have 100 but no 12 volt HELP PLEASE - on the road

[BirdClemRV]

Monaco LaPalma 2003  Chevy workhorse    Cannot find the CONVERTER.  Do you know its location?
I have 110 volts from shore power and 12 volts at the battery.  But no 12 volts to run house lights, or Air Con thermostat, etc. 
Any advice please. 

 

[Alfa38User]

When you are plugged into 120V shore power, measure the voltage across the battery terminals. If it reads 13.5 or so the converter is running. Slowly walking around your rig when everything is quiet, you may detect a small hum or a fan running which may give away the converter's location. If the Battery voltage is less than 12.5  or so then the converter is not likely functioning. Every manufacturer hides them in different places, so perhaps someone with a similar unit to yours will pipe up with a better answer. On some models, the 120V Circuit breaker and 12V fuse are located in the same panel (often brown coloured) and the converter is built-in  behind that panel.

Have you got a cutoff switch used to disconnect the batteries while the unit is stored? Is it "ON"??
If it is on, you will have to locate the associated big relay and possibly figure out why it has not operated and/or latched. Using a voltmeter is highly recommended...

HTH at least a bit...

 

[BirdClemRV]

More to the story by guy with the problem.  Plugged into 50 amp shore power at 4 PM.  All is well, everything running.  At 10 PM all the cabin lighting, A/C thermostat, switches on smart board shut down.  RV tech came and checked shore power, and every conceivable item he could get his 12V tester on and everything is shows working.  I have a Progressive Industries power surge protector and the LED shows that it is getting the proper power.  Read out on LED is correct.  All the batteries are reading excellent.  The tech spent 2 hours checking and rechecking and could not find the problem.  He has 12 years exp and has never seen this situation. 

 

[Gary RV_Wizard]

Clearly you lost a major piece of the 12v power distribution, but without some specific knowledge of your coach wiring its hard to guess where the fault may lie.  From the battery and converter the power goes to a 12v distribution panle (fuse panel and wiring junction) and distributes from there throughout the coach. I would be checking the board and trying to further isolate what works and what does not. There may be a major inline fuse, plus there is a battery disconnect relay that could have failed

 

[quaddriver]

Id isolate the converter section output wire (typically blue) from the distribution panel and test that for output

 

[BirdClemRV]

Thank you, Gary and Quadriver for your input.  I'll show the tech when he returns to further investigate the issue. 

 

[Weewun]

If your Monaco is like mine the Battery Disconnect is a relay that is picked when DC is available to the Coach.  The Relay is not a latch type.  My relay winding burned open after about 2.5 yrs, resulting in the symptoms you describe.  I ended up bypassing the Relay by connecting both battery feed leads (heavy red wires) to one of the terminals of the relay and taping off the pick wire. 

I have not bothered to replace the relay as I have a Manual Disconnect in the Battery Compartment.  My Disconnect Relay was mounted on the main Chassis fuse board in the front Driver's side compartment.