12 volt questions

As Trackrig said, that is a battery isolator relay. It connects the chassis and house batteries together, probably based on when the engine is running (and possibly also controlled by an "emergency start" button or switch.

The battery disconnect switch in 5 I would suspect connects the house battery to the 12V distribution panel (typically via a latching relay). Usually these are momentary center-off switches, though, which this does not appear to be. I would be rather surprised if the isolator is manual on this vintage of a motorhome.

If you're parked for a few months, you definitely should either disconnect the battery (once its charged) or have some arrangement for keeping it charged while connected, such as plugging the RV in to shore power so the converter is on or having some solar charging setup. If it's not cold winter weather, you should periodically charge the battery even if its disconnected due to self-discharge. Self-discharge rates vary greatly with temperature changes; in freezing temperatures, it takes months to self-discharge the same amount that happens in a week or two of hot weather.

There's no way to tell what the fuse is for without tracing the wires or removing it and seeing what no longer works. One possibility might be the CO and propane detectors.

The thingybob near your thumb is a Stinger 80A Battery Isolator and Relay.

Stinger on Amazon

Bill

The WFCO converters are known for not going into boost mode, thus they don't charge as fast as other 3 stage converters. They also seem to break down more.

This is based in what I have read in this forum. I don't have a WFCO, but a PD9260.

tenbear wrote:
I don't see a converter, only a power distribution panel. The converter may be behind the panel, or maybe underneath it.

I found mine on line after getting the model number.
http://www.rveparts.com/wfco-converter-wf8955an-pec-55-amp-power-center-rv-parts/

tenbear wrote:
I don't see a converter, only a power distribution panel. The converter may be behind the panel, or maybe underneath it.

Yes the convertor and the fuse panel are one unit I think. I'll check behind and see if there is another name on it.

MrWizard wrote:
battery disconnect, turns off the house side from batteries

it does NOT separate house and chassis batteries
that is done by the charge 'Isolater' , which is either a diode base device (big finned heat sink with heavy wires on it) or a relay controlled by the ignition switch

Thanks, I know about the diode/ relay isolator as I replaced the one under the hood of my former "B".
Now that disconnect explains why my batteries ran down as I had the switch off thinking it separated the coach from house batteries.

I don't see a converter, only a power distribution panel. The converter may be behind the panel, or maybe underneath it.

battery disconnect, turns off the house side from batteries

it does NOT separate house and chassis batteries
that is done by the charge 'Isolater' , which is either a diode base device (big finned heat sink with heavy wires on it) or a relay controlled by the ignition switch

The item by your thumb is a relay. The yellow wire looks to be the control wire to it.
That could be a battery disconnect. In last photo the switch on bottom should go to battery disconnect relay control.