BME280 giving weird humidity measurements

[moiz_elec]

Hello,

We are currently in Beta test with one of our customers before deployment.

We encounter noise spikes around 60% in the humidity data only when the electronics is outdoor. The main electronics is resined and IP and the BME280 is in a PTFE filter.

I am sending 2 screenshots:

• First one is for a module that has been sitting outside for 1 month. Temperature and pressure are OK. You can see random spikes in the humidity data.
• Second slide is for another module, identical to the previous one. It has been indoor for around 2 weeks with clean humidity data and as soon as it went outside some noise spikes in the humidity appeared.

I can also add that when the first module was sitting indoor, it had no errors in humidity data.

In conclusion noise spikes are only present outdoors.

Is that a known issue ?

Do you recommend any action ?

Thanks

[BSTRobin]

Hi moiz_elec,

From your screenshot, the indoor data temperature changes slowly, the outdoor data temperature changes sharply, and the humidity changes sharply. What is the outdoor test environment like?

[moiz_elec]

Hi Robin,

The sensor is located near Paris 2 meters high. The PTFE filter is almost fully surrounded by air. Indeed, we found a correlation between quick temperature changes and humidity weird values (see attached screenshot - temperature in red, humidity in blue).

We also made antoher test, artificially increasing the humidity indoor at stable temperature. In this case the sensor does not deliver the same weird peaks as outdoor but his humidity value cannot exceed 60-65% whereas another sensor was giving us >80% RH.

[moiz_elec]

I can add that we use energy harvesting thus our I2C bus is not supplied continuously and the sensor is always :

Powered up -> Configured -> Forced measure -> Powered down

at a rate of several minutes to several hours.

[BSTRobin]

Hi moiz_elec,

Did you have the raw data which you collected and provide it to us? we want to check the detail of temperature data and humidity data.

What is about the humidity range for ourdoor environment?

Information from humidity data 2 picture.

INDOOR

• Temperature range 18~22℃
• Humidity range 50% ~ 25% rH

OUTDOOR

• Temperature range -6~10℃
• Humidity range 0%？ ~ 30% rH (not including peak value)