Trouble with Auxilary batteries

Articles about RV electrical systems:

BATTERIES--AND OTHER ELECTRIC STUFF

The 12v Side of Life

Intro to Dry Camping

Battery Education

Sam Spade wrote:

cencerrita wrote:
Get it checked with a load tester which any auto shop will do for free.

This.
And you need a volt meter for yourself.
The fact that the panel shows the batteries dead either means that they ARE dead or there is a bad connection somewhere.
Someone else had a similar problem recently and it was a cracked main fuse for the batteries. Other things are possible too.

What Sam said. Get a multimeter. They are so stinking cheap these days you can have several. I have about four of them. One lives in the RV full time.

I have 3 of these: LINK

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.

cencerrita wrote:
Get it checked with a load tester which any auto shop will do for free.

This.
And you need a volt meter for yourself.
The fact that the panel shows the batteries dead either means that they ARE dead or there is a bad connection somewhere.
Someone else had a similar problem recently and it was a cracked main fuse for the batteries. Other things are possible too.

You say you have power from batteries for lights but not enough power to turn the generator over. Just because the battery has a full charge does not mean it has the capacity with modern batteries. Get it checked with a load tester which any auto shop will do for free. This is a common problem with cars now and modern batteries. You drive home and battery is fine, stop the car and there is not enough "umph" to start again as battery has died.

Do your lights dim when you try to start your generator? If so, the battery or the wiring has a problem. If the lights don't dim, the auxiliary batteries are not connected to the genny. I am assuming the auxiliary batteries are your coach batteries as opposed to the chassis battery.

Get voltmeter and check voltage. Google 12volt side of life, read and learn

Do you have a battery disconnect switch on your RV?