MH Z19b - Running CO2 sensor on batteries

[Siddharth Velappan]

I'm trying to run the MH Z19b CO2 sensors interfaced by a PIC microcontroller, powered by 3.6V batteries.
I would like to get the most out of the battery life. So, I have used a transistor and a GPIO pin from PIC to control the power supply to the CO2 sensor programmatically.

Please find below, the pseudo code of the programming logic I had used to take CO2 measurements from the MH Z19b sensor. I would like to know if this logic will provide me valid measurements. I am trying to measure the CO2 concentration once in every 15 minutes.

start_PIC();
while(true) {
    MHZ19_power_on();
    PIC_sleep(120 seconds);
    /** Till 120 seconds, CO2 sensor was giving 400ppm and only after that I started getting realtime values **/
    MHZ19_get_CO2_concentration_value();
    MHZ19_power_off();
    PIC_sleep(900 seconds);
}

[alowhum]

These type of sensors often have a warm-up time, often measured in minutes. The datasheet will tell you. If you don't let it warm up you will get poor readings.

[bitttttten]

Hi @Siddharth-Velappan

The warmup time of the MH Z19b is 3 minutes. So 2 is probably fine, but you could probably do 3 just in case. Although 2 would save your more battery time.

Do you mind explaining your setup a bit more? I would love to do something similar but I do not know where to get started with the PIC microcontroller!