When I previously modified the Mijia temperature and humidity sensor 2, I accidentally broke its screen. So I figured I’d go all the way and convert it into a device powered by four AA batteries.

Now that it no longer has a display and runs on four AA cells, its standby time should easily reach 2–3 years, making it ideal for placement in automated systems, consumables storage, or other locations where visual monitoring isn’t necessary.

The back cover slides into place from bottom to top; you can attach it to the wall using double-sided adhesive, ensuring rock-solid stability.

This design eliminates the need for a battery compartment and spring-loaded contacts, but it does require double-sided conductive tape. I used a 5 mm‑wide strip—though a wider option would work just as well.

Refer to Figures 3, 4, 5, and 7 for details on the tape and wiring. As for the V+ and V− terminals, you’ll need to determine their polarity based on your specific connection setup; I recommend using relatively thin wires.