Battery discharge curve

[JF002]

Schematic suggests a single colour LED, dunno what colour, so no dual colour indication there!

http://files.pine64.org/doc/PineTime/Pin...191020.pdf

If there is an LED, it is not visible from the outside. I tried to toggle pin 27 and saw nothing...

Conceptually, it just measures the voltage using the ADC on pin 31 (AIN7) with the following settings:

• reference voltage: internal (0.6V)
  
• gain set to 1/5
  
• positive/negative channel resistors bypassed
  
• acquisition time 3µs
  
• single ended mode
  

Thanks @ayke  for these info, I've successfully measured the battery voltage with these.
I've measured max voltage of more than 4v, a bit more than what you show on your graph.

How should we use your discharge curve to display the battery level in % ? For now, I implemented a simple linear interpolation between 3.9v and 3.55. Anything above 3.9 is 100%, anything lower is 0%. Is there a smarter way to process the voltage?

Thanks!