12 Volt Frig Relay

To answer a few questions. This is a small dometic fridge commonly called a cube fridge because the dimensions L-W-H are equal. These older friges do not have a circuit board. The LP flame is lit manually. The 12v heater has an on/off switch (fused) to turn 12v use off. To power the 12v heater I would have to connect into the 12 circuit or batt. preferably. On this 2000 Ford PU the OEM 12v relay kills the 12v circuit but the Frig is connected to the batt. and will draw power. Could flip the fused switch but if I forgot .....well you know. Soooo I would place this new relay between the frig and the RV batt. I would place the frig in the 12v position only when starting out if the frig was warm other wise the frig would stay cold enough until the next stop and LP operation resumed. When traveling the LP flame is not 100% reliable much like the driver.

KISS

Flip the switch

We run ours exclusively on 12v when on the road. Did it for 8 years before adding auxiliary charge line and ignition controlled relay to shut off refer with truck. Running out immediately when stopping for 5 min to keep batteries from discharging got old. Also shutting down refer last hour or to ensure batteries charged when arriving at camp.

Adding the ignition controlled relay simplifies usage on 12v, running auxiliary charge line makes it more practical as far as battery charging and refer 12v use. We also now have solar-running the refer on 12v just is not an issue. Running on 12v is the least efficient but it does work. That said as MOST will tell you you cant or shouldn't so I would be hesitant to recommend. Why it worked for us and seemingly no one else, especially for the 8 years prior to upgrades, I cant say.

Couple of thoughts-
Verified you have sufficient 12v supply to run refer when truck running? Looking back it appears you've added 10ga charge line. Have you tried to run the refer on 12v while traveling and can truck keep up? No sense going to effort of relay if it kills your batteries and milk is still warm?
Second is you said "sparingly for short runs not for continuous use".. If thats the case, the refer pre-cooled & closed will keep cool for a few hours with out running at all.
Third have you verified that refer will respond as you expect. IE set to run 12v, once on- disconnect the 12v source, pause then reengage-Does refer come back on in 12v mode. Some when source power removed then reapplied the board will default to off position. (so running a relay wont work).

IF you decide to add the ignition controlled relay, Id recommend adding manual switch to relays ignition trigger wire. Also, though it is as simple as adding a ign. controlled relay, you'll also need to run a 12v source selector switch, either directly to battery as normal for propane use or thru the relay. Could be as simple as an on/off switch (30amp toggle) on source line with the relay as a bypass.

OP: I just looked at your profile.
Is the refer in question in the pop up camper?
Some pop ups do not recommend running refer on propane while collapsed.
If it is does the refer have two vents when collapsed?
Is this a three way refer?
Make and model of refer would help.

Personally, I would correct the flame going out. Another question I have, is what kind of Fridge do you have (make and model)?

I think you would get more responses from the Tech Forum, so I am moving this Thread from the TC Forum.

Wayne
Moderator

enblethen wrote:
Small ice cube sized relay from auto parts stores would fit your bill. I would wire it into an ignition switch hot in run position. It would take an extra wire.
Before doing this I would attempt to find out why the refer blows out.
Are the flame covers in place? Have you checked to see if the flame sensor is real close to the flame and in direct path? If yes try using a secondary heat shield. Even a piece of aluminum foil may help.

X2 I believe you want a NC relay that opens with the ignition on.

Not sure this is necessary as the propane should shut off when the flame goes out.

Small ice cube sized relay from auto parts stores would fit your bill. I would wire it into an ignition switch hot in run position. It would take an extra wire.
Before doing this I would attempt to find out why the refer blows out.
Are the flame covers in place? Have you checked to see if the flame sensor is real close to the flame and in direct path? If yes try using a secondary heat shield. Even a piece of aluminum foil may help.