have not started truck in 5 weeks. went to start but battery was dead. ????? never had an issue before!! anyway, the battery charger has been hooked up at 6amps on the drivers side battery{i guess thats the right one} for 4 hours and engine is clicking, but still not charged yet. am i charging the right battery? or do i charge both? maybe i need a new battery since i have only drove 2000 miles this year only with my dmax?