For a laboratory setup, I am using BME280 - SparkFun Atmospheric Sensor Breakout (with Headers). I have ordered 5 items and none of them reads the humidity correctly (which is verified by measuring with independent two other sensors near the BME280). I use it in a temperature controlled room where the humidity should be 40% which is what the other sensors show. BME280s show at least 80% humidity and 3 of them even show always 100% (I think the reading is overflowing). I wonder if the soldering done in from the Sparkfun team had created an issue with the sensor?
There’s no soldering that I did. I basically connected a single item using the I2c lines via simple jumper cables to an arduino. The temperature and the pressure works well. By different sensor I meant that I just disconnected one and tried the others so with the same configuration to see if maybe one sensor is good. However all had very high humidity readings yet not identical.
Datasheet has something about what you’re experiencing.
Reconditioning Procedure
After exposing the device to operating conditions, which exceed the limits specified in
section 1.2, e.g. after reflow, the humidity sensor may possess an additional offset. Therefore
the following reconditioning procedure is mandatory to restore the calibration state:
Dry-Baking: 120 °C at <5% rH for 2 h
Re-Hydration: 70 °C at 75% rH for 6 h
or alternatively
Dry-Baking: 120 °C at <5% rH for 2 h
Re-Hydration: 25 °C at 75% rH for 24 h
or alternatively after solder reflow only
Do not perform Dry-Baking
Ambient Re-Hydration: ~25 °C at >40% rH for >5d
Reflow happened when the board was assembled, give reconditioning a try and see if things improve.
Unfortunately I don’t have anything besides a regular oven which I can do the baking part but not the rehydration part. I would’ve expected sparkfun to do this already if the soldering is the cause.
Are there any tips on how you can do the rehydration part without a professional climate equipment?