M5core Ink battery duration

  • Hi,

    I am planning to use the M5Core Ink as a temperature sensor, but the device runs out of battery after about 12hrs or so even using m5.shutdown . (my goals would be 6 months+ of lifespan)

    To get a standard example, I used the M5core Ink NTP project (https://github.com/hpsaturn/m5coreink-ntp-clock) that seems well known to compare with others.

    I am charging the battery for 6 hours before running on battery.
    With the default 1 minute shutdown and using RTC to wake the device up, the battery still does not last more than 12 hours. The device is only staying up a couple seconds to getRTC, and should go back in deepsleep through shutdown. I tried longer shutdown (5min), but that did not increase the battery life even though I could see that clock was refreshed only every 5 minutes.

    Using https://www.digikey.com/en/resources/conversion-calculators/conversion-calculator-battery-life for battery duration, the battery being 390mAh and device using 0.0025mA (according to https://www.gwendesign.ch/kb/m5stack/m5coreink/) in shutdown, I should expect months at least.

    Has anyone data to compare or recommendations?

    Thank you

  • @eddie2070 interesting. Once you've collected the temperature, what are you doing with it? Just displaying it? or are you sending it via WiFi?
    I don't have a temperature sensor, but I'm going to try on my side with a ultrasonic sensor and see how long it works.

  • @eddie2070 said in M5core Ink battery duration:

    With the default 1 minute shutdown

    Is the M5.shutdown() command working for you? Is it really sleeping for 1 minute? In my case, whatever delay I specify it sleeps for ~5 seconds no more!

    If you have the same issue, that could explain why you have battery duration issues ;-)

  • @eddie2070 ok - got the answer for shutdown(): it only works when powered from battery. So, I've created a small test program that just displays an image + counter, then shuts down for 1 hour. I'm going to see how long it lasts...

  • My battery duration seems longer: the program I ran Tuesday is still running "more or less". By "more or less" I mean that sometimes I find the M5 with a black screen, and I have to press the POWER ON button to wake it up. I shouldn't need to do that, so this strange. But at least with the counter displayed on the screen, I know my program ran for 72 hours (indeed more or less 3 days).

    Difference with yours:

    • I do not connect to a Wifi / Internet (which usually consumes battery quite a lot)