When I bought my 03 Chevy I would not drive it for weeks at a time. When I would go to drive it the battery was dead
...our 2004.5 Silverado 2500HD OFTEN sits for 1 or 2 months after we reconstitute it from winter storage, with absolutely no issue whatsoever vis starting (no battery minder connected, and the batteries never disconnected). We've been doing this since September 2004-- almost 10 years. Our truck batteries are OEM factory, and are just about as strong today, as the day we bought the truck. I did use a battery minder one winter over the past 10 years of storage, however, the other 9 years, no supplemental trickle charge at all.
I would say that perhaps rust has played havoc with your electrical system over the years? I rust-proof every square centimeter our truck chassis (both undercoating and the engine compartment, and every linear centimeter of brake line)) twice a year, right from the hour we took delivery from the showroom new almost 10 years ago. I wouldn't replace this 10 year old Silverado even if I was given a brand new one free from GM (I go on record here with this statement).
