Our most vulnerable one (and it's battery) is in a locked metal box which sits on an insulated post and is wired into the fence line - had it about 5 years now and so far, so good.
The fudger will probably be gone in the morning now I've said that
Nice one. How do YOU access the box...? Welding mitts?
Go a neighbour with a serious theft problem of fencers etc, I'll mention this one to him