SCD30 CO2 calibration?

Sensors Environmental
1

Anyone have any experience with the SCD30 CO2 sensor? I’ve been trying to calibrate it, but it seems to read high when placed outdoors. Outdoor background CO2 concentration should be around 400 ppm, but I consistently read in the low 600s in my backyard. Either Austin, TX is more than 200 ppm over background (and I’m not even close to the center of the city…), or something else must be wrong.

Anyone have any typical measurements they can share?

2

Hi jeremybillheimer,

Have you adjusted the settings using [this example to calibrate the sensor for your environment? The default settings for altitude and pressure are for Boulder, CO so you’ll need to adjust those for Austin, TX if you have not done so already.](SparkFun_SCD30_Arduino_Library/examples/Example2_SetOptions/Example2_SetOptions.ino at main · sparkfun/SparkFun_SCD30_Arduino_Library · GitHub)

3

Hi Mark,

I’ve set altitude to 175 meters (which is about right for Austin), and 1020 mbar for our current conditions. Still reading about 600 ppm outside.

I have a second sensor that I will try sometime next week.

4

Hi Mark,

I’ve set up a second sensor. Both are outdoors in the same location. One reads approximately 590 ppm, the other reads approximately 480. This is well outside of the accuracy spec of the part.

5

How long have both been running? Sensirion recommends 7 days of continuous readings with at least 1 hour a day of ‘fresh air’ for self-calibration to complete.

6

Hi Chris,

I’d found on previous attempts that the first sensor wouldn’t budge when doing the 7 day calibration. Not sure why.

That being said, I’m think I’m good now. What I did this time is set a forced recal on both sensors to 408 ppm, and then restart the 7 day cal. The 7 day cal is still on going, but I am already getting much better correlation between the two sensors, and they both approach true background.

I’m not entirely sure what the root cause was, but they both seem to be working now, and I’m satisfied with the results.

Thanks for the help!

-J

7

I am working with my Sensiron SCD30 sensors and wish to know how you did a forced recalibration to 408 ppm?

Regards

8

That is done with ```
airSensor.setForcedRecalibrationFactor(408);


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