Fxrscotty, you could have an isolator between the two battery banks. You need to check all wiring at it. Check to see that you have 12+ voltages on both sides with engine off and then start engine and voltages should increase. If it increases on one side and does not increase on the house side then the isolator is bad. You can do the same kind of testing if you have a charging controller circuit and solenoid type. You will also want to verify that your batteries are good. Good luck and let us know the out come.
Mike, RVIA & RVSA Certified Master RV Technician
Amy, Dr. Assistant - Roxie & Mei Ling, four legs each
2000 Gulf Stream Scenic Cruiser 450 hp & 1330# torque
06 Saturn Vue, 06 Chevy Z71 4x4 & 2014 Corvette Z51 M7