We have received our 12 VDC refrigerator that will be used in out cargo trailer conversion. It occurred to me that this would be a great refrigerator for a fixed off grid location as well as a mobile one. It uses a Secor, formerly Danfoss, compressor unit. Runs on 12 VDC or 24 VDC. 4.2 cu ft interior capacity, so about half the size of the Servel propane fridge we have in the cabin.
I plan on adding 2 inches of XPS foam to both sides, under it, on top and behind. Maybe more behind against the exterior wall and more on top. With 2 inches extra a very similar fridge, the Novacool, can use as little as 240 watt/hours a day (@70 degrees environmental temperature).
Photos...
(https://i139.photobucket.com/albums/q305/djmbucket/Cargo%20Trailer%20Conversion/fridgeampbox.jpg) (https://s139.photobucket.com/user/djmbucket/media/Cargo%20Trailer%20Conversion/fridgeampbox.jpg.html)
(https://i139.photobucket.com/albums/q305/djmbucket/Cargo%20Trailer%20Conversion/fridgedooropen.jpg) (https://s139.photobucket.com/user/djmbucket/media/Cargo%20Trailer%20Conversion/fridgedooropen.jpg.html)
(https://i139.photobucket.com/albums/q305/djmbucket/Cargo%20Trailer%20Conversion/fridgeinterior.jpg) (https://s139.photobucket.com/user/djmbucket/media/Cargo%20Trailer%20Conversion/fridgeinterior.jpg.html)
(https://i139.photobucket.com/albums/q305/djmbucket/Cargo%20Trailer%20Conversion/compressor-01.jpg) (https://s139.photobucket.com/user/djmbucket/media/Cargo%20Trailer%20Conversion/compressor-01.jpg.html)
(https://i139.photobucket.com/albums/q305/djmbucket/Cargo%20Trailer%20Conversion/compressor-02.jpg) (https://s139.photobucket.com/user/djmbucket/media/Cargo%20Trailer%20Conversion/compressor-02.jpg.html)
(https://i139.photobucket.com/albums/q305/djmbucket/Cargo%20Trailer%20Conversion/icecubetray.jpg) (https://s139.photobucket.com/user/djmbucket/media/Cargo%20Trailer%20Conversion/icecubetray.jpg.html)
It is a "Truckfridge", model TF130. $599 + shipping $100
Nice! Do you have a thread on your cargo trailer conversion? I've always wanted to do that but never had enough money, know how or patience.
There is a thread. http://countryplans.com/smf/index.php?topic=12455.msg161753#msg161753 It has a false start and then long silence and a new start. Within the next week our CT should arrive. It is supposed to be on a truck from TX now. When it is in I will start a brand new thread.
Hi Don,
What is meant by "70 deg enviromental temperature"? Does this mean that it wont
work if it is much different from 70 deg, or just very poorly. I would think that if it was made for trucks you would get a large spread of temperatures.
Sorry for being confusing.... I mean that it uses that much power when the temperature of the space where it is located is 70 F. If it gets warmer it will run more and use more power; if it gets cooler in the space/room it will run less, use fewer watts.
That makes sense. A while back I read something either here or on
steelsoldiers.com that was discussing refrigerators and it was saying that
the newer refrigerators depended on being indoors to run properly, as
oposed to being kept in the garage so I thought you were refering to that.
Thanks for the quick response!
What is the panel/ cable/ charge controller/ battery rig you will be using to power this?
Or is it batteries charged of the car electrical system?
I think I saw the cargo trailer in one of your other pictures. I have a chance to buy a 7'X12' Wells Cargo for $1,800 or jew down price maybe $1,500. I would really like to have it but right now I have too much on my plate. I know I will kick myself later. d*
Yes you will John! Very good price.
I did post a floor plan in the other thread. No photo of the actual trailer yet.
Quote from: hpinson on January 17, 2014, 09:17:19 AM
What is the panel/ cable/ charge controller/ battery rig you will be using to power this?
Or is it batteries charged of the car electrical system?
To begin with it'll be off the truck charge with an isolator relay. Two golf cart batteries. Also a Yamaha 2000i inverter generator and an Iota charger that I have laying around un-used. Then a panel(s) at some point; MPPT controller like the Rogue MPT-2024. ???
I was reading the compact fridges used in dorm rooms and such are very power inefficient. It went on to say those fridges use the sides of the cabinet to dissipate heat. Insulating those sides would be bad I think. It looks like yours has access to the exchange coils that you would not insulate.
Right, the typical dorm fridge is notoriously inefficient in its electrical use. Many of those, just like many modern home refrigerators and freezers have theor condenser units under the metal skin. This refrigerator is not your typical dorm fridge. It does not have anything under the skin other than insulation and a cold interior space.
That black "thing" on the upper right rear corner is the compressor, the control box and the condenser, all in a neat little space. The evaporator is inside as a part of the freezer chamber, like a typical old fashioned single door upright with freezer. The SECOP compressor was known as the Danfoss compressor for many many years. It is the most efficient true compressor used in refrigeration. There are many makers using them. They are not cheap like the Peltier effect thermoelectric dorm fridges. Adding extra insulation to sidewalls, rear, top, bottom or door is fine with the caveat that the compressor / condenser area must have a free flow of air, to and from. The unit has a fan that operates whenever the thermostat starts the compressor. Hope that clears that up.
I edited the last reply of mine, I made a misstatement.
The cooling fan is situated to the rear. It moves air from the back of the fridge, thru the condenser portion at the rear, over the compressor and the control module then out the side. So I have to figure how to best baffle and channel the air flow out the trailer wall. I don't want to simply circulate the hot air from the compressor / condenser into the trailer interior. Not in warm weather anyhow. It would be nice to save that heat to the interior in cold weather though.
Maybe a vent with a diectional vane so that it goes outside in the summer and
inside in the winter. Don't they have mechanisims that are controlled by temperature
that could turn the vent vane? Just thinking out loud here.
I'm looking into the possibility of reversing the fan flow to be directed to the rear instead of the front and thus straight out a wall vent.
Then if that is good I'll see about a summer / winter thing. It's more important to me to push the heat from the condenser outside in summer, I think. ???
That makes sense. As for the vent to outside, you could just use a simple
manual operated vane. I think I was getting too fancy.
I got my DC amp/watt meter back and ran the fridge for a few days measuring the power used. The fridge was in a room that would run up to 74 -75 F during the day and cool off after 10 PM to a low of 65 F. The internal temperature of the fridge was 36 to 38 F.
The TF130 used an average of 350 watt hours in 24 hours. Or, another way to look at that, it used 26 amp-hours running off a nominal 12 VDC. At that rate a pair of 6 volt 220 amp-hour batteries in series would last slightly over 4 days, with a maximum discharge of 50%, with no recharging at. I figure that is pretty good.
With 2 inches of extra foam both sides, rear, top & bottom the TF should get better.
To save the heat to the interior in cold weather, you will be blowing inside air (70 degrees-ish) over the condenser to cool it. I wonder if keeping the heat in the trailer saves more energy than blowing cold outside air over the condenser, cooling it much more quickly, then sending the heat outside.
Cooling the condenser with cool outside air should use less of the precious electricity, with the lost heat being replaced with less-precious wood or propane.
I have no idea if using cold air to cool the condenser will screw up other parts of the refridgerator's cooling cycle.
From what I've seen on other forums, boats, etc, the Danfoss / Secop compressors do not seem to have a problem with cool / cold air being blown over the coils.
The whole thing of cooling with inside or outside venting is a big question mark. Is the effort to make a good switchable vent system worth the extra effort required? I have not definitively answered that yet myself. ???