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Old 13-07-2019, 08:33   #1
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12v refrigeration system for 11 sqft

Hi folks, I have rather large boxes (well insulated)
5.5 sqft freezer and 5.5 refrigerator.
I want to replace the A/C system with a DC system and it would be nice to have one system that was big enough for both.
I like the Cool Blue system but I am told that I would need 2 units for the size of my boxes because cool Blue handles up to 9sqft.
We plan on spending significant time in tropical waters so I definitely need to oversize vs undersize.
Thoughts on who might have a larger system that would fit my needs?
I have tons of solar and battery storage so I am covered there.
Scott
Brewer 44
Morro Bay Ca
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Old 13-07-2019, 08:50   #2
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12v refrigeration system for 11 sqft

I have a 14 cu spill over that is 50/50 freezer/ fridge.
I have a cool blue, Rich and I talked and he built me a BD80 powered one with dual cold plates.
He did tell me from the beginning that two individual systems would be better, but I didnít want to spend that much.
Itís marginal on mine, but I only have the original 32 yr old ice box insulation and that is Iím sure why itís marginal, if I had good insulation Iím sure it would have a much lower duty cycle. As it is now in the tropics if I maintain a hard freeze, the compressor runs nearly continuously, but it can maintain single digit temps in the freezer if needed.

Call Rich, he can advise, donít order without taking to him.

Insulation is I believe just as relevant or maybe even more so than box size, but almost no one knows really how good their insulation is, so a manufacturer has to assume average and go by box size when recommending a system.
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Old 13-07-2019, 10:08   #3
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Re: 12v refrigeration system for 11 sqft

Quote:
Originally Posted by wscotterwin View Post
Hi folks, I have rather large boxes (well insulated)
5.5 sqft freezer and 5.5 refrigerator.
I want to replace the A/C system with a DC system and it would be nice to have one system that was big enough for both.
I like the Cool Blue system but I am told that I would need 2 units for the size of my boxes because cool Blue handles up to 9sqft.
We plan on spending significant time in tropical waters so I definitely need to oversize vs undersize.
Thoughts on who might have a larger system that would fit my needs?
I have tons of solar and battery storage so I am covered there.
Scott
Brewer 44
Morro Bay Ca
When someone tells you their boat has a single Danfoss BD compressor that can handle a ten or larger cubic ft spillover refrigerator freezer always ask them for quantifying data based on there cruising latitudes. Spillover systems with only one compressor are generally poor performers do to temperature control problems. It is true cruising boats operated above Latitude 27N can get by with one half the daily energy. You should understand your 5.5 freezer will require twice the daily energy needed by same size refrigerator. Always ask those offering advice what size and source of all their 12 volt power. Large battery capacity is never a solution. Always ask what is their worst case daily power consumption including the other daily boat 12 volt use. Generally when a boat owner pushes the design envelope for refrigeration he later finds he needs a Honda portable generator.
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Old 13-07-2019, 19:11   #4
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12v refrigeration system for 11 sqft

So Richard dual compressors use less energy than a single larger one?The COP is better? Lower power consumption from dual 35ís over a single 80?
Or are you saying that saying that a 50/50 spilt over 10 cu ft is just too big for a boat?
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Old 13-07-2019, 19:16   #5
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Re: 12v refrigeration system for 11 sqft

Hi all and thanks. A64pilot, that's what I was thinking two.
Rich, how come no one uses anything bigger than the Danfoss?
Could I install one unit in my Freezer and use it as a spill over and then expand it later by adding the second unit in the refrigerator later?
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Old 13-07-2019, 19:29   #6
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12v refrigeration system for 11 sqft

Oh, and I have a kilowatt of Solar and also run an Engle as a deep freeze, keeping it below zero, itís duty cycle is almost continuous also.
Iíve never been further North than Brunswick Ga.
I use 130 AH overnight with both fridges / freezers running watching some TV with the satellite receiver and I will use a Honda in the morning, but thats not to make more power, but to extend charging hours to ensure my AGM bank is fully charged, Solar in the middle of Winter can easily replace the power, but I may not get a full 6+ hours of good Solar.
I keep the freezer low teens and the fridge low 30ís. Temp control has been perfect once I put a fan between the fridge and freezer and control it with a thermostat, before that it was a pain, add a case of beer or a coupe gallons of ice tea / lemonade or a watermelon and the fridge temp would rise as it wasnít controlled, it was passive.
I donít see as how running a Honda for less than an hour a day is any big deal myself.
Now if I had a Gel bank or of course a LifePo bank then I wouldnít need to run the Honda except to make water and wash clothes. We make water twice a week and that would ensure the bank gets to 100% fully charged of course as long as we did it early in the morning.
A kilowatt is good for on average of about 300+ AH per day.
like most people I have more Solar output than I can use by lunch, so we turn the inverter on and make ice with the counter top ice maker.
I donít know what my usage is during the day when Solar is more than meeting demands as I think the AH counter doesnít see the power that Solar is making and being used, but Iíd guess maybe 100, based on there is a whole lot less hours of Solar output than not in a 24 hour day, in Winter.
Summer Iím sure I wouldnít need to run the generator at all to charge, but itís too hot for me in Summer and Iím afraid of hurricanes, so I hide.
I have a 660 AH bank, but as Richard was I believe trying to say, a bank is just a storage medium. You have to make the power first to charge that bank, so a bigger bank wonít allow a bigger fridge, you need a charge source large enough to support it.
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Old 13-07-2019, 20:00   #7
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Re: 12v refrigeration system for 11 sqft

Quote:
Originally Posted by wscotterwin View Post
Hi all and thanks. A64pilot, that's what I was thinking two.
Rich, how come no one uses anything bigger than the Danfoss?
Could I install one unit in my Freezer and use it as a spill over and then expand it later by adding the second unit in the refrigerator later?


Peter Mackay at ozefridge@ozemail.com.au will be able and I believe willing to give you an opinion regarding your fridge questions.
They are designers and manufacturers of better quality refrigeration products across the marine, four wheel drive and challenging location environments, with a long and enviable track record. Australian produced but willing to provide guidance and advice without fear or favour, as I believe Rich Boren is also and somewhat closer to your location.
Cheers, hope this may help.
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Old 13-07-2019, 20:02   #8
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Re: 12v refrigeration system for 11 sqft

Rich Boren was I believe his next door neighbor, if he was in Morro bay a year or two ago.
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Old 13-07-2019, 20:52   #9
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Re: 12v refrigeration system for 11 sqft

I have about the same size fridge and freezer as you. I am pretty happy with the 12vdc system I purchased from Cleave at SeaFrost. One unit runs the freezer and I maintain -5 to 0 the other unit runs the fridge around 36-39. In San Diego now at anchor I use 85 amps over 24 hours. In Mexico during the summer I was using around 120. My box's are supper well insulated (arogel) which is the key.
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Old 13-07-2019, 21:26   #10
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Re: 12v refrigeration system for 11 sqft

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I have about the same size fridge and freezer as you. I am pretty happy with the 12vdc system I purchased from Cleave at SeaFrost. One unit runs the freezer and I maintain -5 to 0 the other unit runs the fridge around 36-39. In San Diego now at anchor I use 85 amps over 24 hours. In Mexico during the summer I was using around 120. My box's are supper well insulated (arogel) which is the key.
Yep, insulation is the key to any system trying to pump heat from one side to another to cool (or heat) one side.
I magine a pump in the middle of a creek - and you are spending money running that pump trying to reverse the flow of the creek.(Can't be a pond - entropy is real).
Pretty stupid.
Now build a dam across that creek - your pump might actually achieve something, especially if the pump is big and the dam doesn't leak.
For a leakey dam, you are going to need sa bigger pump and lots more fuel.
A great, low leakage dam - well, you will have to deal with the base water flow (entropy, remember) but you might get away with a pretty small pump with a low duty cycle.
Check your insulation first - that's the dam to heat flow. Then start figuring out pumps and duty cycles.
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Old 14-07-2019, 04:01   #11
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Re: 12v refrigeration system for 11 sqft

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So Richard dual compressors use less energy than a single larger one?The COP is better? Lower power consumption from dual 35ís over a single 80?
Or are you saying that saying that a 50/50 spilt over 10 cu ft is just too big for a boat?
You indirectly have made my points with your separate postings and no two BD35 compressors would not have the capacity to handle those dual boxes in a tropical climate. The BD 80 is a LBP ONLY compressor so it is less efficient in a duel temperature application. A BD50 for refrigerator box and a BD80 compor for freezer would be the correct application. Again if a boat stays above Latitude 27N daily energy consumes is much less. Still the major problem with 12 volt refrigeration on boats 35 to 50 foot is they normally lack the on board DC current generating power grid capabilities that you have. Don't you also have a generator and a portable Honda. The cost of 12volt refrigeration is only the small investment compared to the costs to support its daily direct current power grid.
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Old 14-07-2019, 04:31   #12
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Re: 12v refrigeration system for 11 sqft

FWIW I have a SeaFrost dual plate system cooling a 10-11 cf spillover freezer/fridge and it has no problems keeping steady temp of 38 degrees in the heat here this summer. It's been over 91 degrees here every single day since I got here five weeks ago.

That said, it uses a lot of juice. I have 540 watts solar and 420 amp hours. It's pretty much always sunny here and we're at peak solar season. I have not had to run my engine to charge yet but a few days have been close.
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Old 14-07-2019, 10:43   #13
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12v refrigeration system for 11 sqft

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You indirectly have made my points with your separate postings and no two BD35 compressors would not have the capacity to handle those dual boxes in a tropical climate. The BD 80 is a LBP ONLY compressor so it is less efficient in a duel temperature application. A BD50 for refrigerator box and a BD80 compor for freezer would be the correct application. Again if a boat stays above Latitude 27N daily energy consumes is much less. Still the major problem with 12 volt refrigeration on boats 35 to 50 foot is they normally lack the on board DC current generating power grid capabilities that you have. Don't you also have a generator and a portable Honda. The cost of 12volt refrigeration is only the small investment compared to the costs to support its daily direct current power grid.


A spill over is not a dual temp installation, its a single temp installation.
The fridge is not cooled directly, its passive, you have a freezer with an air leak, not an actual dual temp installation. The compressor controller only knows cold plate temp in my installation, if I had dual compressors, then that would be a dual temp installation as one would sense fridge cold plate temp and then other freezer cold plate temp.

Yes as I said I do have a Honda and run it on average about 1/2 to one hour a day, except when Iím making water. But that isnít to make up for a shortage of power, itís to extend the Solar day in Winter. Summer I wouldnít have to run it, except to make water.
A Honda is $1,000 and will run for years, a small portion of what a DC refrigeration system that will support a larger than 10 cu ft box costs.
So, back to the original question. Itís that you consider a 10+ cu ft fridge / freezer to be to big for an average boat, correct, due to excessive power consumption, correct?
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Old 14-07-2019, 11:20   #14
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Re: 12v refrigeration system for 11 sqft

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A spill over is not a dual temp installation, its a single temp installation.

So, back to the original question. Itís that you consider a 10+ cu ft fridge / freezer to be to big for an average boat, correct, due to excessive power consumption, correct?
Your answers are each boat owner can do the math and determine how much to spend on up grading his Direct Current power grid to support refrigeration for boxes 10 cu ft and larger.
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Old 14-07-2019, 11:48   #15
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12v refrigeration system for 11 sqft

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Your answers are each boat owner can do the math and determine how much to spend on up grading his Direct Current power grid to support refrigeration for boxes 10 cu ft and larger.


Pretty much, yes, but there are other factors in play.
In the Bahamas, good steaks just werenít available, not that I could find anyway, not at any price.
So my ability to freeze and take with me 100 lbs or so of meat both saved me hundreds of dollars as I can buy excellent filletís etc on post at the Commissary, plus it had us eating much, much better meat than you could any other way.
This is why we have an Engle as well as the 14 cu ft spillover, because I hate gristly overpriced low quality meat.
Also the Engle is a back up In case of need. I like back ups.

I know the resorts get good meat some how, I just never cracked that code. I assume they may have it flown in?
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