Operation of Norcold 3 way fridge via inverter during travel

Dalehelman · October 2017

I put a watt meter on our 3way fridge out of curiosity. I was quite surprised to see that it only draws a little over 150 watts, and it is on its own 20 amp circuit. On occasion during winter we cook inside. All of the outlets are on one 15amp circuit. So you can only use one hi draw appliance at a time. So I decided to add a power strip plugging it into the other half of the fridge outlet. Placing it inside the cabinet under the sink. Now we can use our microwave and electric cook top at the same time. Since we like others spend months at a time in our T@B and can’t always cook outside. This will work for us.

resize test photo

Image: https://us.v-cdn.net/5021717/uploads/editor/ll/4zq0uxo3z2h6.jpeg

dsatwork · November 2017

Brave sole, no one has ever dared to mess with the 3-way fridge in any way that might create an issue.

I will be watching this post now and want periodic updates. If you survive, others may have the courage to follow your footsteps.

Sharon_is_SAM · November 2017

Wow, only 1.3 amps draw? And on DC it is a lot higher because there is no control of the temperature.

ericnliz · November 2017

@dsatwork, I can probably hear the BOOM from here!

Let 'er rip @Dalehelman!!!

rfuss928 · November 2017

SAM said:

Wow, only 1.3 amps draw? And on DC it is a lot higher because there is no control of the temperature.

1.3A @ ~120VAC or 13A @ 12VDC both are about 150 watts. The same power for either voltage supply as would be expected.

Eji · November 2017

My Nordic 3 way fridge works on power hook up. The little green indicator light stays off when I switch to the battery mood. What am I doing wrong ?

jkjenn · November 2017

Eji said:

My Nordic 3 way fridge works on power hook up. The little green indicator light stays off when I switch to the battery mood. What am I doing wrong ?

The green light should only come on when running on propane.

Dalehelman · November 2017

The green light is not really a light. It is a type of fiber optic that is transferring the light from the propane flame. So no flame no light.

rcuomo · March 2018

According to Norcold installation manual:

DC Operation (3-way and/or fan models only)

12 volts DC voltage

(11.5 volts min. - 15.4 volts max.)

Current Draw

11.7 Amps at 12 Volts DC

13.6 Amps at 14 volts DC

AC Operation

120 volts AC voltage

(108 volts min. - 132 volts max.)

Current Draw

1.4 Amps at 110 Volts AC

1.5 Amps at 120 Volts AC

ChanW · March 2018

No kidding!?! It's actually optical? That's cool!

Thanks Dale! (I love learning new stuff)

Dalehelman said:

The green light is not really a light. It is a type of fiber optic that is transferring the light from the propane flame. So no flame no light.

jkjenn · March 2018

This actually leads to an interesting question...does it make more sense to run the Norcold on AC via an inverter than on DC?

jkjenn · March 2018

ChanW said:

No kidding!?! It's actually optical? That's cool!

Thanks Dale! (I love learning new stuff)

Dalehelman said:

The green light is not really a light. It is a type of fiber optic that is transferring the light from the propane flame. So no flame no light.

Very interesting, indeed!

ScottG · March 2018

jkjenn said:

This actually leads to an interesting question...does it make more sense to run the Norcold on AC via an inverter than on DC?

Based on the Norcold literature cited above, the wattage (V x A) is roughly equivalent on either DC or AC. That suggests it would be an electrically expensive wash either way.

I'm also assuming the inverter itself doesn't consume any power of its own to do its magic. If I'm wrong about that, than using the inverter could actually be less efficient.

ColoradoJon · March 2018

ScottG said:

jkjenn said:

This actually leads to an interesting question...does it make more sense to run the Norcold on AC via an inverter than on DC?

Based on the Norcold literature cited above, the wattage (V x A) is roughly equivalent on either DC or AC. That suggests it would be an electrically expensive wash either way.

I'm also assuming the inverter itself doesn't consume any power of its own to do its magic. If I'm wrong about that, than using the inverter could actually be less efficient.

Depending on the inverter, there is some efficiency loss. 85% efficiency is about average.

RollingBnB · April 2018

ColoradoJon said:

ScottG said:

jkjenn said:

This actually leads to an interesting question...does it make more sense to run the Norcold on AC via an inverter than on DC?

Based on the Norcold literature cited above, the wattage (V x A) is roughly equivalent on either DC or AC. That suggests it would be an electrically expensive wash either way.

I'm also assuming the inverter itself doesn't consume any power of its own to do its magic. If I'm wrong about that, than using the inverter could actually be less efficient.

Depending on the inverter, there is some efficiency loss. 85% efficiency is about average.

My next mod. On 120v the fridge works better and has a thermostat. 12v never seems to stay cold so I am looking for a 200w inverter dedicated for the fridge. This will be for travel only.

Sharon_is_SAM · April 2018

That is a good idea. How different will the amp draw be by using an inverter?

trainwrecked · April 2018

Dalehelman said:

The green light is not really a light. It is a type of fiber optic that is transferring the light from the propane flame. So no flame no light.

Wow, totally makes sense now why the “light” comes on before the thermocouple warms up enough to keep the gas flowing. That always bothered me before, thanks for the insight!

RollingBnB · April 2018

SAM said:

That is a good idea. How different will the amp draw be by using an inverter?

From what I can tell, a 200w will draw 10 amps at full load and can boost to 400w. Since the ac side of the fridge has a thermostat it will fluctuate between load and no load. The 12v now draws 11-13 amps.

RollingBnB · April 2018

So I ordered a 200w inverter, will use the 10gauge wire I ran for the 12v fridge so load will not be an issue. Could use the cig lighter plug but want a more permanent install. Will test next week.

RollingBnB · April 2018

Installed the inverter under the sink and used the 10 gauge wires I ran for the 12v fridge. Ran them thru a battery disconnect switch to isolate the inverter when at a cg on 120v. Just have to move the plug from the 110v outlet to the inverter, turn everything on and drive away. Fridge runs on 110v and thermostat turns things on and off as needed. Best thing is the inverter draws less than the fridge on 12v does.

dsatwork · August 2018

@RollingBnB how did your 3-way fridge 110 setup work? I tried it on my last trip, but my AGM batteries were not up to the job. I depleted them too low, too many times. But while they were working, it was keeping the fridge at 53 degrees with an outside temps over 100. Not meat worthy, but we have relegated the 3-way too a veggie and fruit crisper. Since all we use is almond milk, it's safe for that and our probiotics that need to be stored in a cool place. Oh yeah we kept eggs, salsa, tortillas and our non-dairy cheese. Any thing that needs to be kept 40 degrees, stays in the ARB in the tow vehicle, that stayed on the entire 14 days.

RollingBnB · August 2018

@dsatwork So far it's worked great. TV keeps the battery fully charged and the frig stays @ 36-40 degrees. Heading out on a month long trip soon so it will get a real test.

ChanW · August 2018

Well, I got to say, I love your solution @RollingBnB. Way better!

dsatwork · August 2018

RollingBnB said:

@dsatwork So far it's worked great. TV keeps the battery fully charged and the frig stays @ 36-40 degrees. Heading out on a month long trip soon so it will get a real test.

Please let me know how it goes

RollingBnB · August 2018

dsatwork said:

RollingBnB said:

@dsatwork So far it's worked great. TV keeps the battery fully charged and the frig stays @ 36-40 degrees. Heading out on a month long trip soon so it will get a real test.

Please let me know how it goes

Will do. It has worked fine for short (250 miles) trips, will see how it holds up on a 7,000 mile trip. My concern is how well made is the invertor. The frig thinks it's plugged into shore power so no issue there.

ChrisK · August 2018

Dalehelman said:

The green light is not really a light. It is a type of fiber optic that is transferring the light from the propane flame. So no flame no light.

This is not correct for all fridges. Mine (2014 Max S with Norcold 3 way) uses an actual light. How do I know? Mine failed and I replaced it with the factory part which is an electrical light. The only thing going to it was wires. No fiber optic cables.

RollingBnB · September 2018

After almost 30 days and 7k miles the inverter test worked great as long as I remember to turn on the lights in the tv. Ran the fridge on 120v while driving and it stayed at the set temp no matter what the weather was like. I’m happy with results.

Tabaz · September 2018

Glad Alan found a very clever solution to his problem! Mine was slightly different. I was running the Norcold on 12v and my ARB 50 quart fridge from my Ford Expedtion will in transit. The 7 pin connector would not supply enough power to the Norcold. Result was depleted TAB batteries upon arrive at the campsite. Solution was to run an 8 gauge wire from the Ford battery to the TAB batteries on a separate line from the 7 pin connector. I now can run my Norcold AND ARB off the Ford battery while in transit without depleting the TAB batteries. As an added bonus, The ARB runs off the TAB batteries via a separate line to then while at the campsite. VERY happy with results. Many thanks to my good friend and his Dad for sorting this all out.

RollingBnB · September 2018

I only have the one item to power but it is all the 7 pin can handle

Operation of Norcold 3 way fridge via inverter during travel

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