I'm in the process of researching the forums regarding battery light issues, but I figured I'd post this in the meantime and see if I get any hits:
I have a 2000 6.8L F250. My battery light began to come on intermittently a few weeks ago. Once it was on it would stay on, but sometimes I would start the truck and it would be off, sometimes it would be on. Then one morning the truck would not start. I pulled the alternator and took it and my battery to the auto parts store - the alternator tested fine, but I had snapped a bolt while removing it and had to replace it anyway. The battery was totally dead, so I had them test and charge it.
The next three days the light never came on. Then the truck sat for a week while I was on vacation. The two days after that the light didn't come on. Then today it came on while driving in to work.
If there's a parasitic drain on the battery all the time, surely it would have drained the battery over the course of sitting for a week, right? Or does it depend on where the bare wire is?
I replaced a headlamp shortly before this all started - could it be possible there's a bare wire somewhere in the headlight circuit and the battery is only being drained when the lights are on?