Putting ice in fridges to extend runtime?

I have been thinking for a while if it would be a good idea to put a bag of ice or frozen water bottles in the fridge to extend the battery life. Has anyone tried this?

My thinking is that if the compressor does not have to come on so often it should extend the battery time. I know ice stays frozen for a long time in cooler boxes but I don't know if it will be the same in this case.
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Reply By: Maîneÿ . . .- Wednesday, Feb 24, 2010 at 18:37

Wednesday, Feb 24, 2010 at 18:37
When your out bush where will you get the "ice" from as you won't even have spare water out there, unless you are in a wet and cold area anyway.

I leave a container of drinking water in the fridge 24/7 and refill it at every opportunity, as yes it does assist to maintain the 'coolness' to the fridge cabinet because water stays colder longer than air.

Maîneÿ . . .
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Reply By: Member - ross m (WA) - Wednesday, Feb 24, 2010 at 18:43

Wednesday, Feb 24, 2010 at 18:43
It works. I usually put frozen bottles of water in there which can be drank as they thaw.
Bags of ice cost money,will melt quicker and cannot be used once they have melted.
The frozen bottles of water are more regualr in shape as well.The 2 litre fruit juice bottles are the best shape

Putting all your food in cold is just as good really. Even things like inflated wine cask bladders or lumps of polystyrene which stop warm air replacing cold air when the lid is opened will help.
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Follow Up By: Member - Russnic [NZ] - Thursday, Feb 25, 2010 at 13:32

Thursday, Feb 25, 2010 at 13:32
I go along with that ross m
Colder the articles the less energy required to keep frozen
Ice can get messy, bottles of water keep thier shape, providing room is left for expansion on freezing.
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Reply By: Member - Mfewster(SA) - Wednesday, Feb 24, 2010 at 18:48

Wednesday, Feb 24, 2010 at 18:48
My Waeco booklet advises against putting ice into the box. Not sure why, but I am guessing they think it might penetrate the sides and quite thin pipelines. If doing it, I think freezing a plastic bottle of waterwould be better than just dropping ice in.
AnswerID: 405789

Follow Up By: Member - Trackker (QLD) - Wednesday, Feb 24, 2010 at 20:33

Wednesday, Feb 24, 2010 at 20:33
A waeco rep once mentioned on a 4wd show that it is not a good idea to add frozen water bottles etc to your fridge. I can remember him saying that if you happen to put it near the thermistor , the fridge will sense that temp as being way too cold and wont actually cycle enough to keep the rest of the fridge cool enough especially up top. It wont hurt anything. I myself wouldn't be too worried about adding frozen bottles. Uptop would be best. cheers, Dave
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Follow Up By: obee1212 - Thursday, Feb 25, 2010 at 08:57

Thursday, Feb 25, 2010 at 08:57
i think the waco rep needs a new career

owen
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Follow Up By: Maîneÿ . . .- Thursday, Feb 25, 2010 at 09:12

Thursday, Feb 25, 2010 at 09:12
Trackker
I understand what your saying, "if you happen to put it near the thermistor" the temp censer will 'see' the temp of the frozen water bottle against it, not the air in the cabinet, it will not turn on the compressor, hence the rest of the fridge cabinet starts to overheat.

Maîneÿ . . .
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Follow Up By: Member - Trackker (QLD) - Thursday, Feb 25, 2010 at 09:38

Thursday, Feb 25, 2010 at 09:38
Yes Mainey. he even mentioned which part of the fridge wall that the thermistor was mounted to but I cant remember. I am not a fridgy but it sounds correct and makes sense if you put a frozen bottle of water against the wall near the thermistor it will measure the temp as below freezing. If your fridge is set on +5 it will not turn on but it would depend on whats in there and how much. So when your frozen bottle thaws enough to turn your compressor on I would guess the stuff up top would be quite warm. Cheers, Dave
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Reply By: Mandrake's Solar Power- Wednesday, Feb 24, 2010 at 19:31

Wednesday, Feb 24, 2010 at 19:31
I've recently been testing a sheet of 10mm thick bubblewrap cut to fit the top of the fridge . It seems to work very well and reduces the number of cycles the fridge does ...It also stops you from losing all the cold air when you flip the lid.!!

Cheers

Steve
AnswerID: 405793

Reply By: Andrew & Jen - Wednesday, Feb 24, 2010 at 20:26

Wednesday, Feb 24, 2010 at 20:26
Hullo Paul
Hmm ... it being after dinner time on a Wednesday, this topic got me thinking.
A few facts and thoughts. 1) air has a specific heat of approx 1/4200 [volumetric] of water. That is, it requires a LOT less energy to cool than water. So even if warm air gets into your fridge, it is cooled very quickly and with little expenditure of energy (battery). 2) Cool air, being denser than warm air, will stay put in a top loading fridge and not be displaced by warm air [unless you really stiir it around] 3) while frozen food and water, etc, will initially reduce the load on the battery, after it reaches equilibrium temp with whatever the fridge has been set to, it will require the same [or similar] energy to maintain it at the set temp as any other food that might be in there, regardless of its frozen origins. I suspect that the best way to reduce energy use is more insulation and reducing the ambient temp - eg, if you have your airconditioner on, maybe put your fridge in the back of the wagon and keep it in the shade.
Hope that helps
Andrew
AnswerID: 405799

Follow Up By: Bob of KAOS - Thursday, Feb 25, 2010 at 08:02

Thursday, Feb 25, 2010 at 08:02
Andrew

Good answer. I like debunking myths by the use of facts and science. I guess the final answer would be to do an experiment to confirm your hypotheses.

I suppose the benefit of the ice in the fridge might be to keep it cold for longer when power is not available (and the fridge wasn't already full of food/tinnies). This might mean that you could have the fridge powered up all day while driving (when there is no shortage of power), then slowly warm up over night as the ice warms up (something that would happen a lot quicker if the spare space in the fridge was just air).

If you were camped for a week and reliant on limited solar power, then the decision would be between storing extra energy as electricity in the battery (and letting that run down over night), or as thermal energy as ice in the fridge (and letting that melt overnight).

Bob
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Follow Up By: Rob! - Thursday, Feb 25, 2010 at 13:33

Thursday, Feb 25, 2010 at 13:33
But with ice in it, the fridge is likely to turn itself off until the ice has melted and the fridge temp raises to the point where the fridge turns on again. This is likely to happen whether you have power or not.
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Reply By: Member - Rod N (QLD) - Wednesday, Feb 24, 2010 at 21:20

Wednesday, Feb 24, 2010 at 21:20
So if you put bags of ice in the fridge, which takes up space, where do you put your stubbies/cans?
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Follow Up By: Bob of KAOS - Thursday, Feb 25, 2010 at 08:03

Thursday, Feb 25, 2010 at 08:03
Rod

You'd have to bite the bullet and consume them.

Bob
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Reply By: Busy Bee - Thursday, Feb 25, 2010 at 00:15

Thursday, Feb 25, 2010 at 00:15
I would have thought one of the reasons for a fridge was to get away from ice which is quite bulky.
If you run an esky it has to be quite large to accommodate the ice. Running a fridge means less space taken up in your rig and all that space is dedicated to food and drink.
The only time I made a mistake was when I thought I was wrong, but I was mistaken.

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Follow Up By: Shaker - Thursday, Feb 25, 2010 at 19:33

Thursday, Feb 25, 2010 at 19:33
Strange, because that is exactly what was going through my mind.
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Reply By: obee1212 - Thursday, Feb 25, 2010 at 09:09

Thursday, Feb 25, 2010 at 09:09
anything you put in the fridge, especially stuff than can hold a lot of heat like water, an be seen as a battery that stores cold. A fridge that can run full on like when you are driving or running a bank of solar, can cool all the stuff for when you are running on the electric battery. The more stuff in there the more stored cold that will take longer to absorb heat. Heat that can be pumped out when you are driving or on 240v or solar.

This the principle that boaties use when they install an eutectic system. (I may have the name wrong). They run the cooling pipes through a tank of non freezing liquid (alcohol probably) so when the engine is running the tank loses a lot of BTU's and can absorb heat from the target food and drink when the engine is shut down. A cold battery if you like.

Its all about transfer of energy whether electric or heat it got the same principle in effect call it what you like.

Owen

AnswerID: 405874

Reply By: olcoolone - Thursday, Feb 25, 2010 at 09:37

Thursday, Feb 25, 2010 at 09:37
Car fridges have an evaporator rapped around the inside to help give constant temps over a large area.

The temp is controlled by a thermostat that regulated the temp inside the fridge, if the fridge is working right, the evaporator should give a near constant temp across the whole evaporator coil.

But the thermostat only senses of a very small area of the evaporator, maybe 25 to 50mm square area.

By adding ice to a fridge may make the thermostat think the evaporator is cold enough and shut the compressor off not giving an even temp across the whole evaporator.

The only advantage of putting something pre chilled into a fridge is it will take less energy to remove the heat until the temp of the stuff you have put into the fridge and the fridge comes to a set point......this is mostly when you are driving.

If you put frozen water in containers, the fridge will draw less energy at start up and more energy after as it has to pull the heat out of the water (water takes more energy to pull heat out off) making you fridge work harder for something that is not needed in the first place.

The only real advantage would be if you were transporting the fridge when it could not have power connected for a period of time and you wanted to help maintain temp.

It's all to do with heat transfer.
AnswerID: 405883

Follow Up By: Maîneÿ . . .- Thursday, Feb 25, 2010 at 10:26

Thursday, Feb 25, 2010 at 10:26
"If you put frozen water in containers, the fridge will draw less energy at start up"

Can you please explain how "fridge will draw less energy at start up" ??

Maîneÿ . . .
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Follow Up By: Bob of KAOS - Thursday, Feb 25, 2010 at 12:50

Thursday, Feb 25, 2010 at 12:50
When you first turn a fridge on the whole thing and the air within it is at room temperature. So the fridge has to work to bring the contained air and the evaporator/internal box/insulation down to the desired temperature. If you put a chunk of ice in there, the ice will help to cool down the aforesaid items, rather than all the work being done by the fridge. The work has been done by someone else's fridge - in making the ice.

Therefore your "fridge will draw less energy at start up".

Bob
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Follow Up By: Maîneÿ . . .- Thursday, Feb 25, 2010 at 16:39

Thursday, Feb 25, 2010 at 16:39
Bob,
your suggesting the word "energy" as in the line "the fridge will draw less energy at start up" is not relevant to electrical energy ? ?

So then can I ask what type of *energy* is it in reference to *at start-up* that obviously changes as the fridge has *started* and then continues to run ??

Maîneÿ . . .
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Reply By: Member - Mike DID - Thursday, Feb 25, 2010 at 09:57

Thursday, Feb 25, 2010 at 09:57
"My thinking is that if the compressor does not have to come on so often it should extend the battery time."

The improvement will be trivial.
AnswerID: 405889

Reply By: Member - Prickle (SA) - Thursday, Feb 25, 2010 at 22:15

Thursday, Feb 25, 2010 at 22:15
Could this replace the frozen water bottle?

Need to look at the ice pack type product.

www.techniice.com

Russ


Life-often hell but never boring.

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