I have fought wont start hot for several years and I might have found a mechanic that fixed it. I did everything Cummins said a couple of times, I changed to run slides inout with engine running to keep batteries fully charged.
I talked to a guy who said it has to be the solenoid on the starter bring it in.
He was instructed by Cummins to remove the solenoid in the driver rear run bay and it will use the one on the new combo on the starter instead. Seeing will be believing.
Might be nice to not have to start gen to get cummins to run