DC Fridge Shipped To Home Depot

[spyderRV]

look at the refrigerant in some of these newer smaller fridges, it is similar to propane, flammable much?

[HISSSSS]

Originally Posted by spyderRV

look at the refrigerant in some of these newer smaller fridges, it is similar to propane, flammable much?

My NovaKool uses R134a (a R12 replacement) which is non-flammable. Even if the fridge used R410A, it would be considered non-flammable as the flammable component of R410A, R32, is at a low enough concentration that the resulting mixture is non-flammable as flames will not propagate per ASHRAE research done about 8 years ago as I remember.

If the fridge did have propane as the refrigerant, R290, it would be is a very small quantity due to the volatility of the propane. An absorption refrigerator is more dangerous as the propane is used in an open system (i.e. the flame) vs. a closed system where the propane is hermetically sealed inside the refrigerant piping.

Due to poor cooling of my old Dometic fridge plus the possibility of a fridge fire were the reasons mine was replaced.

[theoldwizard]

Originally Posted by okmunky

I think those who have residential fridges don’t boondock much. If you only drive from RV park to RV park your alternator will keep the batteries charged enough to run that much power thru an inverter.

I live on solar power so I have a DC fridge.

I agree ! I would still like to see a "side-by-side" comparison of current draw for a DC fridge and a similar size residential fridge and modern inverter.

[okmunky]

Originally Posted by theoldwizard

I agree ! I would still like to see a "side-by-side" comparison of current draw for a DC fridge and a similar size residential fridge and modern inverter.

With the AC fridge that's easy. Just plug in a Kill-a-Watt meter. I don’t believe they make a DC version so measuring the DC draw can’t be as exact.

I have confirmed that my Nova Kool FRU 9000 uses 5.2 amps when running by watching the Trimetric battery monitor when it turns on. What I can’t measure is the total amp hours it uses. I can only guess that it runs 15-20% of the time. Mostly during daytime hours which are normally replaced on sunny days.

I would like to see a true comparison also.

[okmunky]

Astrocamper -

My new Nova Kool 9.1 Cu ft DC compressor fridge fit the cabinet that the old Dometic 6 Cu ft came out of with an extra half inch on top.

This link will give you the specs

https://www.suremarineservice.com/Ga...RFU9000DC.html

Don’t worry about it being out of stock. They special order each one. They are made just over the border in British Columbia, Canada.

It's the best upgrade I’ve made to my coach!

[nvs4602]

Originally Posted by astrocamper

I was in my trailer doing some work getting my Dish satellite system going. It will be nice having some TV when I am completely off the grid and away from Cellular and broadcast TV.

I removed the furnace return panel under the fridge. I also measured the rear height of the opening for the fridge. I don't have the room for a taller fridge. The 6 cubic foot version will have to do. It is small enough to fit in the existing opening.

I have a trip coming up in a few weeks. I recently added a fan inside the fridge and a better pair of fans at the intake vent. I hope the Norcold does better in the heat. If it can't keep up on the hottest days I may swap it out. I added a display unit that shows the temp inside the fridge and freezer. I ran the fridge for about 6 hours to test it out. The freezer cooled down fairly quickly but the fridge was not ready for food after 6 hours.

In the past I put a lot of bottled water in the fridge and freezer and give it 48 hours or more to get down to stable temps. On the hottest days I will move frozen water bottles from the freezer to the fridge to give it some help.

I will have about 2 months to order and install the DC fridge between the trip coming up and a longer one in September if I decide to do so then.

Norcold will perform at 110 degrees ambient temp. When it is properly vented and in a suitable enclosure. What tends to happen is manufacturers build the enclosure is less than ideal enclosures or to Norcold's requiremen's. I did test and design on these a ND Dometic refrigerators side be side enclosures at 110 degrees. Meaning the whole enclosure was in a room at 110 degrees. Ran them on gas and electric to check their performance. Now this was back in the 90's so some things could have changed but norcold always out performed dometic in these test. If your frig isn't keeping temperature then you have ventilation problem. There should be ZERO dead space between top, bottom and sides of refrigerator. The roof jack vent should be directly above the back of the refrigerator not inboard. That is why adding fans behind the refrigerator improves performance. Personally I would not be afraid to run a gas refrigerator as long as it is installed right. But I've seen some manufacturers installation and I'm suprised norcold or dometic work. And please don’t be one of those people that think that the bottom outside vent is just another storage space. I've seen people put wd40,rags etc.

As one other person said Norcold makes a direct replacement, (or did). Compressor model that runs on AC or DC . These compressor type refrigerators where originally designed for boats so you know they can take a beating better than a standard compressor frig.

[richard5933]

Originally Posted by theoldwizard

I agree ! I would still like to see a "side-by-side" comparison of current draw for a DC fridge and a similar size residential fridge and modern inverter.

Our Vitrifrigo 12vdc fridge consumes about 5.5 amps while operating, according to our Victron monitor. It operates about half the time, of course this depends on ambient temps. That results in about 66 Ah per day of use @ 12vdc.

I just looked up the specs on a tiny residential fridge - an under counter 1.1 cu ft. dorm fridge. It's specs say that it consumes 1.1 amps @ 120vac while running. Assuming it also runs half the time, that would make 13.2 Ah per day of use @ 120vac.

Here's the rub, the residential looks to be doing better so far but it's not. It takes approximately 10x the dc amps than it does ac amps to run an appliance. In other words, in order for your inverter to make those 1.1 amps @ 120vac it will need to pull 12.14 amps @ 12vdc.

Here's the calculator I used if you want to run the numbers yourself: https://www.batterystuff.com/kb/tool...-inverter.html

So, in the end my Vitrifrigo wins big time over a tiny little residential fridge. The Vitrifrigo uses only 5.5 amps @ 12vdc while the residential uses 12.14 amps @ 12vdc. And that was the smallest residential fridge I could online with current draw specs listed.

If you read threads where people can't figure out why their residential fridge won't run overnight on their batteries, this is the reason. They just looked at the amp draw and didn't do the calculations to convert from ac to dc. As voltage goes up, amps go down. The inverse is also true - when the voltage goes down (120 to 12) amps go up. The constant in the equation is watts - the unit will consume the same number of watts whether on ac or dc.

I've shown my work. Show how you come up with different numbers if you have a residential fridge that will run more efficiently than a Danfoss unit and which will draw less power.

[astrocamper]

I looked at the Nova Kool. I would prefer a locally available brand at a much lower cost plus not having to pay for shipping. Capacity difference of 9.1 vs 6.0 isn't worth that much to me. We did fine using our 6 cf Norcold plus our Engle freezer on a 12 day off grid trip last summer without needing to resupply.

I figure every fridge will eventually need replacement. I replace my home fridges about every 10 years. I would rather replace a 77 pound unit that cost less than a $1000 than a
105 pound unit that cost me close to $2000 every 10 years or so.

I just want one that cools down enough to use in few hours and keeps food cold on the hottest days.

[Itinerant1]

Enjoying the reading and others experience posted already.

Here is from my recoreded experience with a Norcold 821 over the past 3+ years with 1,280w solar & 500ah lfp continous boondocking. We almost pulled the trigger on a residential of equal size.

The Norcold was building up alot of ice on the evaporator fins and having to set the temperature on 6-8 (out of 10) all of the time. Something else that should be done but I'll bet most folks don't is pm the unit (maybe pull it out and check the exaust tube in back besides the burner).
I ordered and replaced the cooling unit ($655) myself with a new Amish unit which did help with cooling, settings now are 2-4 out of 10 "but" still was getting ice build up on the fins so added a 3 fan unit ($75) in front of the fins that can be ran all 3 at one time or 2 on/ 1off or 1 on/ 2 off and this has totally eliminated the ice/ frost build up on the fins now and most the time the settings now are 2-3. With the thermometer inside the fridge it will remain 34-40f range consistently. This is with travel from AZ to MT and various states/ elevations/ solar conditions in between.

With the amount of solar & lfp (quicker charging or psoc) During spring-summer-fall l'll switch the Norcold over from propane to electric (120vac) midmorning (8-10am +/-) till end of day (7-9pm) when solar is decreasing and the batteries are being depleted, on the display it will show 90-95% soc. The fridge will draw 28a when running, as been stated already if your solar/ battery bank isn't large enough it will be a losing battle for long periods of time. The system will generate 4-7 kwh of power daily depending on demands/ available solar.

Switching from propane to electric has also extended the 30# propane consumption time from 17-19 days to 23-25 days.

Before doing the Amish unit we did do homework on a residential style ($900-1000) 10.3 cu. ft. +/- that would fit in the same space with little to no alterations. Those units would draw roughly 120 -150ah daily and with my system it wouldn't be an issue during the spring-summer-fall but winter time we would either have to be more conservative (cut down on tv time in the shortest daylight periods) and still have to run a generator more often than we like. For our purpose the solar/ lfp was to eliminate the generator as much as possible.

It would be nice to have a slightly larger interior for more food storage when we get further out in the bush than what the Norcold offers.

I guess more homework is needed to be done on other manufacturers for when the time comes if we want to get rid of the Norcold, but it is nice having an option to be on propane or 120vac whenever you want while in the bush for long periods of time.

[astrocamper]

Today I added a vinyl glad cable to the eye hooks secured to existing brackets on the driver side of the trailer roof where the fridge is. The cable is secured high enough off the roof to keep from banging on the roof. I will use it to secure an Aluminet 70% sun blocking fabric using bungee balls all along the side of the trailer. I will use some 8 foot poles to hold it up away from the trailer and allow the air to ventilate underneath it. It will provide a 20 x 14 shading and help keep the sun on the trailer sidewall and fridge area. We go to 4-7 night astronomy events in open field with no shade so we can observe the stars. I like to keep my awning on the north side of the trailer for maximum daytime shading. The Aluminet sun shade will be on the hotter south side. The Aluminet allows the wind to pass through it so strong afternoon gusts won't be a problem.

I hope my fridge does better with the added shade.

[Itinerant1]

Sounds like a good plan. I believe it was Reed Cundiff that said it worked for him with good results for shading / cooling.

[Sweetbriar]

Originally Posted by richard5933

How do you figure that there is no power advantage of a DC fridge over a 120vac fridge? Our unit runs with less than 6 amps being pulled from the batteries. The most efficient 120vac fridges will pull 1-3 amps AC, and the inverter will have to pull 10-30 amps from the batteries to make that AC power.

There is indeed a difference. Otherwise, there would be no business model in which manufacturing the DC compressor fridge worked.

Use watts not amps. Watts is the measurement of energy consumed for a activity while amps are a measurement of potential. Watts will not change as you move between power type.

The DC fridge uses 520Wh/24 hrs or 86 watts per cu ft per day.
My 10 cu ft Magic Chef uses 831Wh/24 Hrs or 83 watts per cu ft per day.

The DC fridge cost $979 or $163 per cu ft.
My Magic Chef $348 or $34 per cu ft.

Where is the advantage?

[richard5933]

Cost of the unit is a totally separate conversation than efficiency. One may be willing to pay more for efficiency, or maybe not. I was. Sounds like you are not.

You can't only run the number of cu ft that you need. You've got to run the entire unit. You fridge is using far more power per day.

I did the testing by running the two loads and watching the amperage draw from the battery bank through the Victron monitor. Without a doubt, the Vitifrigo pulled less from the house batteries than even a 1 amp AC load going through the inverter.

[richard5933]

One other issue that plays into this is the loss going through the inverter. Most are only about 85% efficient.