Cheap temperature/humidity sensor? (re: BLE vs 433/915MHz)

Hardware
1

I’m looking to get a couple of cheap temperature/humidity sensors to monitor my partially finished basement and possibly other parts of the house.

Right now I’m interested in BLE sensors (Xiaomi Mijia “LYWSD03MMC”, Govee, Shelly H&T, etc) and 433/915MHz (Acurite, Ecowitt, Ambient Weather, etc). (I already have RTL-SDR dongles so that isn’t an problem)

I’m fine with any DIY solution but I’m looking for something reasonably cheap. It seems like the Xiaomi Mijia devices from Aliexpress are about $5/ea which is probably my best option? The others are considerably more expensive ($15+) and I’m not sure they are “better” ?

2

I am very happy with my nine LYWSD03MMC sensors, in particular their value for the price. With nothing but a web browser they can be flashed to an open firmware with tons of customization options. BLE range is limited, but a nearby esp32 can easily relay their data over IP. I have most of them in very humid grow cabinets (exotic tropical plants) and in nearly two years have only had one failed display, but it still transmits data accurately (it’s monitoring my refrigerator now).

I also have Zooz XS Z-wave (900mhz) sensor in each bathroom, and they work well. Range and battery life are slightly better than BLE and the option for direct associations is a nice bonus.

3

I bought 4 of the LYWSD03MMC Xaomi type, but i tried to update them to the to be used firmware, but i could not do that. Search for it yourself before buying.
If i am doing something wrong, please let me know, as i want to use them!
Read this page: Xiaomi has released new 2.1.1 firmware · Issue #298 · atc1441/ATC_MiThermometer · GitHub

4

Thanks for the reply. I actually went ahead and ordered them and already received them. They are updating fine to the custom firmware and so far look great!

Here is the seller if anybody is interested: https://www.aliexpress.us/item/3256806777183039.html?spm=a2g0o.order_list.order_list_main.5.33c21802WRBr64&gatewayAdapt=glo2usa

($2.98/ea plus shipping)

5

Does anybody know if there is an accurate way to calibrate the temperature and humidity offsets? So far I’ve only flashed two of the devices but the are both showing different values for both temp AND humidity)