Connecting trickle charger direct to fuse box

[tejr]

I think the Ctek is rated at 3.6A max and there seem to be 2 permanent live inputs on the fuse box in the boot. Any reason I can't take this easy option and wire direct to there? If so, wheres the best place for an earthing point?

[Tanguero]

There is an earth point behind the boxes above the fuel tank in the boot.