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 > AC/DC Compressor Refrigerators

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prichardson

Lafayette, La

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Posted: 01/12/19 08:32am Link  |  Quote  |  Print  |  Notify Moderator

About the only real advantage of a compressor type refrigerator in the RV world is that it has a quicker recovery time. From my experience in the marine world; when operating on 12VDC these units draw 5 to 7 amps when running and a duty cycle of about 50% (ie will be running 12 out of 24 hours).

Lwiddis

Monterey, California

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Posted: 01/12/19 08:37am Link  |  Quote  |  Print  |  Notify Moderator

Regular use of a generator when you have a solar system is a “fail” for your solar system.


2015 Winnebago 2101DS TT & Tahoe LTZ, 300 watts WindyNation solar-parallel & MPPT, Trojan T-125s. TALL flagpole for US flag. Prefer USFS, COE, BLM, NPS, TVA, USF&WS, state & county camps. Bicyclist! 14 year Army vet - 11B40 then 11A - old MOS 1542 & 1560.


CA Traveler

The Western States

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Posted: 01/12/19 08:57am Link  |  Quote  |  Print  |  Notify Moderator

The amps in the posted link are rather limited and inconsistent. What is needed for a RV that is off grid is the power usage as in Ah or KWh. ie 0.9A AC for how long or say average KWh per day or year. That information is available for popular residential refers.

The AC power is 108W, 12V is 42W and 24V is 53W. This suggests that the AC power is rather inefficient, but when plugged in most would not care.

42W is reasonable but for how many hours a day is the critical missing information?

This unit may be efficient and a viable option for it's size but the information to determine this is lacking.

With 220Ah batteries at 12V the refer would run for 31 hours before reaching 50% SOC. If the cycle time is 25% then it's good for 5+ days. ie For fully charged batteries and no other loads.

Quote:

Amps: 0.9 at 120V AC; 3.5 @ 12V DC; 2.2 @ 24V DC.



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theoldwizard1

SE MI

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Posted: 01/12/19 10:21am Link  |  Quote  |  Print  |  Notify Moderator

prichardson wrote:

About the only real advantage of a compressor type refrigerator in the RV world is that it has a quicker recovery time.

Compressor based refrigeration provides a much more consistent internal temperature over a wide range of ambient temperatures.

theoldwizard1

SE MI

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Posted: 01/12/19 10:30am Link  |  Quote  |  Print  |  Notify Moderator

CA Traveler wrote:

The AC power is 108W, 12V is 42W and 24V is 53W. This suggests that the AC power is rather inefficient, but when plugged in most would not care.

Concur !

As mentioned previously, most of these use a Danfoss compressor (the company has been bought and sold a couple of times in the past 10 or so years so I don't know if that brand name is still used) and when running on AC actually use a converter to generate the 12/24VDC (which is more interesting as the DC is actually converted to a variable frequency 3 phase AC current !) This suggests that maybe you should a better 12VDC converter (power supply).

If I boondocked a lot, I would have an invert/charger/transfer switch and I would just leave the refrigerator connected to DC power, via an appropriate fuse.

BoonHauler

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Posted: 01/12/19 11:08am Link  |  Quote  |  Print  |  Notify Moderator

3 tons wrote:

mobeewan wrote:

I've been looking at Novakool. They make Marine refridgerators and freezers that can run on 12v or 24v. One similar in size to the Norcold is only a couple hundred dollars or so more expensive, but they are proven units used in boats. I've seen a couple YouTube videos were people built their own campervans from scratch and installed Novakool units. They also had solar panels installed on the roofs with about 400 to 600 watts of battery.

Since I plan on using solar in the future and building a camper van or enclosed 16 foot utility trailer/camper with 800 to 1000 watts of solar I'll probably go one of 2 routes. One is a large Domestic chest refridgerators/freezer in freezer only mode and a dorm fridge. The other route is a tall Novakool with freezer on the bottom and if needed a small dometic chest freezer/fridge I can fire up if I needed a little extra freezer space.

If I stick with just my 28 ft TT I am considering adding solar any way. I might also replace my weak Norcold with a Novakool.


For the Novakool RFU 6800 they list the amps at 5.2 @12v, so a sufficient of solar to augment makes perfect sense.


I have a Nova Kool 6 cuft refrigerator and 6 cuft freezer and love them! .... they work great! Way better than absorption units!

A 50% duty cycle is a good number to use as prichardson mentioned.

I dry-camp 100% of the time, a properly sized solar system is the only way to roll ..... =)


05 RAM 3500 CTD 4x4 Q/C Laramie DRW/NV5600/3.73, B&W Gooseneck, MaxBrake, PacBrake PRXB, Brite Box Fogster, BD steering Box Brace
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crosscheck

Coldstream, BC

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Posted: 01/12/19 11:10am Link  |  Quote  |  Print  |  Notify Moderator

From 2011 to 2016, we had a NovaKool 7500 fridge/freezer AC/DC unit in our TC. 95% of our camping was dry. Had a generator and used it maybe three times. Our RV electrical usage was moderate, had 330W solar and 4 6V AGM batteries. Pros and Cons as followed:

Pros:
1) Can be out of level for indefinate amounts of time which suited our camping style(boondocking)
2)Used 1/3 less energy( not electricity), than absorption fridge which unless you are trying to save the world, not a big issue.
3) Outside measurements for a Compressor unit is 1/3 less for the same interior volume as an absorption unit. A 9cuft NovaKool will fit in the same spot as Our pressent 6 cuft Norcold propane fridge.
4) Freezer has frost forming on walls 20 minutes after start up.
5) More consistant inside temperatures especially in hotter weather.
6) Never heard of a compressor unit catching fire and there must be many 100,000,000 of units throughout the world.
7) Many of the places we camp in northern BC, do not have available propane fill ups and as we use propane for cooking, hot water, heat, BBQ, you do not want to run out of propane.
8) Our unit pulled 4.4A when cycling as per amp meter.(60W)

Cons:
1) You can hear the compressor(quiet), while the absorbsion units are dead quiet.
2) 200W of solar and 2 batteries minimum alone for the fridge is required.

We are satisfied with the 6cuft Norcold in our TT, but if it ever failed, I would replace it with a 9cuft NovaKool as we already have 490W solar and 4 6V GC2's.

Dave


2016 F350 Diesel 4X4 CC SRW SB,
2016 Creekside 23RKS, 490W solar, 2000W Xantrex Freedom 2012 inverter, 4 6V GC-2 (450AH)
2006 F350 CC 4X4 sold
2011 Outfitter 9.5' sold
Some Of Our Fun:http://daveincoldstream.blogspot.ca/

bob_nestor

murphy

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Posted: 01/12/19 11:29am Link  |  Quote  |  Print  |  Notify Moderator

When I looked into this a couple of years ago the most efficient (in terms of power consumption) were the EvaKool units built by an Australian company for RVs (Caravans) used in the Outback. Unfortunately I couldn't find any way of getting one imported into the US.

EvaKool

I do a lot of dry camping and opted for a portable Engle 12/1220v refer/freezer that seems to have the lowest power consumption for portables. Even so, with my 300w of solar and two 12v Lithium Ion 125ah batteries I can only go about 3-4 days before having to top off the batteries with the generator.

jplante4

Cape Cod

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Posted: 01/12/19 11:41am Link  |  Quote  |  Print  |  Notify Moderator

gemsworld wrote:

jplante4 wrote:

We have the new Dometic AC/DC compressor in the store. When we first got it we hooked it up to a group 27 12v battery and it ran for 40 hours before the battery got down to 10.7 volts. Then we plugged it in and watched the temp. It stayed constant until the whole thing stopped working in 2 months time.


Are you saying the fridge stopped working as in it failed after being used for only two months? If so, what was the cause of the failure?


Yes it failed. I believe it was one of the first ones produced for Dometic and may have been a floor model. See my comment in the Prevost vs. Newmar post in class A forum about the quality of newer appliances.

We just got the replacement and have not sent the failed unit back yet, so I don't now the cause.


Jerry & Jeanne
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Ivylog

Blairsville, GA and WPB, FL.

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Posted: 01/12/19 12:41pm Link  |  Quote  |  Print  |  Notify Moderator

My EnergyStar Whirlpool 21 cuft draws 9 amps DC measure before the inverter...96 Watts. Its duty cycle is 40-45% confirmed with a KW meter...1.2-1.3 KW/day. 3X the size on 50% more power and half the price of DC powered units. Not a hard decision.


This post is my opinion (free advice). It is not intended to influence anyone's judgment nor do I advocate anyone do what I propose.

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Sold 04 Dynasty after 14 great years.
How I tow.
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How I spend the winter.

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