I just got back from a long trip (5K). When I returned I cleaned the car up, changed the oil and filters (air filter was filthy). I crawled around under the car to check if all was ok, it appeared to be. Checked all the lug nuts, but I did not to think to check the tightness of the battery terminals, my mistake.
All I can figure is that there was a lot of bouncing around of the car on the trip and the nut on one of the battery terminals worked loose, it did not come off, but it was a loose connection. For those of you that dont know (that was me, until this happened), if you have loose battery terminal connection when the car is running it cooks your alternator almost immediately.
I started the car and the red electrical indicator on the dash came on, by the time the car was shut off, the alternator was toast. Rebuilt alternators are over 400.00, ouch....
Ed