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