As a matter of fact a battery can "appear" to be fully charged @ 12.6 volts yet have little or no reserve amperage.
Dead battery
Take out the battery and check if it's hearts still beating, if not call 911 immediately.
Sounds like you had crummy reception to the radio station you were listening to. I would have changed channels.
Here is how you can test your battery and you might want to test the alternator too!
How to test a car battery:
Sounds like the batt. is going dead
So I was looking at a few things in my neighbor's '94 Chevy Astro. I didn't have the engine on, I just had the battery running so I could listen to the radio. After just a few minutes, I noticed the radio was starting to studder, and go silent. Soon after, the dash lights began to go dim, and eventually turned off completely. I tried to start the car, but it wouldn't start. I figured it might be a dead battery, but then I noticed the headlights still seemed to be on fine. I really don't know much about cars, so I don't know if this is a battery problem, or a problem with a different component. What kind of problem does this sound like?
