Sensor to use as a freezer alarm?

I’m setting up Smartthings at a club I’m a member of and we have four freezers. I would like to integrate them so that they alarm if they reach a high temperature of e.g. 10 degrees F. The club isn’t occupied all the time so it would need to be an ST-based system in order that we get alerts on our smartphones.

Does anyone know if there is a straightforward solution to this? I’m assuming the temperature probe will need to be in the freezer with a wire to the transmitter outside in order for the battery to be at room temperature. However all that matters is that the solution works and battery life is acceptable.

This isn’t an ideal solution, but I’ve taken the SmartThings branded contact sensors (which report temperature) and removed the existing battery (CR2450’s that do awful in freezing temperatures), them soldered on a 2xAA battery pack. It’s a clunky solution but it’s been working decently well. Battery life has been in excess of 6 months using Amazon Basics AA’s.

Temps in the kitchen freezer are usually right at 0f, and the deep freezer bounces between -10 and 0f.

Editing to clarify that once I soldered on the battery pack, I threw the whole thing on a shelf inside the freezer.

Samsung says SmartThings isn’t suitable for commercial use as it isn’t reliable enough. They specifically mention food spoilage.

Data accuracy and consistency from SmartThings sensors, including those provided by SmartThings directly, resold by SmartThings, or supported by SmartThings, is not guaranteed. Therefore, you should not rely on that data for any use that impacts health, safety, security, property or financial interests. For example, because temperature readings may vary significantly from reading to reading on an individual device, between devices, or over time, those readings should not be used to control heating and cooling in environments where food spoilage, health risks, or damage to physical goods could occur.

Also, the most common reason for freezers to fail is a power outage, and at that point it’s very hard to get a notification from SmartThings because it is cloud dependent for all notifications.

So you might just want to consider a commercial freezer alert instead. But of course it depends on the value of the items that might be spoiled (either financial or reputational).

If you decide you do want to go ahead with SmartThings, there are lots of discussion threads in the forum from people who have done freezer monitoring with various different devices. You can just search on “freezer” Using the magnifying glass icon in the upper right of this page and you’ll find several of these. :sunglasses:

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I use ST contact sensor for my freezer in the garage as well. I set alert to monitor both temperature and freezer door being left open.

I simply use the button battery. Inside the freezer the sensor’d report 0% battery fairly quickly but it continues to work for over a year. To make sure I know it’s time to change the battery I also setup a monitor to alert me when the sensor hasn’t been reporting for 24 hours or more.


Do you have to put the sensor in a plastic bag or something?

I never put my sensor in a bag, I use it as the freezer door open/close sensor as well, so putting it in a bag isn’t practical. I haven’t had issue with it after years of use.

Thanks, I will try that. I have a Sensitive Strip only a year old, but it shows 15 % battery. I am not sure if it isn’t SmartThings battery reporting as being off. Yesterday one of my motion sensors said low battery, when I checked it they were as good as new and I installed them 5 days ago.