In my experience, most of these ‘off the shelf’ temperature/humidity devices seem to use one of a small set of common low cost sensors. Of the 10 or so different BLE and Zigbee devices I have tried and can still be purchased, the one that seems to yield the ‘best’ results is the Goove H5074
https://www.amazon.com/Govee-Thermometer-Hygrometer-Bluetooth-Temperature/dp/B07R586J37
It lists a humidity accuracy of ‘humidity is ±3%RH.’ However, most of the devices out there seem to say about the same. When I say this is the ‘best’ I have experimented with, that is a subjective statement, as I have never measured them against a professional calibrated device.
Not sure if it is helpful, however below are two humidity charts from a couple of my sensors. Different time scales and sensors, so it is not trying to show any comparison. The first chart shows two Goovee H5052 sensors in refrigerator and freezer. These devices are no longer sold, but I believe they may have a similar sensor to the H5074. Unfortunately, my H5074 is used to monitor stove temperatures and as such does not experience as dramatic humidity variations as the H5052’s shown. The second chart shows a shorter time scale of a person taking a shower in a bathroom. The sensors in this bathroom are Xiaomi LYWSD03MMC and Goove H5072, of the devices I have these seem to be the poorest of the humidity sensors, with the Xiaomi better and the H5072 the poorest.
Be careful of ‘close’ model numbers in the ads and pictures that show one unit, but list a different units model number.
I’m not sure what, if anything, you can take away from the charts. The H5052 sensors seem to react quickly and track well, however my example case is in very low temps of refrigerator/freezer. Not sure if high temps will cause different response.
The ‘recovery’ time for these sensors when they get in a high humidity range seem to be one of the issues, it seems that they take a while to ‘dry out’, I am guessing the unit in the freezer is fairly responsive because the water vapor in the freezer is ‘less liquid’ that these cold temps.
I have better over all experience with BLE units as opposed to Zigbee units. The ‘best’ zigbee unit I have experimented with is the Sonoff TH01, it seems to track with a Govee H5052 very closely. However, I never did put the Sonoff TH01 in a area with as wide a range of exposure as the other units.
Good hunting!
and useful area for both professional and home automation work. I live part time in a town with a university that is doing some interesting IoT farm work and also the area is one of the largest professional marijuana growing areas, both have offered some interesting talks on their work.
