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Old 11-03-2011, 06:45   #1
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Average Refrigeration Daily Amp-Hours

Who has a experience based daily amp-hour usage for their refrig system while at anchor/mooring with no one on the boat? This is for when you filled it etc and everything was already cold and you then left the boat for days so no one is getting in/out of it all the time.

I know how much mine draws when running, but I've never left it on and left the boat for the week (don't have a battery monitor either). So not looking for electrical load design responses, just some real life numbers.

Thanks!
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Old 11-03-2011, 07:21   #2
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Re: Average Refrigeration Daily Amp-Hours

Don,

It very much depends on:

(1) the type of refrigeration you have (which compressor, mostly);
(2) the size and quality of insulation of your frig; and
(3) the ambient temperature (more in summer and in the tropics).

My 23-year old Adler Barbour draws about 6 amps when running. Under the conditions you mentioned, and in temps of say 60-80 degrees, it runs about 75% of the time. Therefore the 24-hour draw is 6 x .75 x 24 = 108AH.

Less in winter, more summer or in the tropics.

The newer compressors draw less. I would guess a realistic figure for an average installation on a small cruising boat would be between 40 and 80 AH per day. I don't believe the fantastically low AH claims of some enthusiastic marketers and cruisers.

The way to tell, for sure, is to put a small amp-hour counting device in the frig circuit...something like the Watts Up meter. It's a very handy device, and can be had for about $50 these days: Amazon.com: "Watt's Up" RC Watt Meter & Power Analyzer WU100 Version 2 --- SALE!: Toys & Games

Bill
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Old 11-03-2011, 08:22   #3
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Re: Average Refrigeration Daily Amp-Hours

My 4 cu ft partitioned refrigerator/freezer with a Frigoboat, keel cooled system uses about 60-80 amphours per day when I am aboard. If I leave for several days and put a blanket over the top, it drops to about 40-50.

David
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Old 11-03-2011, 08:28   #4
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Re: Average Refrigeration Daily Amp-Hours

Sea water temperature makes a difference, too. We have a Sea Frost 12V air-cooled, single plate, split freezer / fridge. We keep it just cold enough to make ice cubes.

Summer in Maine (night temps in 50s, day temps mid 70s, water temp in 50s) fridge draws ~ 35 amp-hrs.

Summer on Cape Cod (night temps 65-70, day temps in 80s, water temp mid 70s) the fridge draws ~ 55-60 amp-hrs.

Add another 10 amp-hrs for Winter in the Bahamas. More if we add new food or the kids do a lot of snacking.
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Old 11-03-2011, 08:42   #5
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Re: Average Refrigeration Daily Amp-Hours

I have an Engel 35. Uses maybe 20-30AH a day.
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Old 11-03-2011, 08:45   #6
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Re: Average Refrigeration Daily Amp-Hours

smallest frigoboat "O" evap made.......60-80AH/day in 85 deg water and 90 deg air. This can be reduced by putting a bathmat or something similar over the top of the fridge.
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Old 11-03-2011, 08:52   #7
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Re: Average Refrigeration Daily Amp-Hours

Refrigeration? What is that? We built a Igloo 5 day cooler into the countertop with 2" of foam on all six sides. Then sealed between the foam and cooler with expanding foam. Two blocks of ice last two weeks in moderate temps. I don't know about summer yet.
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Old 11-03-2011, 09:14   #8
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Re: Average Refrigeration Daily Amp-Hours

We went for maximum efficiency,

Under regular use, living aboard, in a hot tropical place like Trinidad... Ours uses about 40 -45 a/h per day... Max.

In normal temperate climates, with regular use... about 35 a/h per day.

In temperate climates with "no openings" and a full box... like you described, something less than 20 a/h per day.

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Old 11-03-2011, 10:22   #9
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Re: Average Refrigeration Daily Amp-Hours

i'm using an Adler Barbour Super Cold Machine connected to VD-150 evaporator plate, acting as a refrigerator into an ice box that I built in 2002 - the box is 7 cubic feet using Dyvinycell H30 closed-cell foam, no drains, with 6" of insulation on sides and bottom, 4" at top. The insulation was sealed with an exterior and interior layer of West epoxy and fiberglass. I did not install the water-cooling pump for the compressor (yet). It's likely that some day I shall.

The compressor runs 6 minutes each hour and shuts down, when running the draw is around 6 amps as 12.6 volts.

My power consumption is 14.5 amps / 24 hours, this has been true in Hawaii as well as in San Francisco.

A 120 watt Kyocera solar panel more than pays for the power consumed by the compressor - upshot is zero charging is needed when away from the boat at anchor.

As per prior posts, my experience will have little relation to your experience, as power draw conditions are completely dependent upon ambient temperature inside the boat, sea water temperature (if you're using sea water to cool the compressor and refrigerant), how cold you want the interior of the box to be (e.g., delta temperature between outside and inside temperature), the surface area of the insulation, the R-value of the insulation, the thickness of the insulation, and the compressor and refrigerant you are using.

- rob/beetle
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Old 11-03-2011, 11:18   #10
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Re: Average Refrigeration Daily Amp-Hours

Bill,

thanks for the "watts up" info/link.

MARK (or anyone else),

Sweet job you did with re-insulating your box. if i want to put in some insulation, on a tempoary basis, to see if it does any good what type/kind of material do i want to use?
currently guessing we are using about 110 amps/day to run refrigeration and freezer in the BVI.

thanks
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Old 11-03-2011, 12:32   #11
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Re: Average Refrigeration Daily Amp-Hours

Quote:
Originally Posted by gbanker View Post
Sweet job you did with re-insulating your box. if i want to put in some insulation, on a tempoary basis, to see if it does any good what type/kind of material do i want to use?
Easiest thing to use (if available) is adding something like 1" thick blue-board foam to the inside of the box, sealing with tape as much as possible any gaps.

You also should be measuring temperature over time inside and outside the box, this will give you information you can use to do comparative analysis of temperature rise over time before and after any change.

- rob/beetle
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Old 11-03-2011, 20:59   #12
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Re: Average Refrigeration Daily Amp-Hours

Technautics - 20ah/day, 6 cubic ft reefer with moderate temps.
Tom
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