mains or DC powered fridge/freezer

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mains or DC powered fridge/freezer

Postby franks » Wed Oct 07, 2009 11:42 am

Im researching getting aprox 350-400lt size fridge/freezer trying to find lowest power compsumption, looking under 800wh per day. (5+ star rating)
I prefer mains powered but will a consider DC powered fridge/freezer, Like to spend upto $2000
like to hear ideas and suggestions.
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Re: mains or DC powered fridge/freezer

Postby Gordon-Loomberah » Wed Oct 07, 2009 7:22 pm

You could spend a lot less and add your own insulation to a less expensive fridge! Most fridges these days seem to have very thin walls, and the power consumed by a fridge is basically equal to the heat that is gained by the interior through the insulation, plus the minor amount you lose from opening the door. (I calculated what that was equivalent to once, and from memory it was something like: for a 250l fridge, the loss of cold air and replacement by warm air required the fridge to do extra work equivalent to cooling 60ml of water from room temperature to 4C. ie, its not a lot, air has a very low specific heat, and is easily cooled.)
75mm thick polystyrene slabs on the sides and top of the fridge can significantly reduce the heat transfer through the walls and top of a fridge, however you need to be wary of some fridges that have the coils built into the walls, you dont want to have them on the fridge side of any insulation you add.
My old 250l fridge (only, no freezer) used about 0.5kWh/day when I had polystyrene insulation on the sides and top. I probably could have improved that a bit more by adding some insulation to the door as well. Without the insulation it was almost 0.7kWh/day.

Last edited by Gordon-Loomberah on Fri Oct 09, 2009 2:18 pm, edited 1 time in total. Loomberah weather and astronomy including live solar radiation intensity and UV + Gunagulla aquaponics, organic eggs and cherries
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Re: mains or DC powered fridge/freezer

Postby 470rigby » Fri Oct 09, 2009 1:43 pm

If it is any help, my AC powered 520L Westingouse RJ523 Fridge consumes a measured 1000W/24 hr day on average in Winter (room temp averages around 22 degC) and slightly less in Summer. Cost around $1500 and and IMO makes DC fridges seem an expensive option.
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Re: mains or DC powered fridge/freezer

Postby MadMax » Fri Oct 23, 2009 3:58 pm

You guys may be interested in these:

they're very efficient DC fridge/freezers.

Daily Energy Consumption - Standard Test Conditions* 12VDC
*Standard Test Conditions: No door openings, refrigerator 3oC (38oF), freezer -12oC (+10oF).

77Whrs / 6.5AH @ 21.1oC
168Whrs / 14AH @ 32.2oC
348Whrs / 29AH @ 43.3oC

90Whrs / 7.5AH @ 21.1oC
198Whrs / 17AH @ 32.2oC
393Whrs / 33AH @ 43.3oC

272Whrs / 23AH @ 21.1oC
441Whrs / 37AH @ 32.2oC
766Whrs / 64AH @ 43.3oC

360Whrs / 30AH @ 21.1oC
532Whrs / 44AH @ 32.2oC
817Whrs / 68AH @ 43.3oC
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