Just scrapped a car for cash and have kept the battery. Have you or do you use a car battery for something other than your car?
Gonna get a Solar Panel Battery trickle charger and see what uses it can be put to. Up to now my imagination is only stretching as far as using it for the pond fountain, replacing the Mains.
Just be a nutter... life becomes much more exciting, and people won't expect anything more of you...