[Joe Bob]

Yeah...prolly the alternator. But it sounds like you used the battery charger to JUST start it. You should have FULLY charged it.....even with a GOOD alternator....it will put strain on the alt trying to bring up the battery.

Alts are NOT designed as battery chargers...they are battery maintainers....

If you had charged the battery fully, it would have run fine for many hours without the headlights on....I had a dead alt and made it back from AZ to the coast of CA on battery power...