I just picked up a 98 Explorer XLT that had been sitting unused for about six months. I had to drive it from the SF bay area to Orange county, which is about a 400 mile drive. When I first started the vehicle, the alternator charging light was on and the voltage was definitely low (running on battery only).
I popped the hood, found a bird's nest under the hood and bird poop everywhere but nothing obviously wrong and no broken wires. I stuck the battery on a charger and prepared for an extremely unpleasant journey home on just the battery.
After about 15 minutes of driving, the charge light went out and everything seemed back to normal, voltage came back up. To me this sounds like one of two things:
1 - I'm a huge lucksack, or 2 - The voltage regulator is going bad on the alternator.
Could it be something caused from disuse (like bird droppings in some contacts)? Basically, is this something I should plan on replacing 100%? It's a Remy alternator that was changed out about six years ago.