Datasheet
Since the ESP8266 does not have multiple ADC pins, we didn't want to 'sacrifice' one for Lipoly battery monitoring.
However we do have a tutorial that mentions how to do it, using two resistors. You can check out the wiring diagram
here (use the VBat pin to measure) (https://adafru.it/jCY) and the code here (https://adafru.it/jCZ).
ENable pin
If you'd like to turn off the 3.3V regulator, you can do that with the EN(able) pin. Simply tie this pin to Ground and it will
disable the 3V regulator. The BAT and USB pins will still be powered
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