Update #29 - rear battery box and front motor mount #

2022-02-21

With a socket finally wired up in my garage for my welder, I’m getting stuck into making up the rear battery box. I’m making a frame out of 3mm x 30mm right angle steel. I then plan to line it with 1.5mm sheet. Don’t look too close at my terrible welding! This is the first thing I’ve ever welded.

The rear battery box will go in the space where the fuel tank used to sit. In this car, the fuel tank has a lip running around the outside edge. It sits down into a square opening in the chassis - the lip holding it up. The top of the fuel tank acts as the floor of some of the boot space.

At one point, I tried cutting the top off of the original fuel tank to try and re-use it. But it has rounded edges which make the usable space too small to fit all of my batteries.

So the plan is to make a square-edged tub which sits down into the opening in the chassis and has a lip like the original fuel tank.

I started at the top, making the lip part. I then welded on the four vertical pieces into the corners. The total height of the box will be 200mm, which is a little taller than the original fuel tank, but there is plenty of clearance back there. Before putting the bottom of the frame on, I tested the fit against all six modules on the bench. There is only around 30mm clearance in the width and length of the battery box, so I wanted to make sure I didn’t screw up the dimensions somehow.

There will also be plenty of space for cables to exit the battery box through the side/rear wall. I’ll need this in particular for the high voltage cables which will travel under the car to the high voltage junction box in the front.

Here is the frame in place - with two battery modules very carefully balanced. It fits very well.

I’m also working on the front motor mount. I’ve got a sheet of 6mm steel which I plan to use for this. I’m doing a little CAD (cardboard aided design) to figure out the dimensions for this plate.