I agree with nuke, the first thing you need to do is check for cracks. If you don't find any though I would reccomend you purchase battery terminal washers (the $2 felt ones) and some battery terminal spray. I have had corrosion issues on a few older vehicles before so I started using these things and they help tremendously. I now put a set of the washers and spray on every vehicle I own. If that doesn't help then you definitely have a bigger issue.
'07 4.0 Coupe, 5spd mt, Tungsten Grey;
true duals w/ H-pipe and GT takeoffs, Tunable Induction CAI, BAMA custom tunes;