Ok so winter started and I parked my e30 in the garage. I make sure I dont let it sit too long, I make sure I start and drive it every once in a awhile. Now ever since it started getting really cold up here in mn I come to try and start the car and the battery is dead. That was no big deal it was something I excpected because it was so cold and i havent started it for a while. So I jump start it and it runs fine. I made sure to drive it around too. The problem is now everytime i try and start it up either the battery is dead or most of the time the lights are VERY dim and the battery doesnt have enough juice to start (cranks a little bit the first try but very weak). This happens every time i try and start the car now.If i turn off the car and start it again right away then the car has enough juice to start but if i leave it off longer than like 10 15 mins I try and start the car and the lights will be REALLY dim and wont have enough juice to start. I know this is probably a simple answer but Im a noob so if anyone knows what it could be: Alternator, battery itself... I would realy appreaciate the help. THANKS!