Best way to monitor fridge/freezer doors with smart sensors

[glock100]

I’m setting up a way to monitor my fridge and freezer so I’ll know if a door gets left open or if the power cuts out. I’d like to know though what others are using.

My current plan is to drop in a budget Zigbee sensor and swap the coin cell for AA batteries to handle the cold better then seal it in a ziplock bag. There’s a Zigbee repeater nearby so I’m hoping the signal won’t be an issue.

Before I go ahead, I’m wondering if I’m overlooking something. Are there better sensors designed for this kind of environment or is this DIY approach good enough? I also considered building an ESPHome setup with wired probes snaked through the seals, but that feels like more work than necessary. Has anyone tried both approaches, and which one gave you the most reliable results?

 

[dr4zy]

DIY Zigbee approach usually works fine, especially with a nearby repeater, just make sure the sensor is sealed well against moisture and extreme cold

 

[Esprs0mart1ni]

@glock100 I like your DIY approach, especially the AA battery swap, but be very cautious about two things. first, the Faraday Cage Effect cause the metal appliance walls will severely weaken any wireless signal (Zigbee, Wi-Fi, or Bluetooth).
also make sure those AA batteries are Lithium (like Energizer Ultimate Lithium). Alkaline batteries have terrible performance in freezing temperatures and will die very fast, negating the benefit of the swap.
If the Zigbee signal fails, the wired probe is the best workaround.

 

[CherryL3mon]

I’m setting up a way to monitor my fridge and freezer so I’ll know if a door gets left open or if the power cuts out. I’d like to know though what others are using.

My current plan is to drop in a budget Zigbee sensor and swap the coin cell for AA batteries to handle the cold better then seal it in a ziplock bag. There’s a Zigbee repeater nearby so I’m hoping the signal won’t be an issue.

Before I go ahead, I’m wondering if I’m overlooking something. Are there better sensors designed for this kind of environment or is this DIY approach good enough? I also considered building an ESPHome setup with wired probes snaked through the seals, but that feels like more work than necessary. Has anyone tried both approaches, and which one gave you the most reliable results?

I like the DIY zigbee sensor plan, but commercial products like the FridgeAlert or Level Sense Freezer Sentry are specifically designed for this environment, offer battery backup, and can provide both temperature and door open alerts. maybe a combination of your DIY door open sensor and a dedicated temperature sensor is a good middle ground