I've made a frame or or a large bracket, for the new aux battery and battery box. The battery is a Kings LiFePO4 120 Ah. I followed the Space X rapid prototyping method. I planned on having three cross bars and place the compressor in first. It was not possible to bolt in the bracket around the compressor with three cross bars or one or none. I did think of having a tray liner made out of ply, but ended up with just the metal.

Compressor.jpg
The compressor. I wanted to be able to remove in case or when fails.

Battery top.jpg
The battery in place

Battery 13.2V.jpg
Wired in with a Traxide SC80 battery isolator. The isolator must be 6 years old, or more.