I just bought repco 8 stage 8 amp one. Should have got one ages ago, works great, very happy with it.

Mines pretty much same scenario as you winnie, can be weeks between a decent drive plus i often work in the shed with the car radio going. Yeah i just leave it on most the time then cranks awsome when your ready to go. The redarc kicks in reasonably early so assume it's keeping that one toped up too.