I have a couple of dumb questions. Acquired my first truck two years ago, a 2005 Silverado Duramax. Runs like a champ aside from a persistent battery drain issue. Has an integrated trickle charger that may/may not be working. Recently left with dead batteries, so flat that the capacitor wouldn’t start the truck. Going to try using my external trickle charger to see if that charges it up and points to an issue with the installed charger.

I’m confused about some basic dumb stuff. Truck has two batteries (replaced both last spring). If I put my trickle charger on one battery, are both getting charged? Does having two mean that it’s 24 V?