Battery going dead

The battery in my 86 Lincoln S&S goes dead in a week if I dont drive it. The battery is only a year old and is the proper size & CCA for the car. I have had the battery tested with a load test and a hydrometer and it tests good. The alternator on the car is charging and its a 100 amp alternator. Ive checked for a drain on the system and all I find is the factory clock, but that shouldnt drain the battery in a week. Besides installing a battery shut off switch, any suggestions?

I have a 13 avalanche doing the same thing. but one thing to test is stop light switch or the door jam switches. they would be about the only thing on that one hot with the key out. sneak up on it in the dark and see if maybe there isn't a glow on one of the bulbs. in that length of time it can't be bright.

Put a master cutoff switch on it. I have one on all my (old) cars. I don't want to wake up at 2 am and see my whole shop on fire!!

I have battery cut off switches on all my cars because I have had a car fire, and don't desire to relive that. But in direct answer to your question Rick, try replacing the starter solenoid. Being located right on the inner fender, its an easy five minute swap, and as I recall costs less then $20. My mother had two 1987 TownCars, and both would develop mysterious battery drains after awhile. The starter solenoid became my go-to fix when nothing else seemed to be the cause. Just be sure to disconnect the battery before swapping the solenoid, and yes, that's the voice of experience!

Concerning battery disconnect switches, I am very much an advocate for them, especially after having a car fire, but they are not perpetual. After a few years they develop enough corrosion to impede with starting the car and impede the alternator from properly recharging the battery. This is NOT meant to say don't use one, I'm simply saying that if you install one and after a few years your car isn't starting or charging like it should, check the disconnect switch.

look at night

Check the car with a charged battery at night. A friend had a car that went dead often and in a short time. He went out in the driveway late one night and there was light coming from under the car. The under hood light was not shutting off when the hood was closed.
Just one more thing to check.
good luck,
Mike

each of the cars has there little miss steps. the solenoid makes sense but I have not experienced that problem. the walk around and look for the glow in the dark is the one trick I have found that does it. fords security system on the later cars was a drain on a sitter also. but the old boys would just unhook the pos cable each time. never have it tight so they could just twist it off. funny you would think at least once they would get in trouble with it falling off but it did not seam to ever happen.