[DonDavis]

Looks like overcharging. Don't touch a thing and get the system evaluated.

If that doesn't reveal anything, I'd remove the battery and thoroughly inspect all cable connections upstream and downstream looking for loose or badly corroded locations.
Keep in mind we cannot see inside the cable to determine if corrosion is creeping up the wires.

Do you have any aftermarket electronics? Lights, stereo, alarm?
One year, wow.

Aside from the mess, is everthing working ok?