Fridge Loaded "Fully or Partly" Myth Debate

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The current stable ambients were a good opportunity for me to conduct further testing on the contention of keeping a fridge packed full in order to minimise energy input.

Using appropriate instrumentation, I firstly tested the fridge empty, then loaded it fully with plastic jars full of water at a temperature setting of 4 degrees. The Ah consumption was essentially identical in each case.
The compressor duty cycle changed but the total Ah remained the same.
I then removed the upper layer of contents and repeated the test, again with the same result as before.
Then I placed several layers of bubble-wrap above the contents to fill the void and found that the Ah consumption was reduced by nearly 10% ----Eureka!!

I got to thinking hard about this. The only reason to put electrical energy into a stabilised fridge is to remove the heat ingress getting through the fridge insulation. Heat enters through the cabinet sides, bottom and top and first encounters the evaporator plates where it is absorbed before it can reach the contents. But look at those evaporator plates, they are not on the bottom or top, and at the sides they do not even reach all the way to the top. Heat is pouring in through the lid and the upper shoulders of the cabinet directly onto the contents. When I placed bubble-wrap on top of the contents I had placed further insulation in its path.
So I repositioned the bubble-wrap outside the cabinet, on top of the lid, leaving a void below the lid above the contents, and repeated the test. The result was that the Ah energy was reduced to nearly as much as when it was inside the cabinet.

So the MYTH IS BUSTED on simply keeping the fridge full to save power.
But the MYTH IS PROVEN on adding insulation between the top of the contents and the heat source.

On trips, I usually add a folded towel above depleted contents to stop bouncing but have taken no note of fridge Ah change, but it seems to have that advantage. Putting a folded towel over the lid if no room inside with it hanging down over the cabinet shoulders could be a good idea if the fridge is chockers too. In fact even a mat of that 10mm HD foam on the inside bottom could be beneficial too. Few fridges have really adequate insulation after all.

Watch for me on the ABC Science Show. lol