Chassis Batteries not charging

How old are the batteries?

Well Sir,
You've been given some good info. Since I don't know your model of coach you have, based on what you're saying, it sounds like a gas coach. If so, most of those are equipped with what's called a "Converter". Now, some of them are also, "Converter/Chargers". Basics are: A Converter changes 110VAC to 12VDC and, a Converter/Charger also charges mainly the "COACH" battery(ies).

So, the first thing I'd do is, dig around in your paperwork or, manuals and find out what exactly you have. If it is a Converter/Charger, then you'll have to determine if it's doing its job of CHARGING the house batteries while being plugged into shore power. The simplest way to do that is, using a VOLT/OHM meter, check your house battery(ies) when NOT plugged into shore power or, having the main engine running.

Record the voltage. Then, plug the coach into shore power and, check the coach/house battery(ies) again. If you find a higher voltage than before, it would seem the Converter/Charger is doing its job. But, if you find no difference in voltage at the house battery(ies) after plugging in and, you're CERTAIN that you have a Converter/Charger, then something's amiss in that circuit.

I don't know those very well so, it may be something as simple as a fuse on or in, that Converter/charger. Now of course, as has been stated, always make sure that your house battery(ies) are in proper condition and, plenty of water and, have good, clean and tight connections and, the cables are in great shape.

And, along with that is making sure that your ground cables and ends where they attach to the frame etc. are clean and tight. So, those are a few points to start with. Good luck and, do post back if you find the problem(s) so that others may learn.
Scott

Chassis battery starts the main engine. House battery powers the living area of the RV.

You need to check the voltage on your charging system.

The coach batteries is what runs most of the 12 volt systems in your rig.
I would say you should start by cycling the battery disconnect. Turn it to store or off, then turn it back on. Have a 12 volt light on. See if the light becomes brighter when turning system on.
You could have a bad converter, reverse polarity fuses are blown or the main fuse from the converter is blown in the 12 volt DC distribution panel.
Verify that there is 120 volts to the receptacle or input to the converter. No 120 volt, reset all 120 volt circuit breakers, don't just look at them. Turn all breakers off applying light pressure toward off. Then turn on main breaker. Then turn on branch breakers one at a time. Give the system 10-15 seconds between branch breakers.

Easy to troubleshoot. Get your jumper cables, and connect one leg to the negative. Connect the other end of the cable to a piece of wire and put it on the negative output of your converter right where it comes out of the converter. Did the lights get suddenly bright? Yes... the negative return is not tight somewhere back to the battery. No.... Disconnect the negative from both ends, and do the same with the positive from the battery to the positive output of the converter. Did the lights get bright? Yes, it is the positive feed from the converter to the battery.

If either of those work, it is just a loose connection. If not, you have to have a meter and see if your converter is working or not. If not, check power in first with your meter to ensure 110 is there, then check output of the converter right at the output terminals where you put the jumper.

Only after you have figured out the actual problem should you start looking for the answer to fix it.

Always check contacts first. Clean positive and negative terminals and ground connection. Do this with no power drawn or being generated or shore power. Many RV's suffer from corroded and or loose connections due to moisture and road vibrations. Of course the water levels have to be right in batteries and only used distilled water to bring them to level. No matter how good grounds look always disconnect and wire brush the contact points on chassis and wires, then reconnect and spray with battery terminal anti corrosion.

I recently had all three 30 amp fuses on the converter blown. Of course, I hooked up the batteries backward, but I was left with the same symptom. Be a place to start.

Household 12 VDC appliance should NOT be powered by the chassis battery. The HOUSE battery should power them.

So, first task is to verify "what runs on what".

Also, verify which battery bank the solar charges.

Be aware that on many coaches, the chassis battery is NOT charged by the converter or charger.