Voltage of Coach Batteries

[Mmnsc]

This past weekend I noticed the voltage on the gauge and digital read out seemed low. On the gauge as driving along it seemed to read about 13 volts and the digital read anywhere between 12.3 and 12.9 volts. I think my voltage regulator or alternator may not be working correctly. I always thought the running voltage should be about 13.5 volts. We drove approximately 250 miles with this seemingly low voltage. Does the diesel use electric power to keep running the same as a gas engine does since there is no ignition or spark plugs? I just don't know enough about how a diesel works.

When running the generator while driving, does it charge the coach batteries or just the house batteries? When plugged into Shore Power, does the invertor charge the coach batteries as well as the house batteries? When nothing is operating in the camper, there is a hum, sounding like a fan running, coming from the invertor and stops if I turn off the switch to the house batteries. Is that normal as I don't recall hearing that before?

I know the electrical system is very complicated on a MH and understanding the ins and outs are very challenging.

Thanks

[tmmar]

Marty,
I think it depends on which inverter you have as to whether it charges both the house and chassis batteries when on shore power. If you have a 2000w inverter, it will charge the chassis batteries after the coach batteries are charged. I don't think that happens if you have the smaller inverter. I also think that the diesel engine uses some electric to power the fuel pump and gauges. I would think that running the generator would only charge the house batteries and not the chassis batteries.
Tom