SCD41 in a Beehive

[madlan]

Hi, I have one of your SCD41 Co2 sensors which I would like to add to a beehive - how would this affect the calibration?

On the guide page it states:

“These sensors also feature automatic self-calibration routines to automatically adjust to their sensing environments over seven day calibration period. For best results, Sensirion recommends taking continuous readings for at least one hour a day of ‘fresh air’ for the calibration period to complete.”

Does this mean I can leave it outside for 7 days running to calibrate and then it’s ok in the beehive permanently or that I need to take it out for an hour a day in fresh air?

The Beehive will be accessed one a week at most so I’m guessing the readings will be off?

Thanks

Alan

[paulvha]

according to the datasheet : https://sensirion.com/media/documents/4 … asheet.pdf, chapter 3.7 : Automatic self-calibration (ASC) ensures the highest long-term stability of the SCD4x without the need of manual action steps from the user. The ASC algorithm assumes that the sensor is exposed to air with CO2 concentrations of 400 ppm at least once per week.

[madlan]

I just gave the datasheet to chatgpt and described the situation.

I will open the beehive once a week March to September so can place the sensor clearly exposed to the atmosphere (421 ppm) which should help the ASC. I don’t think it’s worth doing the forced calibration, I think 15 minutes or so exposed should be enough.

"To ensure accurate readings from the Sensirion SCD41 sensor inside your beehive, considering it will rarely be exposed to outside air, you need to address the automatic self-calibration (ASC) requirements stated in the datasheet.

Key Points from the Datasheet:

ASC Algorithm: The SCD41 sensor includes an automatic self-calibration (ASC) algorithm that maintains long-term accuracy. For proper functioning, the sensor must be exposed to air with a CO2 concentration of 400 ppm at least once a week .

Accuracy Drift: If the ASC is not properly utilized, the sensor may experience an accuracy drift over time. The maximum drift after five years, with proper ASC, is ±(5 ppm + 2% of reading) .

Recommendations:

Weekly Exposure to 400 ppm CO2: Since you will only be opening the beehive once a week from April to September, you must ensure that during these openings, the sensor is exposed to ambient air with a CO2 concentration of approximately 400 ppm. This exposure is crucial for the ASC to function correctly.

Simulating Outdoor Air Exposure: Outside the period of regular hive openings, consider creating a mechanism to simulate the required weekly exposure to 400 ppm CO2. This can be done by:

Opening the Hive Briefly: Even outside your regular maintenance period, open the hive briefly once a week.

Artificial Exposure: Use a controlled environment or a device to expose the sensor to 400 ppm CO2 weekly. This could involve placing a CO2 source with known concentration near the sensor.

Monitor and Adjust: Regularly monitor the sensor’s readings and calibration status. If you notice significant deviations, perform a forced recalibration using an external CO2 reference value as described in the datasheet .

Environment Control: Ensure the hive’s internal environment is stable and that the sensor is not exposed to rough handling or extreme conditions that might affect its accuracy.

By implementing these steps, you can maintain the accuracy of the SCD41 sensor within your beehive, ensuring reliable data collection throughout the year."