What to use to keep battery charged while sitting?

hddecker wrote:

BarneyS wrote:
Get one of these battery boxes with built in solar charger. That way your batteries will be secure and still stay charged up. :)
Torklift website
Barney

Edit to add picture.

That's a nice box, at least it would keep the honest people honest. My luck I would come back to the rig and the batteries box and all would be gone.