Low cost, battery powered temperature sensors

I’m looking for suggestions for low cost, battery powered temperature sensors. I will be placing these inside a few HVAC ducts to monitor supply and return air temperatures, so I won’t have any ways to run power to them. I looked briefly into the ESP8266 system, but it seems battery life would be an issue since it is wifi based.

I’ve also looked into some of the 433MHz stuff, but don’t have much knowledge of it. It seems with the 433MHz stuff I’d be pretty limited in how many sensors I can utilize as it doesn’t appear that they have unique IDs that they broadcast with.

Any suggestions?

These are currently running $27 each in the U.S. on Amazon:

I have a couple and they work for my home needs.

I have ordered 3 of this:
I stil have not received, but they are reportedly known to work. But you need Zwave at your instalation.

There are a few 433 MHz temperature sensors mentioned in this thread

I like how they have temp integrated into a door sensor. I wonder if these are available in the U.S.

I bought two of these:

And run a MySensors gateway on the same Pi that is running HA. Batterylife is no issue at all.


I’ve been looking at the xiaomi stuff. Its not dirt cheap, but they are probably the cheapest non-DIY option out there. $26 for the gateway and then $9/sensor. Still would add up, though.

I do like your idea of monitoring HVAC ducts. I’m going to have to do that.

I just came across the xiaomi sensors yesterday. I have a HUSBZB1 zwave/zigbee stick. I wonder if I could pair the xiaomi sensors directly to the stick instead of using their hub.

Nope, does currently not work with bellows/zha.

The issue is open since end of august: https://github.com/rcloran/bellows/issues/43

I don’t know much about other brands but I have Xiaomi sensors running on batteries for over a year without any concerns.

If battery life is an issue, maybe enocean could be something for you…
Not tested thoung, just read about today

The problem i have with the xiaomi sensors is the frequency that they update.

You cannot use them fro control as the period between readings is long and unpredictable.