I also have a bunch of battery powered sensors (of various sorts, about 30 or so). I feel like my life is devoted to replacing batteries.
I see discussions about this periodically but thought I would see if 2025 brought new results. USA based:
Are there good, reasonably pretty Temp/Humidity sensors that are mains powered? Or USB powered in stick form so I could use a small brick with no wires, just a USB port.
Or… is anyone selling a case with AC plug for building espxxx devices that can plug into a wall? Gluing a wart into a box is kind of ugly, someone could make a resin encased power section with safe +5 or +12v inside for projects?
Heck — how about POE devices?
Anything but ugly glued together black project boxes and wall warts.
I may be missing it, but none of those seemed along these lines. Looking for something more like the project in the link in my OP that I could buy (at least the case), or better yet manufactured so it’s smaller and prettier.
Interesting, that photo is quite different from what it looks like stuck on the microwave. The microwave image looked like it was a bunch of pieces required strung together with wires.
That really does look like what I want, I can put in 110v outlets with USB output easily.
The first image (“microwave”) just shows of the magnetic mount and an external probe you can put into (preferable) dead meat for example. The thing is very modular like the text explains and you might even find better solutions for your use-case by browsing more photos
Still useful to read the text as it explains it can be used with or without external probe/battery/etc.
OK, I have one (and that right angle) coming to see how it goes. If that photo you used was on the product page it would help, it was hard to tell scale from the other photos.
Despite wanting small as I think about it am a bit concerned about waste heat’s impact on it (including if I put a USB transformer in the outlet). But I’m assuming that is more or less a constant offset and I can just adjust with a calibration setting in the code. Hopefully. Mixed blessing having a very compact temperature system, it’s prettier, but maybe not as accurate.
So I’m going to stick with ugly (perhaps not big).
The photo works, sort of – but it has to sleep about 95% of the time to have the temperature of the ESP board not make the reported temperature wildly wrong. And you can do that, and it works – but it defeats at least some of the nice aspects of mains powered wifi. Like being able to include it in network monitoring and know if it fails. And accuracy – I’m finding that it sometimes heats up a bit, you get strange spikes. This is inside a closed garage, and I had another DHT also monitoring it that showed no change in that time interval. I can only assume for reasons unclear the board did more work for a bit and warmed up? Who knows – but wrong.
The vendor says it is really intended to be used with a temp probe, not the sensor on the board, as it requires a lot of adjustment to account for generated heat (they said). I suspect this wired one would work quite well. And I would think I could run it without sleeping then. But having the wire dangling from the outlet is… well, a bit ugly.
It would be nice if they had a probe, in white, that would plug in and stick out the bare minimum distance to be accurate without sleeping. Or just to be accurate.
So I’m still on the lookout for a nice, not ugly, mains-powered, wifi Temp/Humidity. Something to plug into half an outlet, or USB in an outlet, and be done - no more battery swaps, etc., but not something any guests immediately say “what’s that thing”?
), and have a quite small white housing. 
