Updated: Jun 24, 2019
This battery housing sits under the driver's seat. Unfortunately, I forgot to take a before photo. It's made of steel and was galvanised. However, the sides that were exposed to the elements had lost their galvanised finish. So, I wired brushed it and then sanded it down using a light grit paper ready for re-painting.
I primed the casing with a Halfords' vehicle spray primer and then top coated with Halfords Gloss Black spray paint. When I'm next spray painting I'll create a better paint booth as I found that dust was getting on to the wet paint.
Here's the finished battery housing. The nuts and bolts were soaked in Hammerite Rust Remover Dip and I put in new pop rivets with a manual rivet gun.