Went away for seven weeks. When I came back car was dead and would not accept charging to the main battery. Finally had to get a heavy duty charger for the 12 volt which runs the computer systems. After boosting the 12v the car would finally accept charging to the main battery. Since the big battery usually feeds the 12v I was stuck until I got the 12v boosted. Why did the 12v and the big battery both go to zero in 7 weeks? Is leakage that bad?