- Background
- Auto Calibration Mode
- Case in point: the experience from t******
- Manual Calibration Mode
- Video Demo
Background
The SCD40 sensor used in the sensor is a good reliable sensor, but due to the constant contact of the air sensor with the air, it can lead to reading errors after transport, partly due to the confined air and bumps on the road.
If the sensor still shows readings above 1000 ppm after being activated and left to stand for more than 3 minutes in a well ventilated environment, it may indicate that the sensor needs to be recalibrated.
Auto Calibration Mode
In the current firmware, the SCD40 sensor's auto-calibration feature is enabled. The auto-calibration cycle lasts approximately seven days, and the calibration is based on extrapolating a new zero reference based on the lowest CO2 concentration data over a seven-day period and adjusting the sensor's measurement accuracy. This process requires the sensor to experience at least approximately one hour of open window ventilation over the course of a day during normal operation to ensure that it is exposed to a low CO2 concentration that approximates the outside environment for accurate auto-calibration.
Case in point: the experience from t******
The sensor reads above 4000 when received and returns to normal from a certain point after remaining stationary and some attempts.
I don't know what triggered it, but it seems to have started to show normal CO2 ppm. I'll tell you what I did after that. (I'm sure I did pointless things...) -Left it by an open window for a few minutes -Blowed into the sensor to check the maximum value -Try running it outside for about 30 minutes using a mobile battery -Left it by a vent that is constantly supplying air from 18:30 -00:25 Confirmed that it started to show normal CO2 ppm
Manual Calibration Mode
In the current Beta firmware (V240512_1), a forced calibration service is provided. The procedure is as follows:
1. Place the sensor in a very well ventilated environment, e.g. outside a window, ensuring that it has access to plenty of fresh air.
2. Switch on the sensor and leave it to stand for more than 3 minutes (longer standing time is recommended to ensure stability).
3. Using the sensor calibration service in Home Assistant (HA), enter a close CO2 value (since there is no comparison sensor, it is recommended to enter a hypothetical value between 450-500 ppm).
4. Click the Calibrate button to complete the forced calibration.
This method can help the sensor quickly regain accuracy without going through a full auto-calibration cycle.
