I have a 2004 Chevy Silverado HD2500, Dual Battery Model. The original batteries are now exactly 4 years old. I had a dead battery this AM. Jump started OK and after a short drive things seem ok. Facts are:
1. Charge voltage is about 14.4
2. Battery voltage,12.6 after charge no load.
3. Both batteries show continuous 0.100 amp drain off and doors closed (measureing with ammeter with lifted ground cable.
4. Pulling fuses fails to reduce drain.
Help!
Did you allow all modules to time out (up to 2hrs)? Still this does not explain your new dead battery situation.
Battery voltage means nothing when you’re trying to start your vehicle. Amperage is what matters, and the only way to know your battery’s starting strength (Cold Cranking Amperage) is to have it “load tested.” Most parts stores and battery dealers will do this free.
Have the batteries and the charging system tested. My guess is one or both of your batteries are due for replacement.
What’s the point of two batteries if neither will start the vehicle?
Reason 1002 why you should never buy a GM product.
Some have found this article useful for finding the causes of battery drain: http://www.aa1car.com/library/battery_runs_down.htm