While collecting data on my current refrigerator to determine if it makes sense for me to replace it, I placed a data collector inside the refrigerator to monitor how the temperature changes throughout the day and also to see when and how long the refrigerator door is open.
The data logger was an Arduino Uno with an Adafruit Data Logging Shield, a DS18B20 temperature sensor and a photo resistor to detect when the door was open/shut.
Below is a 24 hour graph detailing the temperature swings and the frequency at which they occur. I was quite surprised by how often the refrigerator cycles on and off. I assume that the temperature spike at 11pm was due to the freezer going through its defrost cycle.
Also included in the graph (in red) is when the refrigerator door was opened and for how many seconds within that one minute period that the door was open. It’s interesting to see the effect that opening the door has on the temperature.
Has anyone else ever put a temperature logger in their refrigerator? And if so, is my temperature cycle normal?