I would check the voltage like mentioned earlier.

Just as a note. My Alternator has not gone out in my Mustang, but in my parents Ford Focus, it went out and the car couldn't start. Once it goes, the battery doesn't charge and it doesn't take long for a working car to drain a battery.

My alternator did go out in my 1980 corvette, but it was dying. An alert come from my dash and electronics acted weird. Replaced the alternator and everything back to normal.

Don't buy an alternator from Ford. They will charge you an arm and a leg. I know most people say buying alternators from parts stores is a bad idea, but I have never had a bad experience and neither has my father. We don't race, so that could be the difference.