Putting ice in fridges to extend runtime?

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 . . .

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.

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.

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

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

So if you put bags of ice in the fridge, which takes up space, where do you put your stubbies/cans?

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.

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

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.

"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.

Could this replace the frozen water bottle?

Need to look at the ice pack type product.

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