If test results for the battery is good, it may be the result of short trips and not being recharged sufficiently?
- be sure all interior lights are off when doors are shut.
- be sure doors are shut tight. I've realized a few times that a door was not shut and did not lock.
- lock the car. Do not know if it is the case for the Passport, electronics on some vehicles go into a sleep state to minimize power drain. There is always some power draw with modern vehicles and electronics.
- if you do not use your vehicle for extended periods of time, use a trickle charge to keep it topped off.
- worst case is a parasitic electrical drain, but not likely the case?