DC frig selection advice

[cedric]

<br />I read on here that the compressor frig's are they way to go if you are boondocking on limited solar and batteries. I have found many models of the dometic branded as waeco.<br /><br />I am looking at this 18qt one for $431 +36 shipping<br /><a href="http://www.amazon.com/CF-018DC-COOL...colid=20OWP6T2J735P&amp;coliid=I2MFQLTLMRKOGM"><br />http://www.amazon.com/CF-018DC-COOL...colid=20OWP6T2J735P&amp;coliid=I2MFQLTLMRKOGM</a><br /><br />AND<br /><br />this 24qt one for $509.99 + 36 shipping<br /><br />Based on your experience are these too small for a week or two of food storage for one?<br />And from your experience are the prices fair?<br /><br />thanks<br />cedric<br /><br /><br /><br /><br />

 

[wrcsixeight]

I would find that unit too small, even if I preferred chest type vs front loading type.

I also find I Don't really pack 2 weeks worth of food in it, but buy food as I need it.

I would cut up a cardboard box to the fridge's dimensions and consider the ergonomics.

Will it fit nicely somewhere without sliding around while driving? How easy will it be to access where you store it vs where you are going to need to open it for preparing meals?

What about the power wire? The ciggy plugs wiggle loose all too often and too easily.

Hard to say if it will be big enough for you. Thefew times I used a chest type I found the loading and looking for items within had the lid off far longer than a front loading fridge.

Since there is not much price difference between model sizes, get something a little larger. They do not use that much more electricity, and It is a bummer if you cannot fit all the food inside you need, I'd get the smaller one only if a bigger one just would not fit without requiring redesign of the interior.

Danfoss compressor powered fridges should top your list.

 

[cedric]

thanks are these danfoss<span class="status_online" title="Online"><br /></span>

 

[wrcsixeight]

I spent 600$ with free shipping for my 51 litre front loading Vitrifrigo from here:

http://www.westyventures.com/parts.html#cart_restore

He can get the chest style fridges, even though they are not listed on his site.

You might be able to find chest style fridges as low as $375, but anything under 500 shipped is reasonable, as long as it is not the sawafuji compressor like engel/norcold. That thing is loud and vibrates up a storm,

 

[cedric]

thanks, that is valuable information. My friend had advised me that the chest type<br />might be better. His opinion was that when you open a small frig the small volume of cold air tends to spill out of the box. I'm not sure if this is true but I no the theory sounds good. <br /><br />I am looking at "ARB Fridge Freezer - 50 quart chest" for $600 shipped. It has the danfoss compressor that you mentioned and is both AC and DC.<br /><br />Ad states:<br />"The 50-quart model is able to maintain sub-freezing temperatures in 90 degree heat while only drawing 0.87 amps per hour from a 12-volt power source."<br /><br /><br />

 

[wrcsixeight]

The Chest style definitely have an advantage, because there is no seal at the bottom where it is coldest like a front loading fridge. <br /><br />&nbsp;But in terms of air spilling out when the door is open, I think the act of opening the top lid or the front door purges nearly the same percentage of cold air anyway. &nbsp;If all the items within are already cold, then the difference is negligible I bet.<br /><br />How efficiently the condenser's heat is removed directly effects the battery consumption. &nbsp;Most Danfoss powered fridges use forced air through the condenser with a 92 or 120mm computer fan, but some are passive and use no computer fan. NovaKool uses the passive approach with Danfoss compressor. Norcold and Engle use the passive condenser with the Sawafuji compressors. &nbsp;I believe all of the chest coolers have forced air on the condenser. &nbsp;Some use condensers that look passive and have a fan moving air around them. &nbsp;Some use condensers that look like car radiators that are designed for use with a fan.<br />Here you see the latter type:<br />

<br /><br /> Where you plan to store the fridge should sufficient ventilation so the fan does not recycle heat generated by the condenser and compressor, but pulls in cooler air and exhausts it. &nbsp;Fridges don't force things cold, they remove heat from things, and the condenser itself is where this heat is released to the atmosphere, so the more efficient this is accomplished, the less energy ultimately used.<br /><br />I found the fan noise was louder than the running of the Danfoss compressor itself.<br /><br />The 120mm &nbsp;fan which came with my fridge was rated at 72 CFM and was mounted to pull air through the condenser, and blow it onto the compressor and the then the electronic controller. &nbsp;Many other Danfoss powered fridges, even larger ones, come with 92 mm condenser fans rated at only 40 CFM and covering less of the condenser.<br /><br />I replaced the original 120mm 72 CFM fan with a 120mm 54 cfm fan(Noctua NF F-12), which has a very high static pressure rating, and pulls 1/2 the current of the original. &nbsp;I mounted it to push air through the condenser, &nbsp;and found it is significantly quieter in this orientation, and if anything, this location and this fan improved performance in terms of overall duty cycle.<br /><br />Danfoss compressor speeds can be increased for even faster cool downs. &nbsp;Mine came with a resistor in the thermostat circuit to run it at 2500 rpm as opposed to 2000 if removed. &nbsp;I removed it. &nbsp;Speeds upto 3500 are possible but most likely very overkill. &nbsp;It would probably overpower the evaporator(coldplate) of a smaller fridge.<br /><br />The slower the compressor runs to maintain sub 40 degrees and less than a 50% duty cycle the better the efficiency. &nbsp;I removed the resistor in mine and rarely exceed a 33% duty cycle to maintain sub 39 internal temps in upto 85 ambients.<br /><br />All these fridges with Danfoss compressors have &nbsp;slightly different coldplates, and condensers, and their own compressor speeds. &nbsp;Thus the different consumption ratings listed for similar size fridges with the same compressors. &nbsp;No doubt some sweet spot of compressor speed vs condenser size and fans speed exists, but many are optimised for certain functions, like faster &nbsp;compressor speeds for cool down time vs overall efficiency of a slower compressor speed. I think my fridge was running the compressor faster than needed. &nbsp;A faster compressor pulls more current, but runs for shorter periods.<br /><br />http://www.veco-na.com/images/Compr..._Guardian_and_Merlin_v2_with_pics_7.25.11.pdf<br /><br />http://coastalclimatecontrol.com/Me...;Product_Code=E51045&amp;Category_Code=access<br /><br />http://www.equipt1.com/Company Prod...l B Travel Box Test and Comparison Report.pdf<br /><br />http://www.rvworldstore.co.nz/blog/waecoengel/<br /><br />http://www.ra.danfoss.com/Technical...f_electronic_unit_ac-dc_04-2009_ei100g402.pdf<br /><br />Keep in mind how ambient temps in an enclosed Van will significantly increase duty cycle. &nbsp;Keeping the Van interior cooler means using less battery power, even considering the electricity used to move a fan.<br /><br />The air which cools my condenser is brought from the floor under the fridge by the condenser fan is pushed out a louvered vent behind the fridge with no chance to recycle preheated air.&nbsp;<br /><br />I've got an additional 3/4" to 1.5" of Foam board insulation all around the fridge, and made a Stainless steel &nbsp;cap/tunnel to protect the cooling unit from installation/removal stresses and funnel the air past the compressor and electronic controller with the help of a soft, heat resistant fan shroud.<br />

<br /><br />I've also installed a 40 mm interior fan rated at 0.03amps and 6.3 cfm. &nbsp;This allows faster cool downs of items placed within, more even temps throughout the box, and a lower setting on the dial. &nbsp;While this Fan won't necessarily reduce overall duty cycle or current pulled from battery.<br /><br />&nbsp;It Does allow me to faster cool down the fridge contents when I have a solar surplus, or am driving.<br />I can crank up the dial to 4 from 2(out of 7) and pull all the contents down to near freezing, then at night return the dial to 2, and use significantly less electricity overnight while the contents slowly rise back up to 38f. &nbsp;<br /><br />Isotherm fridges have an optional($$$) extra feature, an additional coldplate for storing extra energy when charging voltages are present. &nbsp;These units speed p the compressor to freeze the holding plate when charging voltages are present. &nbsp;I basically do the same thing manually but only with the thermostat, and store the energy in the colder Fridge contents, and the interior fan increases how effective this strategy is. &nbsp;I do think increasing the compressor speed during such times would be better. &nbsp;I got some ideas in the works for varying compressor speeds with the turn of a dial.<br /><br />I do have enough solar and battery power &nbsp;to not really &nbsp;concern myself about how efficient the fridge is, but insuring it is not working harder than it needs to is just in my blood.<br /><br />While the chest style fridges are probably slightly more efficient, I think their biggest advantage is portability.<br /><br />If portability is of no concern to you, your needs might be better met with a front loading fridge and efficiency can be likely matched and perhaps bettered with an insulated cabinet designed to evacuate condenser fan air.<br /><br />The Danfoss compressors are significantly less annoying than the buzz of a Sawafuji, but in a Van, in a quiet atmosphere, the noise can be bothersome. &nbsp;Design it so the compressor is not right next to where you plan to put your head when sleeping<br /><br /><br /><br /><br /><br /><br /><br />

 

[HoboBerg]

thanks, that is valuable information. My friend had advised me that the chest type&lt;br /&gt;might be better. His opinion was that when you open a small frig the small volume of cold air tends to spill out of the box. I'm not sure if this is true but I no the theory sounds good. &lt;br /&gt;&lt;br /&gt;I am looking at "ARB Fridge Freezer - 50 quart chest" for $600 shipped. It has the danfoss compressor that you mentioned and is both AC and DC.&lt;br /&gt;&lt;br /&gt;Ad states:&lt;br /&gt;"The 50-quart model is able to maintain sub-freezing temperatures in 90 degree heat while only drawing 0.87 amps per hour from a 12-volt power source."&lt;br /&gt;&lt;br /&gt;&lt;br /&gt;

I have had the ARB fridge for over 2 years now, and love it. Its the 50 quart model or 47 Liter as its marked,I find there is plenty a room in there can stay out for 3 weeks pretty easily. You can hardly hear this thing when it is running, and its kept all my food and beverages right at 32 degrees flawlessly. The fridgeis mounted under my bed on a the sliding platform works great, and also pulls right out in front of where I sit to double as a table. Definitely shop around I found looks like there about a $200 price difference on some of these websites. Hope this helps. If you have any questions feel free to ask.

 

[Willy]

I usually have my Waeco chest style unit set to freeze solid anything in the main (large) chamber, while the small one has milk 'n stuff. I generally buy a whole pile of family packs of meat, portion it out, and freeze it all solid. ..Willy.

 

[cedric]

This is fantastic information! thanks so much, ced

 

[karl]

Ced- do you mind sharing where you found the 50 qt ARB for 600? All the sites I find are 7+.<br />thanks

 

[cedric]

Ya, it was on Amazon but now it is somewhere between amazon's warehouse and mine .<br /><br />They had one left at that price in their deals warehouse. The packaging was damaged and they couldn't sell it as new so I got a deal. The rest are $795 I believe. Keep an eye on Amazon because I know they go through inventory like crazy. If they find another one in the warehouse with damaged packaging it will end up in their Deals Warehouse at a huge discount. Their deals all carry the new warranty and they treat returns the same. ANYTHING sold by Amazon is returnable. Be careful though if it is sold by a 3rd party through amazon you may not be able to return it.

 

[wrcsixeight]

Nice Find!<br /><br />The Danfoss controllers with the 120v AC option usually add 75 to 100$ more to the price of a fridge. My battery chargers basically take over the function when I have AC power available, But I am looking to get a RV converter which is basically a heavy duty battery charger that does not get confused with cycling loads.<br /><br />The Danfoss compressors are sensitive to voltage drop on their wiring when running on DC. &nbsp;The compressor will kick on for a second or 2 then shut off with the condenser fan still running. This has happened to me when I was using distant power outlets while working on the fridge cabinet. &nbsp;Too much voltage drop.<br /><br />To eliminate this, the Ciggy plug should be wired &nbsp;to the battery with thicker wire. &nbsp;The wiring should not be shared with any other devices. &nbsp;It is best if the wiring runs right to the battery rather than a shared buss stud or fuse panel. &nbsp;I ran a separate lead to my house batteries with a fuse right at the battery, bypassing my regular fuse block.<br /><br />The generic Ciggy plug receptacle can be improved upon as well.<br /><br />These ones have ridges inside to keep the plug from working its way loose:<br /><br />http://www.amazon.com/Marine-Grade-Cigarette-Lighter-Socket/dp/B0002KRC5Y<br /><br />A fridge makes Van dwelling so much nicer, you are going to love it.

 

[cedric]

Hi, that amazon link is not working. Is pretty much the same item. thanks<br /><a href="http://www.amazon.com/Marine-Grade-...eywords=Marine-Grade-Cigarette-Lighter-Socket"><br />http://www.amazon.com/Marine-Grade-...eywords=Marine-Grade-Cigarette-Lighter-Socket</a>

 

[wrcsixeight]

Both links work for me, and show the same product.<br /><br />I'd be interested to see if ARB supplied a resistor in the thermostat circuit, and what size and CFM fan they attached to the condenser, if it is easy to check or snap a photo of.<br /><br />My 270 ohm( for 2500 rpm) looked like this, mounted right to the controller:<br /><br />

<br /><br />

<br /><br />But ARB would likely use a different Thermostat and might choose to locate a resistor elsewhere.<br /><br />It's neat that one can 'fine tune' these cooling units with better fans and different compressor speeds to "Dial it in" for one application.<br /><br />Not necessary, but say if the fridge compressor speed is dialed high from ARB for quick cool downs, but &nbsp;then if the fridge is used 24/7, then slower compressor speeds could easily maintain sub 40f &nbsp;box temps and use less battery power to do so.<br /><br />If it came with no resistor, and one only turned the fridge on every now and then to cool down a case and a half of warm beer, then a resistor inline on the T stat circuit to speed up the compressor would significantly decrease the amount of time it would take to suck all the heat out of that warm beer.<br /><br />The Fan I installed uses half the electricity and makes half the noise for no loss of efficacy.<br /><br /><br />

 

[cedric]

I am not sure what is the resistor in your photo but if I can find something similar to your photo I will snap a picture and post it.

 

[wrcsixeight]

Sweet.<br />In my previous post, the photo shows the back of a Danfoss compressor controller. &nbsp;Yours will be very similar to this but have two more inputs on top for 120v AC.<br /><br />The Thicker pair of Brown and Blue wires go to the thermostat dial inside my fridge. Attached to this is a thermistor which clips to the cold plate.<br /><br />The Thinner pair of brown and blue wires are for the LED light inside my fridge. &nbsp;Whenever the fridge is plugged into 12 volts, this light will work when the door is opened. &nbsp;I took power from this light for my internal fan.<br /><br />The Thicker 12 awg red and black wires are the 12V DC input. Recommended the (+) red wire run straight to the battery, fused as close to the battery as possible. The black wire right to the (-) &nbsp;battery stud as well. Yours will have a ciggy plug attached to these terminals. &nbsp;Which is why I recommended a Good quality receptacle wired directly to the house battery and not relying on an existing ciggy plug receptacle which shares it's power with many other devices and connectors. &nbsp;These compressors are quiet enough that you might not notice the compressor cycling on then off really quickly due to inadequate wiring failing to support the inrush current to get the compressor moving.<br /><br />The thinner Red and Black wires run to the &nbsp;12 volt condenser fan. 0.5amp max. &nbsp;One could use this 12v output to trigger a common 30 amp relay if a fan more powerful &nbsp;than 0.5Amp fan is desired. Or some other device activated when the compressor is running, like flashing lights and a siren. haha&nbsp;<br /><br />The 270 ohm resistor itself it mounted on the green circuit board. .<br /><br />

<br />&nbsp;I removed &nbsp;the circuit board, and now that blue wire plugs directly into the controller. &nbsp;The reduction in compressor speed from 2500 to 2000RPM also reduces current consumed while it is running from ~3.2 amps to ~2.5 amps. &nbsp;It starts higher when the compressor kicks on and tapers downward toward the end of the cycle, that's why the ~ approximation.<br /><br />There are other terminals on the back of the controller. &nbsp;These allow one to fine tune the low voltage setpoints. <br />Another possibility is wiring up a LED light for diagnostics. &nbsp;It will flash trouble codes if they exist.<br /><br />How accessible the whole cooling unit is on the ARB is unknown to me.<br /> &nbsp;The controller can be mounted remotely from the compressor as well, but I think this is unlikely.<br />How interested you are in all this is unknown too, but the info is there is you want it.