I used the Sonoff app (Ewelink) that stores 1 datapoint per hour. I configured the Ewelink app to turn on the compressor at -16 Celsius and turn off at -23 Celsius. The freezer was empty.

And it shows temperature cycles every 4 hours, with an empty freezer. Then I turned on super freeze and in about 7 hours it dropped to -38! 

After 24 hours super freeze automatically turned off and temperature returned to -16 to -23 range. I want to repeat these measurements while the freezer is significantly filled. 

So I added 26.5kgs of bricks.

Then the temperature cycles every 7-8 hours. Now I turned on the compressor permanently and want to see how low and how fast the temperature drop.

In about 10 hours it drops to -32 and but then it takes another 14 hours to drop only 5 degrees more to -37 Celsius. So I think the freezer becomes very inefficient below -32 Celsius. Then I turned off the compressor and it takes 10 hours to go from -32 to -16 Celsius. Now my freezer is 28% full (26.5kgs bricks) so I expect that a 50% full freezer can keep the temperature safe <16 degrees Celsius for 17 hours. That sound more than enough

I also want to redo these measurement in combination with power consumption. I want to know how inefficient my freezer is in super freeze mode.