Trouble with Auxilary batteries

If your house battery(s) is old and tired, a voltmeter or the meter on your battery charger may indicate a full charge. When you try to start the generator, the load of the generator's starter may be too much for your tired battery(s)and voltage drops way down. If you could leave the voltmeter connected to the battery, while attempting to start the generator, you could see the voltage drop drastically and rise back up when you stopped cranking the generator. New batteries with fresh plates inside have much more stamina than old ones with sulphated plates. Our two T-105 6 volt in series batteries lasted about 10 years then needed replacement. Your house battery should read around 13.6 volts when you are plugged into shore power and your converter/charger is charging properly. When your truck engine is running, you should read over 14 volts at your house battery. When engine is not running and you are not on shore power, you should read around 12.6 volts. If your battery reads around 12 volts it is nearly dead, can't start generator and interior lights will be somewhat dim. The LED battery charge indicators in the panel are not accurate, often show full charge when battery is worn out.