My 96 f150 4.9L seems to have truoble charging the alernator seems fine and runs the truck fine when the battery is disconnected. their is a slight idle jump when i turn the lights on,but im guessing thats normal. When the truck is running and the battery is connected the gauge reads a little low but still between the little - + on the guage. When the battery is not connected it reads dead center. When the truck is off and the guage is reading the battery charge, it reads very low (The first 15-20 degrees). This is a new symptom but i have not been watching that closely and am a suspicious that it could have been happening gradually. the battery went dead about 6 months ago and i just assumed it was the battery. The truth is the battery they gave me at the dealership was tiny and i was in the middle of a job so i just baught a new one.(the biggest one canadien tire had.i Know Canadien tire,but it was close and i had no choice.)Now here i am with a battery that went dead on me last night after 2 hours of cruise control at 2200rpm.i got a jump and drove back lights off highrevin and hoping now it starts but still reads realy low when off. It held a charge,however low,overnight i have not run it at all today and i figure by tommorrow if it still starts its probably not a bleed or the battery.or at any rate a realy slow bleed. Please tell me how to truly eliminate these two possibilites (battery/power bleed). and list your most likely theories.my Knowledge is rudementary at best and i have no idea where to start.your replys would be greatly appreciated

Thanx
Deejay Greens

 

Have your battery and altenator tested to see which one is giving you the problem.