After reading the blue book, which of course we ALL do… I found that I needed to make a washer ring to clamp the battery box down with. Basically, as the battery is a big old heavy thing, even crashing over the curbs could brake its mountings. Using a ring should help to maximise safety. Some battery boxes come with bonded in plates, but these were just too expensive for me, at about £200 so I decided to make my own. The first job for this was to cut a square plate to fit the box.
To get the edges straight and the correct length I stuck it in the mill. Unfortunately I dont have a pic of this.. I then placed the battery into the box and marked the mounting holes, these were placed such that the battery lies between the bolts. Next, as I want to keep the mass of the car down, and I think it looks better, I decided to cut out a square from the centre of the plate. So, firstly I drilled a hole with the holesaw in the centre. This is to allow the cutter to cut axially through the material as it cant actually drill like a normal drill. Next I roughly cut a piece of plywood to the same size as the plate, drilled the four mounting holes, and then counter bored the back holes, and mounted the plate to the wood.
I then slot milled the square from the centre of the plate. We do not have a CNC mill, but a square is not exactly complicated to do by hand!!!
After a bit of de burring I ended up with the final ring. I do not intend to bond this into the box, but i think it should be ok. Time I suppose will tell.
