M-SoM + Muon battery weird behavior

Firmware
1

I'm running a very basic firmware that sleeps all the time (ULTRA_LOW_POWER), and sends device vitals to particle cloud every hour (just for testing by the moment).

Setup:

  • M-SoM(M524) + Muon
  • LiPo battery (the one that comes with Muon kit)
  • DeviceOS 6.3.2
  • USB-C to USB-C wire (the one that comes with Muon kit) connected to laptop when charging

I'm experiencing strange behaviors regarding battery charging, like:

  • If device is power plugged (USBC wire to laptop), the charge led is not lighted on (or it lights for some minutes and then lights off again). If I unplug and plug the USB-C wire then charging led lights on again for short time
  • Battery seems not charging while sleep

I have retored tinker app to device, to check its behaviour, and I see that battery is charging, but charge led is off all the time.
If I request last vitals from web console, I see that the battery is charging, but charging status reports that battery is already "charged":

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Is there any open issue or regarding this?

2

If device is power plugged (USBC wire to laptop), the charge led is not lighted on (or it lights for some minutes and then lights off again). If I unplug and plug the USB-C wire then charging led lights on again for short time

This is the normal behavior. Once the battery is fully charged, the charge LED goes off.

If you disconnect the battery and reconnect it, an attempt will be made to charge it, because it can't know if it's the same battery or not, but eventually the PMIC will determine that it is fully charged again, and the charge LED will go off.

The charging is controlled by the PMIC (bq24195), which controls the LED as well. It runs constantly and is not aware of the sleep state of the MCU. Whether it charges or not depends on the charge state of the battery, the voltage in, and on the Muon, the temperature sensor in the battery.

Charging could also be disabled in software from the MCU while awake. This happens when you disconnect the battery. There is an edge case where if you plug a battery in while asleep, it won't be detected or charged until the device is woken again to turn charging back on.

3

Thanks. I understand this applies to the situation with a full battery.

In my case, battery is almost empty. But, when connected to the power, I can see that the battery is charging, but charging led is off, and reported status is "charged" instead of "charging" (you can see it in screenshot from previous post). Eventhought battery keeps on charging.