Get the car out to @ smiffy for a good look over. I'd be looking at an over active alternator which can kill a brand new battery in very little time and render it unchargecable. Had that exact problem in my Jeep! Killed a new battery during a 2,000 mile trip. Fortunetly checked the output of the alternator and it was fluctuating over what out put should have been. Changed alternator and problem solved. Make sure you appreciate the time and effort people put into solving this problem for you! JIM