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Old 11-05-2014, 09:44 AM   #15
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For those who are promoting leaving your fridge on all the time, I'm assuming your plugged into power. So if that is the case, are you running a chance of boiling your batteries dry well trying to make your fridge last longer..... just asking?

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Old 11-05-2014, 06:45 PM   #16
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Reefer--leave it on?

If you have a modern multi stage converter and it is working properly. The batteries will be fine. You can disconnect the battery(s) and have DC power from a modern converter as well.
The battery(s) are only necessary when you are towing or camping off the grid.
As for the refer. The electric heating element is nothing more than a big light bulb that shows no light. It has a finite life. While they can fail at any time.
If you choose to keep the refer on 24/7/365. I would recommend carrying a spare element.


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Old 11-05-2014, 08:42 PM   #17
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An RV refrigerator operated on 120 volt power will probably average in the range of 250 to 300 watts an hour. They are massively inefficient devices. For reference, my new energy star rated 23 cu ft Kenmore side by side takes an average of 55 watts an hour, about 1/5 of the use of an RV refrigerator.

300watts X 24 hours a day X 30 days a month = 216,000 watt hours a month or 216 kWh a month. If you are paying 12 cents a kWh that is about $26 a month. If you like to toss money away running your RV refrigerator full time is a very good way to do it.

Protagonist: Your statement that "Refrigerators are always more efficient at cooling if they're full than if they're empty" has no basis in fact. A refrigerator simply removes heat leaking into it from the outside, which is determined by the outside surface area of the box and it's insulation properties. It has nothing to do with how full the refrigerator is at all.
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Old 11-05-2014, 10:02 PM   #18
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Quote:
Originally Posted by idroba View Post
Protagonist: Your statement that "Refrigerators are always more efficient at cooling if they're full than if they're empty" has no basis in fact. A refrigerator simply removes heat leaking into it from the outside, which is determined by the outside surface area of the box and it's insulation properties. It has nothing to do with how full the refrigerator is at all.
I beg to differ. Here's the crucial factor you're overlooking: Every time you open the door to the refrigerator, you let out cold air and let in warm air--and when you shut the door, all that warm air you let in has to be cooled down. The more air space in the fridge, the more cold air that can be swapped with warm air from the room. More warm air = more cooling required = higher fridge juice consumption.
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Old 11-05-2014, 10:04 PM   #19
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Reefer--leave it on?

I agree with idroba. Most people pack the refer full of cold stuff. Which shortens the cool down time. Simply because there is less air to cool, plus the assistance of the cold stuff.

In regards to the $26.00 a month. I doubt the heating element is on 24/7. Unless you routinely open the door.

This is where the dorm or apartment refers beat the RV refers hands down if you have shore power. You can purchase 6 dorm refers for the price of one RV refer of comparable size.
When you consider these units run on 55 watts, give or take. With 150 watts of solar and adequate battery and inverter capacity they make a viable alternative.


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Old 11-05-2014, 11:12 PM   #20
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Originally Posted by Protagonist View Post
I beg to differ. Here's the crucial factor you're overlooking: Every time you open the door to the refrigerator, you let out cold air and let in warm air--and when you shut the door, all that warm air you let in has to be cooled down. The more air space in the fridge, the more cold air that can be swapped with warm air from the room. More warm air = more cooling required = higher fridge juice consumption.
Your original statement in full was:

"Refrigerators are always more efficient at cooling if they're full than if they're empty. Put some blue ice packs in the freezer section, and fill the refrigerator section with bottled water, leaving just enough air space for cold air to circulate. This provides thermal mass, and ensures that the refrigerator will not cycle as often as it would if you were just cooling the empty volume."

What is in the refrigerator has nothing to do with the efficiency of the cooling system. Your statement indicated that somehow efficiency of a refrigeration system is dependent on what it is cooling, and that is simply not so. Then in the next post there is talk about the number of times a door is open or closed, which again does not change the efficiency of the refrigeration system. The number of times the refrigerator cycles also has nothing to do with it's efficiency. The "on" time will determine the cost of operation, but will not change the efficiency of the system.

"Efficiency at cooling" (words from the original post) is dependent on the specific refrigeration cycle and the size of the box and would be measured by how many watts of electrical power is necessary to remove the heat leaking into the box itself. If the box is filled with air, concrete blocks, or cumquats is irrelevant.

I believe that the use of the word "efficiency" is where the problem is. The efficiency of the cooling system itself is characteristic of the cooling system only. The cost of operation will depend a little on the number of times the door is opened and how much beer is cooled, but the efficiency of the refrigeration system is an independent item. It may run longer with more beer in and out, but it will not run any more (or less) efficiently.

I am not trying to be snarky here, only factual on how the RV refrigeration system is much less efficient than a compressor refrigeration system used in your home unit. It takes far more power (watts) and over time far more energy (watt hours) than a compressor unit to remove equal amounts of heat from your beer. But weather the refrigerator is full or empty does not change the inherent efficiency of the RV absorption system or the efficiency of the home compressor system one bit.

End of engineer talk... LOL
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Old 11-06-2014, 05:18 AM   #21
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But weather the refrigerator is full or empty does not change the inherent efficiency of the RV absorption system or the efficiency of the home compressor system one bit.
I yield the point.
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Old 11-06-2014, 06:10 AM   #22
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Maybe there is a confusion about how efficient the use of the refrigerator is in relationship to how it functions as a mechanical device. One can improve the overall energy efficiency by not opening the door as often, but as pointed out the mechanical efficiency is a fixed characteristic……. unless we add in the confounding factor of ambient temperature. One can state in general the energy usage for a refrigerator in Alaska may be less than for one in Florida, but again, the basic design will determine the efficiency relative to other refrigeration units.

Did I confuse this enough?
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Old 11-06-2014, 06:26 AM   #23
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Maybe there is a confusion about how efficient the use of the refrigerator is in relationship to how it functions as a mechanical device.
Call it efficiency (a measure of design) vs. effectivness (a measure of usage) and we'll be fine. You can't change a refrigerator's efficiency without changing the design, but you can change its effectiveness. Earlier in this thread I referred to "efficiency" when I should have said "effectiveness," leading to Idroba's correction as to the meaning of "efficiency."
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Old 11-06-2014, 07:57 AM   #24
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I love it when the engineers chime in. I am not an engineer, but probably should have been. I have an architecture education, but an energy efficiency career, prior to getting into the custom cabinet business.

Trying to explain efficiency vs cost to operate is difficult. Like is a gas furnace more efficient than an electric one? The answer people want is what is less expensive to operate. And, the answer to the question about cost to operate is 'it depends'. Not a very helpful answer but one I had to deal with day in and day out.


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Old 11-06-2014, 10:46 AM   #25
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And we can all be friends in the end and enjoy our cold beverage of choice from our refrigerator. I like mine to be very cold, as close to 32 as possible please.
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Old 11-06-2014, 03:04 PM   #26
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We shut ours down between weekend trips ...
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Old 11-06-2014, 05:43 PM   #27
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Ditto
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Old 11-12-2014, 06:53 PM   #28
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I always turned mine off and left the door open when not in use.
My biggest problem was wasp nests, not wear.
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