Remotely monitor freezer temperatures with Raspberry Pi
Elizabeth from Git Tech’d has shown us how to monitor freezers and fridges remotely with a temperature sensor and Raspberry Pi. A real-time temperature monitor dashboard lets you keep an eye on things, and text message alerts can be set up to let you know when the temperature is rising.
The idea came about after Rick Kuhlman‘s wife lost a load of breast milk she had stored in the freezer. To make sure that months of hard work was never wasted again, Rick came up with this $30 solution.
- Raspberry Pi Zero W
- Adafruit BME280 sensor — an integrated temperature and humidity sensor
- Hammond Miniature ABS Enclosure — used to enclose and mount the sensor inside the freezer
- Flat Flex cable — only the flattest cables can bridge the seal of a freezer without causing an air leak
Easy does it: you just wire the temperature sensor directly to your Raspberry Pi. Rick has even made you a nice wiring diagram, so no excuses:
There’s a little fiddling to make sure your Flat Flex cable attaches properly to the temperature sensor. The project walkthrough provides a really clear, illustrated step-by-step to help you.
Everything looks pretty simple according to the installation walkthrough. A couple of Python libraries accessed via Raspberry Pi OS and you’re there.
You’ll need an access key from Initial State, but Rick explains you can get a free trial. The real-time temperature monitor dashboard is hosted on your Initial State account. If you want to have a poke around one that’s already up and running, have a look at Rick’s dashboard.
You can configure your own alert parameters from within the dashboard. Set your desired temperature and how much leeway you can tolerate.
You’ll get a text alert if the temperature falls too far above or below your personal setting.
We can see this affordable fix helping out science labs that need to keep their expensive reagents cold but don’t have the budget for freezers with built-in monitoring, as well as people who need to keep medication at a certain temperature at home. Or maybe food outlets that don’t want to risk losing loads of pricy perishables stacked up in a chest freezer. Nice work, Rick and Elizabeth!
I did something similar. My oil fired heating furnace is in an unattached building . I have a Pi zero monitoring the water temperature. It sends by wifi the temps every 15 mins to my desktop running MYSQL. I have a web page showing the results. A Php script will send an email when the temperature falls below the operating range. It also sends my phone a text through verizon. I use Grafana to display the graph of the last 24hrs. I also am monitoring and recording outside temperatures in a similar fashion. I had a failure this past winter and knew about it before there was any change of temperature in the home.
Maybe you can make a tutorial with making this project. Will be useful. Thank you.
Roger, I’m interested in what hardware you use for sensing the temperature / wiring diagram.
I’m interested too. Maybe onboard BME280 sensor? I need to measure much lower temperature, BME280 ends at 40˚C on the low side. I need about -200˚C for the next overclocking round. Raspberry Pi 4 ends at approximately -88˚C
Nice work! I also did a similar project, I also built mine on the Pi Zero W but used Dallas one wire sensors (https://www.adafruit.com/product/381) connected through an Adafruit perma proto HAT. These sensors are super handy because they come with a long cord, waterproof package, and Raspberry Pi OS recognizes them immediately as thermal sensors. You just read the temperature in Celsius from a file. I pushed my data points up to AWS CloudWatch, which offers dashboarding, alarms, etc.
Thanks for sharing.
I also use the 1-wire protocol. Really simple, although I do have to reboot the pi every so often. I have sensors using cat 5 cable for the freezer and fridge. I also have 1-wire sensors with magnetic switches for the garage doors and for a water (leak) sensor.
I have also used emoncms for logging and graphing values.
You don’t really need Initial state or any subscription based services, just make a Telegram bot in Python to send you the notification when needed.
I wrote a little app a while back to pull data off of this sensor and the SHT31-D. It just publishes to MQTT and you can do whatever you want. I dumped it into a time series database and used grafana to see it.
This is a terrific post…an interesting backstory, a great explanation of the project, and plenty of specific technical information for anyone who would like to replicate or adapt the project. I’d love to see more posts like this and fewer reprints of fluff articles from the RPF magazines.
Whilst Initial State have some great services, an alternative is Grafana which you can also host on the same Pi – keeping it self contained. I have no info on it here but there are plenty of tutorials out there for it.
Thanks for this fridge monitoring project – I’ll definitely be making this one. Thanks!
Great idea. I once lost a load of mommy juice, too. So frustrating – a huge load. Pump and pump again. Don’t forget the pump and dump after a few cosmos. These Babies get sore. If this guy helps one more mommy, he deserves a giant box of cheese sticks and Coors.
Patricia, sorry to hear of your loss as well. Like you, I listened to the video. Sounds like Rick really does deserve some mozzarella sticks as he lost those, ribs and pork in a previous loss. Practical example of the use of Pi and integrative technology.
I’ve built a small PCB which interfaces to the TMP107 temperature probes from Texas Instruments. Telephone cable runs between them in daisy chain fashion. The cottage installation includes a bat house out back, the beach hut and lake with a total cable run around 200 FT and signal run nearer 300 FT.
Typical log entry from a midnight e-mail:
2020-12-15 20:01, 8.3, -11.7, -10.5, -5.2, -27.8, -27.5, -20.9, -24.2, 0.6,
First temperature is the Pi Zero CPU, last is the lake.
Just a thought. Instead of using an external web site as an intermediary for your data, it’s pretty easy to send an email instead. If you address the email to your cell carrier’s email to text gateway, you can even send a text. If you’re sending plain text this is a simple way to deliver it to your phone. My verizon email gateway is @vzwtext.com. You can find them easily with a google search.