DC fridge freezer as a freezer

[Kartman35]

I am wondering how effective these things are at truly maintaining freezing temperatures. Read lots of threads on power consumption at 3-4 C but little much below that.

My plan is to freeze some icepacks, meat and ice cream at home, and keep it frozen in the freezer running off of a group 27 90AH battery with 175 minutes RC @25A. I will be fishing/camping, so I'd like to use a cooler as a fridge and rotate ice packs from the cooler to the freezer, and freeze my catch to bring home. I'll have a 1600W inverter generator that I plan to run during the day from noonish 'till around 4:30 to recharge my trolling motor batteries so I'll charge my fridge battery at the same time while running the fridge off of AC. I have a 10 amp battery charger I can use for the fridge, but may consider a more powerful one if necessary.

So, will my ice cream still be hard after a week? I'm in Canada, so the nights are cool enough and the hottest part of the day will be run on AC. Is my battery big enough to maintain freezer temps for 19-20 hours a day with 4-5 hours recharge at 10A?

The models I'm considering are Indel B/Truckfridge 55, Dometic cf50/Novakool, Engel MT45. Any one of these better suited to my application than the others? I suppose if I got one that has that 'warmer zone' above the compressor I'd just fill it with insulation...don't want a warmer zone warming my freezer....

Any input much appreciated

 

[moodywizard]

I think charging the battery for 4 hours a day will be more than enough. The fridges only draw a few amps, and that's when they are running. I have a ARB 50 and just began using it as a freezer, it is really efficient.

 

[4x4junkie]

I don't think you will be happy with the performance of a 12v unit refreezing icepacks for a cooler, they just don't have the capacity to cool icepacks down in any reasonable length of time (they do fine maintaining freezing temps, they just take a long time to get there, especially if non-frozen items are present).

If you have to have a freezer, I would suggest maybe have two units, with the other one operating at fridge temperature.
Another option (since you'll have your generator going) might be one of those standalone icemakers you can get for around $150 or so. Supposedly they'll make a batch of ice in a few minutes to a half hour, which you could then use in your cooler (or put into the freezer overnight and use the next day).

 

[Kartman35]

Oh well

Thanks for the help. I'll also look into that ice maker idea.

Maybe something like this would work???

http://www.solartown.com/store/product/sundanzer-dcf50-solar-freezer-2/#null;

 

[Scott H Murray]

I went on a fishing trip, the outside temp was getting to 40deg Celcius and I had my fridge set at freeze (-15deg C). And the fridge (Engel 60 litre) ran for a week, but I did have to drive a bit or leave the car running but it froze a full fridge of fillets that we had caught. I would definitely recommend a dedicated battery just for the fridge and one of those dc to dc chargers that you can now get.

 

[Kartman35]

Are you sure???

I just read this review on amazon for the Engel MT45:




5.0 out of 5 stars Fridge/Freezer, May 29, 2012
By Paul V. Lippincott (Newport, NC) - See all my reviews
(REAL NAME)
Verified Purchase(What's this?)
This review is from: Engel MT45F-U1 Dual Voltage AC/DC Portable Fridge/Freezer 43 Qt.
I have used a Koolatron cooler for a number of years in my truck. It just barely keep items cool. My first week in the truck I set the thermostat to three and it froze everything solid. I now run the thermostat at one, and everything is nice and cold. The fridge does not draw that much electric. I have a 12 volt cut off switch and after a weekend the fridge is still running. The old Koolatron would kill my batteries in 24 hours. I am very pleased with my new fridge. It is a bit pricey but hopefully it will be worth it.

They go to five...

 

[Kartman35]

I went on a fishing trip, the outside temp was getting to 40deg Celcius and I had my fridge set at freeze (-15deg C). And the fridge (Engel 60 litre) ran for a week, but I did have to drive a bit or leave the car running but it froze a full fridge of fillets that we had caught. I would definitely recommend a dedicated battery just for the fridge and one of those dc to dc chargers that you can now get.

didn't see that when i last posted...thanks that's encouraging

 

[IdaSHO]

I know my Dometic/Waeco DC marine fridge will make ice in the fridge portion if set low enough.

We have it set to maintain 40 degrees in the fridge compartment, and it still makes ice in the freezer compartment.

All while only drawing a few amps.

 

[4x4junkie]

I just read this review on amazon for the Engel MT45:

...

Oh don't get me wrong, they'll definitely freeze stuff solid for sure, I was referring to the speed at which it freezes. If your icepacks are small (or you only need them for every other day), it'll probably work fine (though it will be running a lot). Figure the freezing speed of a 12V unit is about ¼ of what a typical household unit is capable of.

 

[Ziv]

4x4junkie said, “the freezing speed of a 12V unit is about ¼ of what a typical household unit is capable of.”

If two containers maintain a temperature of 0°, it doesn't matter whether the compressor is run by 12v DC or 110v AC, … if the temps remain the same, a unit of water will freeze at the same rate.
My 12v Edgestar will freeze a liter of water at the same rate as my 110v household Whirlpool.
0° is 0°; it doesn't matter whether it comes from 12v compressor or your ex-wife's heart.

 

[Kartman35]

0° is 0°; it doesn't matter whether it comes from 12v compressor or your ex-wife's heart.

That's awesome...I really hadn't considered that...maybe I should just cut my-exes heart out and bring it camping....

Seriously though, I found a ridiculous deal on an Engel fridge freezer MD14F for $100CDN!!<---edit should mention it's used...
I know it won't hold much, but I'd pay more in taxes than that on the purchase of a new model.

I'm going to pick it up on Thursday and do some torture testing to see how fast it'll freeze stuff, and how long my battery will power it on full freeze.
I'll report back with my findings as they come in.

Thanks for the help, all input much appreciated

 

[Ziv]

Just remember, a good battery and recharge system is the key to these 12v fridge/freezers.

 

[WhileInTheWild]

I have the Whynter 45qt that is supposed to be good for a hard freeze down to -8F but I've only used it as a fridge so far, I hook it up to a 100 amp hour battery that I hook up to a Renogy 100W solar panel to keep it charged, gives me pretty much freedom to stay out as long as I want.

 

[4x4junkie]

4x4junkie said, “the freezing speed of a 12V unit is about ¼ of what a typical household unit is capable of.”

If two containers maintain a temperature of 0°, it doesn't matter whether the compressor is run by 12v DC or 110v AC, … if the temps remain the same, a unit of water will freeze at the same rate.
My 12v Edgestar will freeze a liter of water at the same rate as my 110v household Whirlpool.
0° is 0°; it doesn't matter whether it comes from 12v compressor or your ex-wife's heart.

Perhaps you should go try that then and get back to me. (really want to see a difference? Use several 2-liter bottles of water)

Physics is physics.... Heat given off by a warm mass (especially water due to it's very high latent heat characteristic) placed into a space refrigerated to 0°F WILL cause the temperature in that space to rise if the heat given off exceeds the capacity of the refrigeration system removing it. A small 40-50 watt refrigeration system is not going to remove heat from that space (and the mass placed within it) at the same rate as the 150-200 watt system in a household unit can.

 

[highdesertranger]

well what I know is my engels freeze better and faster than my home freezers especially if there is a lot of frozen stuff in there already. 4x4junkie are you taking into account the cubic area of the box size. sure the home unit is more powerful, but it must cool down a much larger area. I have found that if all things are equal like both filled to 50% capacity with frozen stuff then place a bottle of water in the engel will freeze it faster. this is of course turned down to the lowest setting, while the engel will run contentiously, the home unit doesn't. even turned down it still cycles. highdesertranger