Well, I'd like to think the dealer would test the battery if I brought it in for electrical issues. I never had it tested afterwards. The volt meter is all over the place. Based on what I've read on GM's RVC system. It seems to function the "correct" way, besides the fact that sometimes I notice my voltage drop down to 11.9 when accelerating. (Sometimes it will go down to 11.8 when I come to stop, then go back up to 12.2-12.5 area after 5-10 seconds. (Stopped at a light or parking in to a space)
If I'm in 6th gear, going 70. The car sits around 14-14.5 volts. But If I'm in town, going 30-40 mph, sitting in 4th or 5th gear, the car varies wildly, some days it will be around 13-14 volts, but others it fluctuates between 11.8-13.
I've just never seen such wild fluctuations in voltage before in a car. I can drive a 370z and that sucker sits at 14.5 solid all day long. This car it can go up or down 3 volts in 2 seconds depending on acceleration or braking.