What is supposed to work on battery?

[Elvis]

When my 2017 MW is disconnected from shore power, nothing behind the cab works. No lights, no outlets, nothing. The switch by the door is ON. The batteries show full charge. Is this the way its supposed to be? I cannot figure out what the batteries are for if they don't work even the lighting! I am researching the owners manual. thought I would seek input from the pros as well. Thanks!!

[sundog964]

What is the state of charge in the batteries?

[Morich]

Yes, most all the 12volt lights, fans, etc should work so the big first step might be to ask about the battery disconnect switch.
We don't get lots of indepth info on trailers to check but most disconnect switches are connected a to a latching relay which actually does the disconnect.
Kind of situation where small wires that fit into small switch make a bigger relay handle the larger wires that do the work?

So when somebody is close to the relay, and the switch is pushed each way, one can expect to hear or feel the relay move. Not terribly loud but usually we can expect to hear/feel a click as it moves.

When new to the feel of the disconnect switch it can be easy to miss accually getting it flips as it is a different type as it is momentary, so try pushing it several times to off and back to on to see that the disconnect is not the problem.

If nothing there, try the breaker panel and flip the breakers off/on to make sure it is really correct as just a look can miss one flipped at times. One trick to avoid getting out a meter is to turn some switch like on a vent fan or light that you KNOW, for sure means that item is on and then try the relays and breakers while watching that item.

[creativepart]

All 12v items inside you Minnie Winnie should be operating on battery. That's your lights, your fans, all USB ports, your outside awning, water pump, your propane furnace, your fridge and likely your TV. You must have charged house batteries, of course. And have the house battery disconnect set to ON. It's possible you need to turn on your inverter on standby if you have one - that would be covered in your Operator's Manual.

[Elvis]

Thanks fellows. I move that switch and hear no noise, no click, nothing. I know that main door switch USED to work well, for whatever reason, it may have stopped. I will check the inverter via the owners manual.

[armullis59]

I had this happen to me once and doing a reset on the inverter fixed it. Also, check your GFCI plugs for a tripped breaker. Resetting one GFCI may enable multiple 120 volt plugs.

[Morich]

Doing a look at some of the 2017 models of MW, I see what may be a newer version of the disconnect relay and it may be something that is quiet so that we might not hear it move???

Are you familiar with where that is located and might be able to check that coach battery is getting to it and then passing through when the disconnect switch is moved?
This is a snip of the parts drawings to show where it should be found if you can get to it and verify that power is getting to it and it is working.

Also a point to think about may be how the battery voltage is checked. It's a small point but one that can drive us crazy if we put a meter on the post of the battery and see good voltage but don't check the clamp to see there is not corrosion, etc. keeping the voltage that is in the battery from getting from the post to the cable!!

Sounds really snotty to mention something so plain but I find most of us are prone to doing that sort of thing! I think it's called "human" !!

Also it may tell you something if you try having something like a light turned on and then start the RV engine, does that make the light come on, even when not plugged into power. Starting the engine has a mode solenoid which should automatically connect both batery sets together with the engine alternator to get some charge into the coach batteries as we drive, so if it lights things up by starting the engine, it points more toward something not right with the coach batteries, rather than a switch or fuse/breaker, etc. being the problem.

[Hittntheroad]

You should have a 12 volt breaker close to the batteries. Usually has a little flag that pops out to show it’s tripped.
It may look like this

[GiGi]

I am not sure if it’s the same, but I had a very similar problem this summer. Nothing worked when I was unplugged and even when I was I had certain things, like my front shade, that wouldn’t work. I replaced the coach battery and everything is working great again.

[Elvis]

To SUNDOG964,
I dismissed your answer out of hand because the battery indicator lights said FULL CHARGE. Upon further review, it only indicated full charge while shore power. (I'm an idiot) After inspection, I think original batteries. I just bought the RV, kinda wondered why the seller always had the engine and generator running. Bottom line, NEW BATTERIES ($190) and it all works perfectly. Thanks for indulging my ignorance and sharing your knowledge. That goes for all on this site. VERY helpful
Happy Camping!!
Now, I need to get a battery monitor hooked up. Recommendations??

[Morich]

It may be late to mention and sound like critical but meant to be helpful, but you may have fallen into a trap that most of us find at some point!

It is never too late to mention the way batteries work can confuse us if we forget. The battery is a chemical reaction and it is SLOW to charge, so when we want to know the charge, we need to take the battery charge off and if we can, cut the items using power, to get a better actual idea of the charge left.
If we look while charrging, it it slike you spotted, we get the voltage coming out of the charger and no real idea if the battery will store that charge.
If we read the voltage too soon after the charge we still get what we often call "surface charge" readings and may come back an hour later and find it much, much lower!

No big thing but something to try to keep aware of to avoid chance of confusion.