I have a 2004 Ford F150 and the battery keeps dying. We do not use the truck a lot and it sometimes sits outside for 2-4 weeks without being used. If it sits that long, it might be completely dead, but starts up easily with a jump and then works fine for a while. The battery is a 650 amp Motocraft w prorated replacement from 37-100 mo. The local Ford dealer has checked it several times in the past 2 yr and said it is fine, and that if the truck sits for a couple of weeks the battery will die. Is that right? I am not a car moron, nor am I an expert, but I am concerned that they are missing a small draw somewhere in the system. Should I be concerned about a draw or is this just something that happens to batteries as they get older? Thanks.

 

there could be a small draw somewhere that is running it down, but I have two different stories on two different trucks.......... first one did exactly what your taking about.. charge battery and its OK, 7 days later, not enough to crank. Battery was 4 years old. Replace it and problem solved...
------- second story, same problem for several months. One day the starter would not crank, jumped and still no crank.. bad starter. Changed starter and there was never a dead battery again... guess the starter had a very small drain.

 

I have a 2004 Lariat with 160,000 miles on it. Son has begun driving it as I replaced with a 2013 F150. Truck has subwoofer with amp under back seat. Same exact symptoms that you describe. Turned out to be a short in the amp for the subwoofer.