Experience with temperature sensor in a freezer

Does anyone have experience of using temperature sensors in domestic freezers?
The ideal temperature of a freezer should be -18C and I want to monitor our freezers for rising temperature if, for example, the mains fails. (and yes, my HA will continue to run if that happens)

Currently I’m using a standalone range of sensors from Govee but I want to move everything into HA.
Room temperatures are easy, but the two types of Tuya sensor I’ve tried don’t do the job at low temperatures…
The zigbee version just flatlines at -10.
The WIFI version will display the temperatures but is VERY slow to respond. A three hour delay in reporting a temperature rise isn’t much use for an alarm and the UPS on my HA would drop out before reporting a problem.
The Smart Temperature/Hygometer from Risoon quotes ‘Temperature measurement range: -20℃~60℃’
Anyone any experience of that?

The LYWSD03MMC (BLE-ATC firmware) has been working well for me. I am not a fan of CR2032 batteries but they generally last multiple months and since I had great results in terms of reliability, range and low temperature monitoring I didn’t consider other options. I have a single, centrally located BLE gateway running OMG. Monitoring 2 freezers

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I’m using Aqara sensors. They work fine except the battery percentages are meaningless.

I have used Wireless Sensor Tags (no freezer at the moment).

You need a base station (small and not very expensive) but the radio link is easily strong enough to penetrate a freezer cabinet. There is a HA integration, though it is old-style yaml:

The integration is cloud based, which you may not want, but pretty robust. Batteries are CR2032, which means that life at freezer temperatures is only a couple of months - otherwise it’s six months or more, depending on configuration. You also have to wrap them up in ziploc bags to prevent condensation.

+1 here on the Xiaomi BT temperature sensors. Dirt cheap and work great in all sorts of applications. I don’t even remember the last time I changed the battery in the one in my deep freezer. I’ve also found them to be surprisingly accurate and consistent in their readings of both temperature and humidity.

Hi,
I’m using a ds18b20 sensor connected to a wd1m-esp8266 board with tasmota. The sensor is inside the fridge and the board is outside.
Works flawlessly for years now.

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I’ve been very satisfied with YoLink sensors in my fridge and freezer. These devices require a hub and the data is not local, so that could be a showstopper for you. But the LoRa connectivity is incredible and I’ve had rock solid connection through the refrigerator walls and across the house. Seamless integration with HA, with updates every 5 minutes.

my two zigbee devices working for many months now. see below for model numbers.

INKBIRD IBS-TH2. Lithium batteries, nonrechargeable, for the device. Based. Works very well.

I wasn’t happy with the IBS-TH2 (temperature only version), I often didn’t get any readings for hours or even days.

Now using the Switchbot Indoor/Outdoor Thermo-Hygrometer (and a Shelly Plus Plug S as a passive bluetooth proxy to receive the data). The battery is still at 100% after 2 months. Works absolutely fine!


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Poor BT proxy coverage?

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I was using the same Shelly BT proxy with the Inkbird as now with the Switchbot. The Inkbird didn’t even work reliably when positioned close to the Home Assistant Raspberry itself, without any proxy…

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Thanks everyone - there’s lots for me to consider there

Is your bt proxy compiled with framework esp-idf?

I’m just using the Shelly’s out-of-the-box BT proxy functionality in passive mode, which is working fine with all my Switchbot and Xiaomi thermometers. Tried to change it to active mode for the Inkbird, which seemed to improve the Inkbird’s reliability at first, but ultimately didn’t help either.