Hi! I use couple of boards (also testing custom builds with Wemos LoLin32 Lite and SX1278 LoRa Ra-02) but in this case for testing i use new version of Heltec board - i can confirm that it is new version because voltage sensing is on pin 37 (not 13). About voltage made one more test:
battery voltage - 4.13V
log with battery attached:
08:51:58 122 [Power] Battery: usbPower=0, isCharging=0, batMv=2249, batPct=0
serial log without battery:
??:??:?? 42 [Power] Battery: usbPower=0, isCharging=0, batMv=2584, batPct=0
Have to admit that readings are strange. I’m not engineer but did you take a look into that code that i posted with working code for battery charging for heltec? (Heltec Board is deep discharging batteries? - #12 by liniany)