'06' monarch House electronics not working.

[RickAvery]

Just returned home from a short 100 mile RV trip and when I shut the engine down none of the house electronics ie. lights, slides, water pump... would work. When I restarted the engine, they would again operate. They would also work when plugged into shore power. Both the chassis and house batteries are showing ~13vdc with the engine off and no shore connection. The house batteries are 4 Interstate 6vdc deep cycle batteries in the traditional 2s-2p configuration they are 3.5 years old and have performed flawlessly from day 1. An inspection of the electrolite levels shows all of the cells at 1/4" or greater above the plates. I have a 4 stage converter which is always plugged in when parked. Anyone have any ideas as to what the issue might be?
Thanks
-Rick

[dougrainer]

RickAvery wrote:
Thank you for your reply. Yes, the house batteries are at 13.0vdc.
Does anyone know where the battery boost relay is located?
Thanks
-Rick

Monarch 2006 Gas engine? Battery boost is usually located in the Left front storage in front of the LF tire. BUT, this solenoid would NOT even remotely be your problem. The fact you have coach power when engine ON shows the boost solenoid is functioning. Page 198. Doug

https://www.monacocoach.com/resources/media/manuals/2006_Monarch_SE.pdf

[RickAvery]

Thank you for your reply. Yes, the house batteries are at 13.0vdc.
Does anyone know where the battery boost relay is located?
Thanks
-Rick

[ArchHoagland]

Have you measured the voltage at the house battery terminals with a voltmeter?

[RickAvery]

Thank you for your replys, yes, I've checked the cut-off switch and it appears to be working properly. There is also a hard disconnect in the battery compartment which disconnects the main positive lead in which case, nothing is activated and this is also working correctly.
I will check out the negative cables in the morning.
Thanks again
-Rick

[Tom_Barb]

The main battery negative cable is off, broken continuity , or
If the main disconnect switch is open, nothing woks on the alternator, or the 50 amp cable.
the engine alternator has it's own ground, as does 50 amp circuit.

[Bruce_Brown]

Is the 12v cutoff switch on?