Pimp my fridge!

I have owned a Russell Hobbs RH8WC1 wine cooler for several years. Since I’m not a wine drinker, the fridge serves as a quickly accessible depot for all kinds of drinks next to my desk. But I often use it to store fritz-kola, a German soft drink brand that adds a lot of caffeine to its cola.

That is where the name of the project comes from: fridge-kola

The refrigerator has only a few functions. It is possible to turn on and off an LED in the interior by pressing a button. In addition, it is possible to set the temperature between 8°C and 18°C via two other buttons. Since it is a device without a real coolant circuit, but with peltier elements and two fans, it gets correspondingly loud at low temperatures. The only advantage of this technology is a fairly low power consumption of around 30W.

What can now be improved on such a simple device?

  1. The algorithm to control the cooling unit, depending on the set target temperature, is not very smart. This is manifested by the high speed of the fans, which is not regulated down even when the target temperature is reached. A lot of power can be saved here.

  2. The light in the interior does not turn off by itself. Much nicer would be a knock on the fridge as a light switch and a timer that automatically turns off the light after n seconds. Inspired by the super expensive LG InstaView refrigerators.

  3. I only run the fridge when there are really drinks in it. Therefore, it is important for me to know when the device has reached its target temperature. Who likes to drink warm cola? How about a Home Assistant integration and a push notification to the smartphone?

In the device there are two places where electronic components have been placed. One place is quite conventional on the back. Here is the power supply and the control board for the two fans and the peltier element. However, this “main board” is inherently dumb and can’t do without a sister board. Exactly that is located in the handle of the fridge, a rather unconventional place. All logic takes place here. In the following I will therefore call it: Logic Board.

To transform the refrigerator into an IoT device, I will rebuild this logic board with more powerful components in this project.

Logic Board

RH8WC1 Logic Board Topside
RH8WC1 Logic Board Topside
RH8WC1 Logic Board Backside
RH8WC1 Logic Board Backside


PCB Size: 174mm * 18mm

The B-value of the NTC used is currently unknown. The sensor may later be replaced by a DS18B20 (only 2-wire) parasitic sensor. This can be read out via 1-wire.

No. Function Description
1 NTC Thermistor
2 NTC Thermistor
3 GND Ground
4 VCC +8V
5 PWM / FAN Cooling
6 LED HIGH = off

Creating a new Logic Board

What is replaced by which component?

  • Microcontroller (PIC16Fx?) + Segment Display -> Wemos TTGO ESP8266 with 0.91" OLED
  • We add a SW-420 Vibration Sensor for our “Knock Knock” function
  • Optional: NTC -> DS18B20 1-Wire Temperature Sensor

to be continued!