JTB2000

My 2004 F-150 would not start yesterday. It had been starting just fine all day then it just quit on me. I checked the battery teminals and they were loose so after cleaning and tightening I got a jump start. All is well, right? Wrong! The charging indicator showed no charge from the alternator on my way home. I was just ten minutes from home and barely made it before the truck died.

So I charged the battery and got the truck running again. Took it to a parts store to be checked out and the alternator showed 13.5 amps output and the battery showed to be good. Then after restarting the engine the battery light came on so we did a re-check and the alternator output dropped to 12.5 amps. However the charge indicator shows close to a "normal" charge rate.

Now the battery light will come on and go off intermittently and eventually the battery dies and so does the engine. However, the charge indicator shows a "normal" charge rate for most of the ride.

Are these the signs of a dieing alternator? Why would this happen just like that? Or did I mess up something with the jump start?

Help!!