I just got my wagon's ignition tumbler fixed and the car had been sitting for about a month....Well it seems the battery isn't holding a charge anymore. After about 16hours its "almost" dead again.

I don't see any interior lights on or anything. The battery should still be under warranty as I bought it in 2007....but how can I be sure its the battery? I had no problems prior to it sitting for a month.

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2016 Monsoon Gray Audi Allroad - 21k
2008 Black Mercedes E350 4Matic Sport - 131k
2014 Jeep Wranger Unlimited Sahara - 62k
2003 Gray Mercedes ML350 - 122k