Author Topic: Opinions on true 12v fridges  (Read 6679 times)

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dnix71

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Opinions on true 12v fridges
« on: November 04, 2014, 08:06:19 AM »
I've had an Engel 40 with the swing arm compressor for over 5 years with no issues. It used to be they were the only real choice to a thermoelectric cooler unless you had an inverter and ran a common household fridge. Lately there have been a lot of players enter the market.

This is a short list of off-grid battery/solar panel powered fridge makers I have seen listed on the web.
ARB
National Luna
Engel
Waeco
Danfoss
Norcold
Trailblaza
Dometic
Autofridge
Bushman
Evacool
Whynter

Does anyone here have a fridge on this list or like to add to the list and offer some opinions on the fridge they have personal experience with.

Thermo coolers are excluded from this list because they don't have thermostats (except for a few high-end Koolatrons) and can't maintain fish meat or dairy at safe temps.

Bruce S

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Re: Opinions on true 12v fridges
« Reply #1 on: November 04, 2014, 11:10:59 AM »
dnix71;
I cannot add anything to the list, but I'm curious about them and would like to see the biz end of one.
Bruce S
 
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mab

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Re: Opinions on true 12v fridges
« Reply #2 on: November 04, 2014, 03:21:17 PM »
a few years ago I lived on a boat and installed a new danfoss (at least that was the name on the compressor) 12/24v compressor fridge into a homemade coolbox built into the galley. It wasn't cheap at ~£300 but it worked very well, drawing just 3.5A at 12v and getting the cold plate cold very quickly, so not having to run for long (perhaps running for 3-5 mins before turning off depending on fridge loading IIRC). I sold the boat so I no longer have that fridge.

I actually have still an old Danfoss 12v compressor fridge which was thrown out by another boat owner; it's 12v only and pulls a good 5A and is a lot less efficient that the new one on the boat was (probably needs re-gassing, and that's probably why it was thrown out), but it still works, and based on my peltier experiments, is still more energy efficient than a peltier cooler would be.

Though I actually use a 230v fridge & freezer now via an inverter.

dnix71

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« Last Edit: November 04, 2014, 07:10:43 PM by dnix71 »

southpaw

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Re: Opinions on true 12v fridges
« Reply #4 on: November 05, 2014, 09:29:15 AM »
I have a 12/24v 5cu. ft. Sundanzer chest type fridge on my houseboat and have been using it for 5 years. I turn it on in the spring and off in the fall. I spend between 1 and 4 months on the boat each summer.
 I have 3 12v 63watt panels and 6 220 ahr 6v batteries which run everything on the boat, I have no backup generator, and do my vacuuming and clothes washing when the sun is shining. All my lights and water pump are 12v. I use a 2000 w inverter for the vacuum and washing machine. Solar clothes dryer, (long rope).
I think the fridge is great, got rid of 2 4 cu ft. propane fridges and never regretted it. It takes a while to get used to the chest type fridge and I used to miss not having a freezer but have learned to live with it. 

kitestrings

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Re: Opinions on true 12v fridges
« Reply #5 on: November 12, 2014, 09:00:59 PM »
dnix71,

I'll add a few:

Novakool
Steca
Sunfrost
*Dometic

And a story to add... One of the first off-grid appliances that I ever bought was a Dometic refrigerator from an AE dealer (and there weren't many of them then) in ME named Peter Talmage, Talmage Engineering; nice fellow I'd gotten to know in my wind days.  It is 8 CF, like many RV units, but uses a Danfoss compressor instead of the less efficient, and more common "3-way" absorption units.

Anyhow, this frig is still with us.  It is now 30 years old.  Works like a champ.  A few years ago it acted a bit flakey and I thought it was going to die, so I tried contacting Dometic; still had the manual.  Well, they never made such a thing I was told fairly curtly, but I explain to a couple folks there that the thing said Dometic RM760 front and center.  And, I had their manual in my hand.

Eventually I spoke to a guy who'd been there too long I suspect.  He explained, that they were actually labeled by Dometic under a contract for Winnebago, but manufactured by a company called Novakool.  Sure enough I called Noakool out in BC, CA.  They shipped me a new controller and we were back in cold beer.  And, our off-grid home had a new-found Winnebago prestige ;D.

We since have bought a Steca PF166 chest freezer.  There's an REView (remember those, when it weren't so glossy) in Home Power, issue 130, 2009.  Works great more refined than SunDanzer IMO, but hard to find/find sources for.

I also did some metering and data gathering on some of the Sunfrost units ~15+ years ago thru a DSM program.  Very efficient - same Danfoss compressor, thick walls, top-mounted coils - but very expensive.

Most of the newer Danfoss units will run on 12 or 24V, and Novakool I believe will do 48V units IIRC.

~kitestrings
« Last Edit: November 12, 2014, 09:05:10 PM by kitestrings »

dnix71

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Re: Opinions on true 12v fridges
« Reply #6 on: November 13, 2014, 08:44:32 PM »
http://www.sawafuji.co.jp/english/tech/shindou.html Here is a clear description of Engel's swing motor compressor. Thes piston is spring loaded and the coil around it is pulsed to resonate. No locked rotor amp issue.

kitestrings

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Re: Opinions on true 12v fridges
« Reply #7 on: November 20, 2014, 01:04:47 PM »
Interesting design.

I'm a little surprise that no one has figured out a way to do a mini-split, VSD unit for colder climates.  I guess it just complicates an otherwise pretty simple, extremely durable existing model (with it's associated mainstream appeal).  Still it always seemed crazy to me to be pulling 70 degF air from my kitchen to cool food when its 20 degF outside.

I'd always thought it might be logical to have a ducted air system that allowed you to choose from in indoor to outdoor air stream based on temperature.  On commercial units they often go after this with split, balance port compressors, or "economizers" that take in outside air (temperature and humidity allowing).

~ks