I did a voltage drop test on eight different areas on both the positive and negative side of the system. They were all under .5Volts with the highest being .11volts
The biggest culprit is probably the amount of time this truck sits. I have only been averaging about 2,000 miles a year on it.
The guy who I talked to about this issue and who helped me do these tests said that since my batteries are being subject to a low charge for lengthy periods of time because of the non use of the truck and it never has a chace to fully charge itself, it is killing the battery before it's time. He said most of today's battery's cannot hold up to that kind of use.
I have an O'reillys battery in my 92 Cavalier that is my daily driver, I have not had any battery issues with it so there is probably some truth to what he says.
I just had a Bosch battery go bad in less than 3 years in my 2004 Monte Carlo SS that sits most of the time. I bought it in Dec 09 and have only put 11,000 miles on it in that time. The Bosch battery had just been installed new right before I bought the car.
I have been driving the truck more often and will drive the Monte more often to try and alleviate this problem.
Wayne