Charging house battery

A 12 volt battery should read 13.6 volts when fully charged, when discharged/dead, it will read 12 volts or less. When you are plugged into shore power, it should read 13.6 volts if your converter charger is connected and working properly . When the engine is running, voltage at house battery should read around 14 volts. It shouldn't hurt anything to connect a charger to the house battery without disconnecting the battery. It should charge faster with house battery disconnect switch in "off" setting. Your converter/charger may not be working or it may have become disconnected from the battery, check the connections at the converter charger. Disconnect battery connections and clean them and battery terminals, reconnect ALL wires including small gage wires to battery terminals. Check electrolyte levels in battery, add distilled water to cover the plates inside using a bulb type battery filler. Your converter/ charger and/or house battery may need replacement. There is also a solenoid switch that is part of the house battery disconnect circuit which may need replacement. Might be good to find an RV service to troubleshoot your house battery system, rather than just replacing things.