I am working on a 94 F150 that drags the battery down, especially when it is running.
My friend was just cruising around when all of a sudden the truck started acting up (running rough, hesitating, etc.). She parked and then the truck wouldn't start. The next morning we returned to the truck and it started. However, on the trip home (about 4 miles) it started acting up again.
I checked the battery and it was at about 9 volts. Tried charging the battery and it only charged to 11.4 volts after a full day.
A fully charged, supposedly good battery, was installed. The truck started fine. I checked the voltage at the battery with the truck running and it was 14.5 Volts. Overnight, the battery ran down again. Obviouly something is draining the battery.
I recharged the battery and took a short trip to the store. A trip of about 30 minutes discharged the battery down to 9 volts. Of course the truck doesn't run very well when this happens.
When I recharged this battery it only charges to 11V.
My biggest fear is that something is eating batteries. The only thing I think would do that is if the alternator is overcharging them.
Has anyone had this problem or have any other ideas?