any 2025 option without c-wire or plug?

[PeppyBlueBear]

So I've been digging around for a smart thermostat that's actually battery powered... no C-wire, no plug-in adapter. Haven't had much luck. Everything I find either needs a C-wire, comes with one of those power extender kits, or expects you to stick a cable in the wall.

I don't mind swapping batteries, but it seems like these things must chew through power with the Wi-Fi, screens, and sensors. Maybe that's why no one's building a true battery-only option? Has anyone in 2025 found a thermostat that runs clean on batteries for more than a couple months? Or is it basically a choice between rewiring for a C-wire or living with one of those kludgy "wireless but not really" solutions?

 

[sw8revenge<3]

This is a very common issue for people in older homes and it’s a big reason why a lot of smart thermostat companies include power extender kits. Some of the newer Google Nest models and Emerson Sensi thermostats do not require a C-wire, and they use the power from your heating and cooling system to charge a small internal battery, but they still need to connect to the other wires. There are a few options, like the Sensi Lite, that are designed to run on batteries for a while, but you might find that the battery life is not as long as a regular thermostat because of the added features. The most reliable solution is almost always to have a C-wire installed, even if it's a bit of work.

 

[MommaPhoebs58]

I've been looking into this too and since we just switched to the Nest Hub, I'd also recommend the Google Nest Thermostat. It works without a C-wire, though I've read many people still use the optional power connector for more reliable performance. I agree with @sw8revenge<3 about the Emerson Sensi. I've read the ST55 is a solid choice, but again we prefer everything streamlined with our Nest Hub.