Why does ford expedition battery drain
The most common is a failed diode in the alternator, but try this: grab your 12 volt test light and disconnect 1 battery cable, put the test light in the between the cable and battery post, with everything shut off and the doors closed there should be no light, note there might be a slight glow but that is normal, if there is no light then you have a bad battery, if there is a light then electrically disconnect the alternator, if the light goes out then you have found your problem, if not then proceed with removing the fuses one at a time noting where each fuse was until the light goes out, once you have found what circuit has the draw then you need to find out what component is causing the draw on that circuit and repair or replace it, then start putting the fuses one at a time watching the light, if it stays off then your good to go if not repeat the above. HTH
If you don't want to do this yourself, and you're a member of AAA, give them a call. They have a battery service for their members at no charge and will come check out your charging system. They also sell great batteries with a 3 year unconditional guarantee, very good service.
Search Ford Expedition Questions
Ford Expedition Experts
Related Models For Sale
Used Cars For Sale