My GT usually reports the battery voltage around 11.7-11.9 when the car is off. I've always expected a new, fully charged battery, to report closer to 12.5 or more when it's fully charged. Had Ford check it out to be sure, because my 05's battery died on me within the first year. They said it's normal, and I'm inclined to believe them since I haven't had any starting issues, but was wondering if you guys are getting the same results from your Mustangs?