To Steven M: Have a 2006 mustang,V6, base. Best car I've ever had. No problems. Bought it with 25,000 miles and now it has 108,000. Alternator was replaced a few years ago. A couple days ago, the battery was drained to the point that the car would not start. Happened overnight. When I jumped it, it started immediately. Would not hold a charge overnight. I checked the voltage from the negative side of battery to alternator casing while it was running and got 0.01 voltage. Have an alternator tester and it says normal at 14 volts. Let it run for 10 minutes after jumping it and checked the battery and got 12.85 volts. It will start on its own for a few hours but then drains while sitting overnight. Battery is an Interstate, 1 year old. Cleaned the terminals and see no signs of wiring problems. See no issues with loose alternator wiring. It seems pretty clean under the hood. Did I just get a lemon battery?
I know you were asking a specific user, but I'm just going to throw this out there--might not be your problem at all, but my 2006 GT Mustang had a problem with the battery from the time it was 6 months old. I bought it new, and the dealer replaced the factory battery at 6 months. Six months later, I replaced it with an Interstate. It always went dead if I didn't drive it every day (and I hardly ever drove it every day). It sits in the garage sometimes for a week. I finally replaced the Shaker 500 stereo system (mine died), and I've never had a problem with the battery again. I'd read that somehow the CD changer keeps searching for a CD even when the ignition is off (?). I replaced it with a Kenwood touchscreen with nav. Could be coincidence, but I'm convinced all of my battery issues were related to the Shaker 500. Not sure this could be your problem since it looks like your problem just cropped up. BTW, love my Mustang. She only has 21,000 miles.
Thanks for the reply. Come to find out, I was looking at the wrong battery receipt. The battery in question is actually 6 years old! So, it was the battery after all. Put a new battery in and it's fixes. Your answer is much appreciated. I will keep that info in my head for future solutions. Thanks, Dan
Looking for a Used Mustang in your area?
CarGurus has 43,893 nationwide Mustang listings starting at $2,000.
Search Ford Mustang Questions
Ford Mustang Experts