Lights won't turn on without being plugged in

Hi everyone,

I have a 1992 Flairwood Fleet.
Currently the coach battery won't charge and the lights won't turn on when not connected to the wall.

I replaced the fuses inside the motorhome but this didn't seem to fix it.

Could this be the relay? If so, where is it located?

The issue happened when the motorhome was plugged in while the generator was running which I think is a big no-no.

Any ideas?

I'm supposed to leave tomorrow morning for Burning Man.

Thank you,
Cody

A Fleetwood Flair maybe?? 
"Currently the coach battery won't charge"...  "and the lights won't turn on when not connected to the wall."

I assume you mean with the engine running???  You are referring to outside power (by your 30 amp cord??

What position is the battery "Use/Store" switch in? The relay associated is a fairly large one and can usually be heard (a clicking sound) when operating the switch to help locate it. The same also goes for the relay used to connect the jump start key on the dash and they are often mounted side by side.

"The issue happened when the motor home was plugged in while the generator was running which I think is a big no-no."

The Automatic Transfer Switch (ATS) should be able to handle it but that can result in burned/stuck contacts if done too often and with a load connected. I don't know where it might be located in your motor home but if you are able to, you can trace the cables from either the generator output or the power cord, they both end up there.

There will be a circuit breaker located on or near the generator as well as well as one or two polarity protection fuses directly on the converter (or perhaps on the power distribution panel) that, if blown, may cause this problem. Also, check the house battery charge, you could have dead batteries. Do so with a voltmeter right across the battery terminals. If the converter is working you should see 13.2V or so, if not... well, you will need to tell us what you see. While you are there, check the water level in those batteries adding distilled water if needed.

The lights are 12v powered, so require either battery power or shore power to operate the converter/charger (the alternate 12v source). You stated the battery is bad, so that's most of your answer right there. It could also be that the battery is offline, i.e. the disconnect switch that Stu mentioned.