I just discovered that the house battery disconnect latching solenoid on our rig was not working because of dead house battery. I started the truck engine and the engine's alternator raised the voltage in the house battery so that when I pressed the house battery disconnect switch there was a loud snap. I shut the engine off and then there was 13.2 volts at the battery terminals, indicating that the converter charger was working properly on 110vac shore power. A fully charged house battery should read over 13 volts, 12.5 volts may be too low to start the generator, voltage drops under load of generator starter trying to start the generator. If you start the engine, the voltage in the house battery should rise to around 14 volts and the RV generator may start. If you use the starter switch on the RV generator itself, it may start more readily than pressing the generator switch on your inside control/monitoring panel. Using the "emergency start" switch on your dash board connects house and starting batteries in parallel, which may start your generator, also may start the truck engine when the starting battery is low/discharged. Check electrolyte levels in house battery(s) and starting battery, add distilled water as needed to cover the plates with a rubber bulb filler. Clean corrosion from battery connections, make sure to connect all wires with ring terminals to the same battery terminals. When plugged into shore power, with converter charger working properly, and house battery disconnect switch in the on position, you should read over 13 volts at the house battery. With truck engine running you should read over 14 volts. Voltages are dependent on condition of the house battery and good clean/tight connections at battery terminals and good ground cable to frame connection.