Skip to main content

Fridge Monitor

FridgeMonitor.jpg

This BrewskiTech project guides you in building a refrigerator monitoring system using basic electronic components on a breadboard. The system integrates with Home Assistant, allowing you to view and automate fridge and freezer monitoring from any browser or mobile device.

Features:

  • Monitor fridge and freezer compartment temperature/humidity via Home Assistant (browser or mobile)
  • View historical temperature/humidity graphs for both compartments
  • Protect fridge contents with Home Assistant automations and alerts
  • Non-invasive installation—no modifications required to the refrigerator
  • Thin FPC cabling passes through door gaskets to minimize air leaks

All source files are available in the GitHub repo.

Video Tutorial​

A video tutorial is available on the BrewskiTech YouTube channel, which can be found here.

Building the electronics​

The section of the video tutorial on assembling the electronics starts here.

Electronics Plans​

A fritzing file is available for download in the github repo.

Breadboard Plan breadboard

Schematic Diagram schematic

Electronics Materials​

Materials needed:

  • Wemos D1 mini
  • 1x DHT11 temperature/humidity sensor
  • 1x DHT22 temperature/humidity sensor
  • 2x FPC cable, 6 pin, 0.5mm pitch, at least 300mm length
  • 4x FPC PCB Converter Board, 0.5mm pitch to DIP (0.1" spacing)
  • 5V USB power supply (an old cellphone charger will work)
  • Half-size breadboard
  • Breadboard jumper wire kit

Installation​

The section of the video tutorial on mounting and installing the electronics starts here.

Installing sensors on the refrigerator​

We used packing/strap tape to mount the temperature sensor cables to the refrigerator. Make sure to wipe away any condensation on the inside surfaces of the refrigerator compartments before placing the tape to ensure good adhesion.

Home Assistant setup​

The section of the video tutorial on configuring the device in Home Assistant starts here.

YAML configuration​

The latest YAML file can be found here.

esphome:
  name: garage1

esp8266:
  board: d1_mini

# Enable logging
logger:

# Enable Home Assistant API
api:

# Allow provisioning Wi-Fi via serial
improv_serial:

ota:
  - platform: esphome
    password: !secret esphome_ota_password

wifi:
  ssid: !secret wifi_ssid
  password: !secret wifi_password

  # Enable fallback hotspot (captive portal) in case wifi connection fails
  ap:
    ssid: "Garage Fallback Hotspot"
    password: !secret wifi_backup_password

captive_portal:

switch:    
  - platform: gpio
    name: "Onboard LED"
    inverted: true
    pin: D4
      
sensor:
  - platform: dht
    pin: D7
    temperature:
      name: "Temperature"
    humidity:
      name: "Humidity"
    update_interval: 10s
    model: DHT11
  - platform: dht
    pin: D6
    temperature:
      name: "Freezer Temperature"
    humidity:
      name: "Freezer Humidity"
    update_interval: 10s
    model: DHT22
  - platform: dht
    pin: D5
    temperature:
      name: "Fridge Temperature"
    humidity:
      name: "Fridge Humidity"
    update_interval: 10s
    model: DHT22

Automation​

Now that the hardware is setup and working in Home Assistant we can create automations that will make the monitoring system even more useful. The following are two automation ideas.

Freezer Temperature Alert​

If the freezer temperature gets above freezing then that probably means something is wrong, but the temperature could go above freezing for a short time after the door is opened or during a defrost cycle. To guard against false postives we should include a duration so that the temperature has to be above freezing for some amount of time before a notification is sent.

This can be accomplished in Home Assistant with an automation like this:

  • Trigger: When Freezer Temperature is above 32 degrees for 10 minutes
  • And If: none
  • Then Do: Send notification to user's phone with the message: "Garage Freezer is too warm!"

See this part of the video for more detailed instructions on creating this automation.

Fridge Temperature Alert​

We can create a similar automation to send a notification when the fridge temperature is too high, but we might want an additional condition in case the fridge temperature is below freezing for too long (we don't want the food in the fridge compartment to freeze, right?).

This can be accomplished in Home Assistant with an automation like this:

  • Trigger: When Fridge Temperature is above 45 degrees for 15 minutes
  • Trigger: When Fridge Temperature is below 32 degrees for 30 minutes
  • And If: none
  • Then Do: Send notififcation to user's phone with the message: "Garage Fridge temp is wrong!"

See this part of the video for more detailed instructions on creating this automation.