LiPo battery charging while in ultra-low-power (ULP) on Boron

Hi all- posting because trying to figure out how the (Boron) PMIC works (or doesn’t) during ultra-low-power state (ULP) w/ respect to charging an attached (LiPo) battery?

I have setups w/ Boron CAT-M1 EtherSIM (BRN402/404, not BRN404x) running deviceOS 4.0.0 and powered solely by 3.7V LiPo battery- each device turns on, calls home once a day at a set time, then goes into ULP mode after 10min*, can get ~200+ boot-ups/connections per charge on a 2500mAh battery.
*given recent cellular service minimum connection intervals 11/2022

Using a typical wallplug / portable microUSB charger (1A / 2.1A / etc.) connected to the Boron microUSB connector, I’m noticing that there is no (or ? minimal) re-charging of the 3.7 LiPo battery (attached via LiPo JST connector) while the Boron is in ULP sleep mode. Since the overall setup is configured to minimize time in a fully-powered/“on” state (and w/o the option for continuous wall power), I’ve circumvented this by intermittently placing the devices manually (using reset/mode buttons) in device firmware upgrade (DFU) mode and charging only while in that state (i.e., setup is offline/charging) for several hours.

Is this how Boron power management should be working (i.e., LiPo battery charging and/or PMIC is disabled/off in ULP mode?), and if so, is there a way to circumvent the inability to charge?

Appreciate any input!

The Boron should be charging when in sleep mode.

  • Is the CHRG LED on?
  • Are you changing the PMIC settings at all?
  • Does this happen if you are plugged into a computer vs. the charger?

I suspect that your charger does not support DPDM and the Boron is incorrectly determining that the charger is very low current (100mA) and not enabling charging.

The easiest way to debug this is to run the Web Device Doctor as it also outputs PMIC debugging info.

will test ASAP and update!