Percussive maintenance means to hit it
Get some new + and - terminals because they are cheap, clean off your posts with a wire brush or sandpaper, smear a little dielectric grease on the posts, and then spray this stuff on after tightening down your terminals:
http://www.usahardware.com/inet/shop.../crc/05046.htm
Various people make it, but it seals the terminal/post connection to keep the elements out. As a bonus, it makes great adhesive for the vented and solid shims used on factory brake pad sets
.