Build tested on RAK4631 with battery and their solar panel box.
This is from the log:
17:40:30 102 [Power] Battery: usbPower=0, isCharging=0, batMv=4164, batPct=96
Note that mV reading and Pct is ok.
It does not detect being connected to USB and charging.
Also tested on TBEAM where it seems to be ok.
There still seems to be a problem with the FW for this board that it goes to
sleep for ever after running for a few hours.