Jim,

With engine running my chassis meter reads 27.7v without OTR air and 27.5v with OTR;

With engine off, ingnition on my chassis meter reads 24.7v

House meter reads 27.4v to 27.8v with engine running (difference depends on if the OTR air is running. I also have a switch were I can show the house side in 12 volt.

Plugged in the house meter will typically read around 13.0v to 13.2v (I usually keep the switch on the 12 volt side) if I have just shut down and I am not using a lot of 12v lighting.

Unplugged with the refrigerator running off the inverters, the house meter reads about 25.5v after 3 to 4 hours or 12.7v with the meter switch on 12 volts.

I have a vintage coach with the Driptroit 8v92 so the readings may be different for the Series 60 for which I lust.

I rarely charge the chassis batteries because we use the bus pretty regularly. I keep the battery charger on (older bus with a separate charger not built into the inverter) most of the time on the house batteries and it keeps them at about 13.3v with the switch on the 12 volt side.