I have made some tests with 4 ruuvi devices, two analogues hair hygrometers and two testo hygrometers and I noticed that accuracy in lower region (33 % r.H and lower) is significantly below 3% r.H I would say about 3-6 %. I have made a simple two - point calibration using MgCl2 (33% r.H) or alternatively LiCl (11,1%) as second point and found that accuracy in lower region significantly improves. (I know that 11% is outside specification but nevertheless it is doing fine with 2-point calibration). Would it be a great effort to implement two point calibration in any of the next releases? 2nd calibration point could be 11,1% as it is used for example with testo hygrometers or even better it could be configurable.
I’m sure this has already been discussed here at some place or internally in ruuvi team but I couldn’t find it. Of course you could say this can be done easily outside the device, however it would be a great thing to have implemented inside the app. But maybe only few users are interested in this feature.
Thanks a lot for your feedback of ruuvi team and from other users if this feature would be interesting.