BME688 stability flux

[larsmats]

Dear board,

Running several of the BMA688 sensors for several months I notice apparently random, days-long spikes in Co2/Iaq/bvoc baseline values, which I cannot correlate neither to time, environmental or other units running the same sensor. Also it does not correspond to iaq-accuracy, run-in-status or stabilization status values. The graph below shows one sensor behaving nominally (i guess - in green) reporting co2 and one at the same location reporting strange peaks in co2.

Both sensors run the 300s / 28d / 3.3v configuration.

Any ideas where to start looking for the cause?

Among our own theories would be the possibility that a particle may have enterred the sensor, which could be physically possible, but seems a bit far-fetched as the device is in a housing.

Thanks,

Lars

[BSTRobin]

Hi larsmats,

In what environment were the two sensors used?

[larsmats]

Hi BSTRobin,

They are mounted next to each other in our office canteen - each day there is an expected peak at around 12 noon, except for during weekends.
It is a professional office environment otherwise with filtered air conditioning, essentially as could be expected in a relatively modern lab,
We are long-term testing our devices to ensure stable operations (over several months). We have several more in the same envionrment but we see a few other instances of these peaks on our other sensors, at different times.

Since I wrote to you we upgraded our firmware to include the BSEC 2.4.0, but I see no mention of similar behaviour in the release notes.

Thanks, Lars

[BSTRobin · Accepted solution]

Hi larsmats,

What sensors are used for the CO2 data corresponding to the green line? Do you mean that the data corresponding to the blue line is the BME688 sensor?

How do you ensure that both sensors are in the same environment?