The team behind BrewPi are at it again! This time they have created an online guide showing how to convert a min-fridge into a Raspberry Pi & Arduino controlled fermentation chamber. In it, they describe 3 possible options:
- Option 1: Make a simple switched power cord, without hacking into the fridge electronics.
- Option 2: Make a switched power cord, but also override or remove the thermostat.
- Option 3: Rip out the thermostat and fully integrate the SSRs into your fridge (which is what [Koen] and [Elco] did).
First things first though. They had to clean the fridge. And depending on where they got it or how long it has been unplugged for, the inside might have been pretty rank and disgusting from mold growing out of every corner. This took a good hour or so to clean properly lest the brewing process get infected with external grossness. This is all worth it because a well-controlled fermentation chamber results in a superior batch of beer.
They put their laser cut case on top of the fridge, holding an LCD, Raspberry Pi, Arduino and the BrewPi Arduino shield. The Arduino reads the temperature sensors inside the fridge, the beer and the ambient temperature. Then it controls the SSRs they added to switch the compressor and a heater. Then, the cables were routed through the fridge and take control of the compressor.
[Elco] and [Koen] added two SSRs: one to switch AC power to the compressor and start relay, the other to power to a heater inside the fridge. But, they did need to gain access to the compressor and make a few changes. For one, the two SSR’s will be added with one of the AC terminals connected to LIVE (brown) and the other to the heater and the compressor.
No matter which method is chosen though, the end product will allow anyone to monitor and easily control the temperature range of your micro-brew, along with being able to log data and produce web-embedded graphs like the one shown below. It works by using the Arduino attached to run the temperature control algorithm autonomously, reporting to the Raspberry Pi for its web interface and data logging.