BME 280 humidity reading less than actual

[adityap708]

Hi,

I am working with BME280 sensors for over a year now. I currently have 10 BME280 sensors, all from Adafruit. 

8 sensors are showing humidity -8% and 2 sensors are showing +12% humidity. I am checking them against the UT333 sensor and handheld psychrometer. 

I have tried to recalibrate the sensors, by dry baking them in reflow oven at 120c for 2 hours and rehydrating them for 24 hours at 80%+ humidity. 

After recalibration attempt, 2 sensors that were showing +12% humidity are now showing correct readings. but the remaining 8 sensors which were showing -8% are still showing -8% humidity. 

How can I fix this? 

[Vincent]

The temperature value will affect the result of humidity. 

If the temprature sensor already shows some offset compared to reference sensor,  then the humidity deviaiton is expected here.

The temperature sensor accuracy typical value is around 0.5 degrees according to spec. 

So i will suggest you to check again the environment if they are close environment and achieve the homogeneous of whole environment,  which means in each location of this space you have same temperature and humidity.

BTW,  8% is still within the tolerance range of BME280 relative humidity output.