RV fridge in Force HD

[djmedel]

Does anyone else have the optional Norcold RV fridge in their DX3 or Force?
I think mine is not wired correctly.

When I remove the AC power the fridge continues to run on AC even though it is set to auto and the propane is turned on at the tank.
This causes the batteries to go to 11.8 volts in about 8 hours and it still doesn't auto switch to propane.

I believe it is on an inverted circuit and should not be.

[SeaDog]

You can test your theory by unplugging the 110V power at the frig and see if it switches to gas and your batteries stay up.

[bclemens]

All our Fridge circuits are inverted. You would want to put the fridge into LP Only mode.

[djmedel]

Brian,

I think that the RV type fridge should not be on an inverted outlet.If you lose AC power it draws 50 amps from the batteries and drains them quickly.The refer has the ability to automatically switch to propane when in auto mode, so one less thing to think about when moving from place to place or camping without hookups for a night or two.

[bclemens]

opinion duly noted.

You could also just turn off the inverter. Maybe that is simpler? The problem with not inverting it, is if there was ever a reason you wanted it inverted, you have no options. Having it inverted means you could (maybe ran out of LP) use the inverted circuit. While this way does require some more user input, it gives you maximum flexibility.

For rigs like the DX3, we invert the entire coach. So to take out one outlet in the rare instance we do an RV fridge, is asking for errors.

[formerFR]

I'm not sure why someone would not WANT it to be on the inverter, as any residential RV fridge is. It also does NOT draw 50amps, wherever that came from(?), but only about 3-8amps depending on the size and type...and it only uses 'amps' when the compressor is running, not 24/7... typically only about 10 minutes at the time, several times per hour.

In your situation, you wouldn't want to use 'auto' if you have your inverter on, as the fridge is still 'seeing' 120v power, if so.

[djmedel]

There is no compressor on my absorption fridge

[formerFR]

I guess my point is that your fridge will actually draw much less than what you think, when on 120v power from the inverter, especially since it doesn’t have a motor(compressor)... you could last even longer on the inverter than most of the rest of us : )

[djmedel]

I checked the 12 volt side going to the inverter with a DC ampmeter and it reads 48 A with only the fridge running

[formerFR]

gotcha, but that’s 48amps at 12volts, not at 120volts for the inverter, Shore, or Gen power... but the conversion would be at only about 3-4 amps.
if you have just a single 12v 100ah house battery, you could easily run the fridge for 10hours, without being down to 50% battery capacity

[djmedel]

I have two 200 amp batteries. You have roughly half of that usable before the voltage drops below 12 volts. So at a 48 amp draw I can run for about four hours before I have to plug in or start the generator.

[FOURWHL]

But your fridge doesn’t run constantly

[djmedel]

I guess that’s why it takes about eight hours to get to 12 volts.

[mikew968]

I just looked at two norcold units and they draw 3.8 and 5.3 12v amps. You might google the model and see what the draw spec is.

[Thebackpacker]

The Norcold absorption refrigerator always draws a few amps of DC power, whether the refrigerator is operating on AC or LP. If operating on AC, in addition to the DC power requirements, the refrigerator requires 450 watts at 120 volts AC ( 225 watts for each of two electric heaters), which operate in place of the 2,400 Btu/hr from the LP burner. See Specification on page 7 of Norcold Service Manual121X Series Gas/Electric Refrigerators at
http://rvrefrigeratorrepair.com/wp-c...d-Service-1210

As watts equals amps X volts or, rearranging, amps equals watts divided by volts, then 450 watts divided by 12 volts equals 37.5 amps plus the few amps of DC power which the refrigerator is always drawing.

An advantage of the refrigerator operating on the inverter is that it can be operated on electric when driving. The DX3’s 275-amp alternator is capable of supplying the energy to keep the coach batteries charged even while operating the refrigerator.

Another consideration, some people advise turning the LP valve off at the tank for safety while driving.

An advantage of having all of the electric outlets on the inverter is that you can use an electric coffee pot or microwave to make coffee for a coffee break, which is more convenient than the LP range. Just don’t operate either for very long without the alternator or generator operating.

If you leave the Xantrex set to start the generator automatically when the coach battery voltage is low, you should not have to worry about low coach battery voltage.

Thebackpacker
2016 DX3