Originally Posted by mdefalco25
So my car has shown indications of a weak battery. Four years old, clock is not keeping up and if I turn car off after driving within a minute I get the low voltage warning and battery icon. I took car into dealer today to replace battery. They tested battery and said it came back strong and stated I have a parasitic drain. Dealer wants to do a parasitic drain test for two hours, but before I spend the money wanted to see if there was anything I could try or look into? Really am shocked it is not the battery and now worried it is something worse. Any advice is much appreciated!
For background, it is getting colder in IL and that's about when I noticed this happening and car is a 2008 E92 M3 with 41,000 miles.
UPDATE: 1/1/2013 picked up car today from dealer after battery was replaced. Car had been sitting in their shop for a couple of weeks waiting on new tires. Anyway, clock was set correctly and took car for a little spin. Parked it and put a battery tender on the car around 3:00 today. Four and a half hours later it still appears to be charging so guessing I have a parasitic drain. Guess it's back to the drawing board and figure out what is drawing power
Next time, go with a Sears battery. Depending on what kind of battery tender you have, it might take more than 4 hours. I have the smallest one available and it takes more than 12 hours to fully charge (only 1.5A). Let the car be, and see if the issue is gone.