I drove down to Phoenix from Colorado yesterday without a hitch.

This morning I went to start my car and I noticed the Battery discharge light is on. It starts up fine and I drove it around for a few miles but I am heading back to Colorado tomorrow.

The battery is measuring 12.6. Volts. Are there any simple tests I can do? I don't really want to have to hunt around for a mechanic.

What should I do?

if your batt. light came on that means your not charging your battery so test the alternator, if its less than 13v while the car is running, measured at the battery then its time to replace it, also check the alt, fuse in the under hood fuse box