The proper NC MX-5 battery relocation guide
Hold your horses!
Before we can get into the steps, you’ll need to complete your installation you need to step back and understand the system before installation. This will cut down the install time for you and should give you a better understanding of why and how the system works. So should any problems occur during the installation or in the future you’re fully equipped to diagnose it.
The diagram below summarises the entire setup. This setup is identical to my car. Working away from the positive battery terminal. We make the first stop at the power distribution box. This neat little box is configured as in the image attached below. As the positive path enters the power-distribution box it splits. One path runs through a 200A mega fuse, and the other path is used for additional circuits that are not related to this battery relocation. As we continue, we leave the power distribution box and head onward to the front of the car. Once we get through the firewall we connect to a three-way power-distribution joint box. The starter motor/alternator leg, a 25mm2 high-flex cable, has a crimp lug attached and connected to the joint box. The last leg is new. This leg replaces the fuse box main supply. This new leg is a 16mm2 high-flex supply. I uprated this leg as I couldn’t clearly determine its original size. From the joint box, we have a 16mm2 crimp-lug that goes directly to an inline midi fuse (with a 125amp midi fuse) (please see pictures to best understand). Then from there alongside the oem wiring loom under the bonnet. Then turns off near the main fuse box and goes to a 90-degree 16-6 crimp lug. Then attaches to the OEM connection point.
The original engine ground is simply replaced with a tinned-braided ground cable from its original bracket on the engine to the original cross-member grounding point. Which coincidentally has a ground symbol beside the M6x1.0mm female thread.
Now we’ve covered the circuit design. Head to page three using the navigation directly below for the install guide.