help. last summer i installed a new audio system. it ran fine until it was parked for the winter. only used the car a couple times this winter. battery seemed low. now it's dead. is my stereo system the problem, or is the battery just getting old? it's the original battery. my car is a 2010 sxt. the stereo system i had installed includes a new JVC head unit, a 1200w amp in the trunk and a 900w subwoofer. would appreciate any help. thanks.