Twice so far, my dad's 2002 dully lb7 would not start. I have a snap on obd II scanner.. There were no present codes,and none in history.. The voltage while cranking was only about 9 volt, I jumped it with my cummins, and it started ok. My dad refused to buy two new batt. Because one was "only three years old".. He put one new batt.,, but two days later,, same problem,, with same result after jumping with cummins. Question now ,, is the older batt. NFG? Or are these lb7 known to have a draw problem? The alt. is charging at 14.7 v..if it sits to long,, voltage drops to low for the computer to turn on... Any thoughts??

 

Replace both at the same time my lb7 03 is on the fourth set