AirMeter.io has been optimised for low power battery operation using power profiling equipment to achieve extremely low power consumption on the ESP32 family of microcontrollers.
Sensor Optimisations
Advanced low power CO2 sensors generally support a sequence along the lines of
- Enable
- Wait
- Read
- Disable
This has been implemented for the Senseair Sunrise sensor and will also been included in the integration of any additional sensor families which support this feature.
Connected To Wifi
In many cases AirMeter.io is intended to be used connected to a wireless network. Therefore by using a Nordic Power Profiler Kit II and leveraging some advanced ESP32 platform features a power draw of 5mA has been achieved in this mode.
Tests were performed using a LilyGo 2.13 ePaper Display ESP32 board. The readings and contents of the ePaper display updated once a minute.
These results translate to 15 days of runtime whilst fully connected to wifi and updating readings using a 1800mAh battery.
Disconnected Mode (Planned)
When using very low power sensors whilst the device is connected to wifi most of the power usage is maintaining that connection.
Therefore a "disconnected mode" for when the device is away from or does not require connectivity will allow for substantially longer periods without a charge.
This mode will be able to utilise other power management features such as deep sleep since connections do not need to be maintained.
Remote Monitoring Mode (Planned)
This is an extension of disconnected mode where the device is being used in a remote monitoring/data collection scenario with centralised logging via MQTT.
In this mode the device will wake up on a scheduled interval, connect to wifi and publish readings that have been taken.