Hi folks, was hoping to jump on this with a related question and drain the knowledge from more experienced people than myself 
In regards to the battery pins on the back of the board, are they solely connected to the usb port for charging and nothing else? If that’s the bizarre situation that was described above I’m assuming that’s the problem I have that connecting a battery to those pins does nothing, board doesn’t boot. I’m aware the led is solely for charging notification and no help to me but when I connect battery to the two pins on the back I get nothing from the board at all (should send a temperature every 30 seconds to a mqtt broker for testing) can’t even see it on the wireless network.
If I connect the battery to the 5v and GND pins it works no problem but my lack of experience has me worried it will work well until it all combusts and burns my house down.
I have an adafruit minilipo charger that I can connect the pass through to the 5v and GND and the battery to the charger so that I can charge the battery when needed and power the esp32c3 from which ever is available but I wanted to check that this was correct as the whole situation seems completely mad to me.
Also trying to get voltage reported back, have been using d0 and will change to d3 as per previous advice, currently reporting 0 battery but will see what happens on d3 instead.
Using a lipo 3.7v battery fully charged and reporting 4.1v from terminals.
Works perfectly when connected to usb and also seems to work (except battery reporting) when powered from battery connected to 5v and GND pins.
Hoping to have this running on battery with easy to charge option. AI calculations estimate 170 days +/- per charge when deep sleep and waking every 15 mins for for temp reading.
Hoping someone can help, thanks for reading if you got this far 
Edit: apologies for emojis, I am old.