Hi - I have BrewPi running on a Raspberry Pi with the Arduino Uno and it is used to control my Fermentation Chamber which is a freezer. The heat source is a 100W lamp in a paint can. Typically control is +/- 0.5 degrees. Is this a normal profile or can it be tweaked? All the settings are stock and I have been reluctant to change them.
You are only showing the beer temperature, not the fridge temperature and fridge setpoint. My analysis will be very limited:
You have a lot of fluctuation in your beer temperature. I assume you are not using a thermowell and have taped the beer sensor to the carboy. You should fix that first. You are not measuring your beer temperature, you are measuring a combination of fridge air and beer temperature.