Re: Possessed? Could be..
Our local Autozone will test the alternator and battery (different tests) for free. I typically stop in once per year just to check, especially since I run original batteries on my roadster and '03 Audi A6. It may be worth checking your alternator to ensure it is making enough amperage when you are running radio, A/C or heater fan, rear window defroster, engine fan, etc. Heat is more an enemy of batteries than cold, so it also depends on where you live.