I installed 15 Ruuvitags in a laboratory for room monitoring at the end of October, this was the first stage of the project, we will extend the project even further, our customer uses the data to further optimize his production process. Now I have observed that a Ruuvitag since about November 13th shows a temperature drift of about one degree compared to the other Ruuvis. See also the diagram, the yellow line is the Ruuvi with the temperature drift, the Ruuvi with the red line is about 30 cm away and the rest of the room has a relatively equal temperature curve, except the purple one, which sits on a refrigerator and can be ignored here. Interestingly, the sensor only drifts with temperature and not with air pressure or humidity (see the other diagrams). All Ruuvis have the same firmware, 2.5.9. After a short review of the specifications of Ruuvitag and Bosch BME280, this drift is apparently still fully within the tolerances, although I didn’t find any exact information about the temperature drift over the lifetime of the sensor, only the general statement “Minimum/Maximum values of drift, offset and temperature coefficients are +/-3 delta over livetime” I would just like to know if there is an explanation for this behaviour, especially if the air pressure and humidity stay the same (because I read that the temperature value is used for the correction of the other values when I fly over it), if someone has already observed something similar or if someone knows the datasheet of BME280 better than me .
Many thanks in advance. Many greetings