I had a 2002 Suburban that the battery kept dying on. I would drive it one day and the next day I would go out and the battery would be dead, the clock would flash 12:00 when i did start it. That suburban had battery problems from day one, and I purchased it new. I traded in the Suburban to get rid of the lemon. I purchased a 2007 Chevy Silverado 3/4 ton and it sits in the garage except when I tow something. I drove it on a Saturday with no problem and when I went out the next Friday to start it, the battery was dead. I did receive a phone call from the person who purchased the Suburban and they also had the battery die on them. I had replaced the battery with a brand new one that had a 5 year warranty in the Suburban the day before I decided to trade it in. What could cause electrical problems in multiple cars.
A simple test called a “Parasitic Load Test” will quickly find whatever is draining the battery in any vehicle.
Since the common factor is you, have you added any electrical equipment to the trucks after you bought them?
Also, never sell a vehicle to someone you know, for just this reason.
Easy way to track down a problem is to pull all the fuses in the panel, and hook up an amp meter between the battery terminal, and the negative battery cable. One by one place each fuse back in until you see a large drain on the amp meter.
That fuse is the one to track down.
BC.
Blade describes a parasitic load test…You can live with 200Ma, but even that will drain a battery after 10-14 days…500ma (half an amp) is unacceptable and will drain a battery in 2 days…The computers in most cars pull 100ma so expect that much even with all the fuses pulled out…If you get a big draw with the fuses out, the alternator is a likely suspect.