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!

Hi- following up on Boron CAT-M1 EtherSIM (BRN402/404, not BRN404x) charging issue / question. Based on further testing, it seems like the Boron is working (charging) as designed, w/ proper PMIC function and charging regardless of being in ULP mode (and w/o having to be placed in DFU).

Rick, specific responses to your questions:
1.) CHRG LED turns on appropriately on all devices when charging
2.) no PMIC setting adjustments
3.) tried w/ wallplug, laptop USB, portable charger; USB 2/3 (not USB-C/PD)- all charge appropriately*
*Tested w/ an in-line USB VA tester, voltages (~5V) and currents (0.03-0.8A) depending on battery state / capacitance)

I think the apparent issue arose from operator error, i.e,. me :frowning: The system setup has an in-line JST power switch from Adafruit ( / product / 1863) between the Boron JST LiPo connector and the LiPo battery. So potential states would be:

NO USB power / charger → JST power switch OFF → LiPo battery
-does not power on; no charging (appropriate)

NO USB power / charger → JST power switch ON → LiPo battery
-powers on from LiPO; no charging (appropriate)

USB power / charger → JST power switch OFF → LiPo battery
-powers on from USB; no charging (because of power switch)

USB power / charger → JST power switch ON → LiPo battery
-powers on from USB; LiPo charging via PMIC

I had been testing device charging w/o rigorously monitoring the level of LiPo battery charge or state of the JST power switch, so the issue of the appearance of non-charging likely resulted from my not noting that if the JST power switch was set to OFF (to place device in storage / non-deployed state) while the USB power / charger was plugged in (regardless of how charged the LiPo battery was), deviceOS readings of battery charge (from FuelGauge) would not be reflective of actual LiPo charge (and thereby potentially indicate unsuccessful or incomplete charging).

All seem to be working now, so will update any changes. Appreciate help! :slight_smile:

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