midifuse) (please see pictures to best understand). Then from there alongside the oem wiring loom under the bonnet. Then turns off near the main fusebox and goes to a 90 degree 16-6 crimp lug. Then attaches to the oem connection point.
Complete list of parts and associated links
Listed below are the parts you’ll need to complete the job and replicate exactly how I’ve done this on my personal vehicle.
- A suitable AGM battery.
- A suitable battery enclosure.
- 5 Metres of red 40mm2 ofc welding cable.
- 1 Metre of black 40mm2 ofc welding cable.
- 5 Metres of plastic conduit non-split (16.9mm I.D.). [To protect main battery cable through vehicle].
- x Metres of plastic conduit non-split (x I.D.)
- MTA power-distribution box.
- 200amp Megafuse.
- Suitable crimper that has 50mm2 crimp dies.
- 6x 50-8 crimp-lugs.
- 1x 25mm through-crimp. [For starter motor cable join with more 25mm2 battery cable to reach joint box location].
- 1x 25-8 crimp-lug.
- 1x 16-8 crimp-lug.
- 1x 16-8 90 degree crimp-lug [For connection to oem connection post inside main fusebox under bonnet].
- Midi inline fuse holder.
- 2x 16-6 crimp-lugs. [To splice in inline-fuse between joint box leg and main fusebox connection, situated straight after joint box. Please see article photos above for visual reference].
Links to the parts I used below.
Battery – https://www.thebatteryshop.co.uk/yuasa-12v-60ah-680a-agm-stop-start-plus-battery-ybx9027-027agm-8897-p.asp
Battery enclosure – https://www.ebay.co.uk/itm/293522179394
Cable – https://www.ebay.co.uk/itm/201701872149?var=501498662334
Plastic conduit – https://www.ebay.co.uk/itm/133103616650?hash=item1efd98028a:g:SdgAAOSwzFRdG8~m
Heatshrink – https://www.ebay.co.uk/itm/203043868181?var=503258456813
200Amp Megafuse – https://www.ebay.co.uk/itm/121208867237
Cable Crimper –https://www.amazon.co.uk/gp/product/B07D5LFB55/ref=ppx_yo_dt_b_asin_title_o01_s00?ie=UTF8&psc=1
Through-crimp – https://www.ebay.co.uk/itm/122409542148?var=422882163682
Crimp lugs – https://www.ebay.co.uk/itm/223200585987?var=522000906826
HPDE sheet – https://www.ebay.co.uk/itm/171947858233?var=470846430087