I've posted this on the Acadia Forum and there is quite a thread over there about the dead batteries and battery drain problems, but since I actually have a Saturn Outlook and not an Acadia, I thought I would post this here and see if anyone else is having the problem, or the answer.
I thought it was time to post another update, since I am still having the problem. I have noticed that my alternator recharges sporadically, sometimes only 12V and all the way to 14.9V (digital meter on the Pioneer Z2). I wouldn't think that the voltage regulator would ever let the voltage get that high. And sometimes it charges at that rate for only a few seconds and sometimes for half an hour.
Anyway, after my last trip to the dealer and their apparent lack of skill and experience in this area, it became painfully obvious that as long as I had the after market navigation system, even though it is connected to the factory power connections, they were going to blame that for the drain. So now, I have pulled the navigation system out, along with the rear seat DVD player.
Now the dealer has no excuse, except for their own inadequacies.
As someone else mentioned, the real pain here is the inconsistency. Sometimes, only 1 day and boom, no start......and sometimes it can sit for 3 or 4 days and no problem.
Another issue that I saw someone else mention.....the Battery Saver circuit. If that option works as it's supposed to, you should never have a battery that won't start the car. But that also seems inconsistent. Sometimes, I will get in the car and when it starts, the Battery Saver message is active and the A/C system is shut down. And sometimes, the battery is just too dead to start the car. Why didn't the Battery Saver "save" it?
One last little note. Someone else asked about using a voltmeter to monitor the drain. You would actually need an ammeter to monitor the current drain, but it's almost impossible for a "do it yourselfer" with all of the electronic circuits and computer modules on these vehicles. They do constantly draw some power and if a module "wakes up" then it can draw quite a bit, and if it keeps waking up and wakes up other modules in the process, you can actually have a substantial draw that would drain any battery....."IF" there weren't a Battery Saver circuit. (hence the reason they went to the extra expense to put that circuit in the first place). So this isn't like a car from the 60's when you could easily monitor a current draw at the battery terminal. You really have to depend on the dealer and their computer equipment. Just too bad that so many of them don't really know how to use the equipment that GM provides.