Power Management
Battery + USB Power
We wanted to make the Feather easy to power both when connected to a computer as well as via battery. There's two
ways to power a Feather. You can connect with a MicroUSB cable (just plug into the jack) and the Feather will regulate
the 5V USB down to 3.3V. You can also connect a 4.2/3.7V Lithium Polymer (Lipo/Lipoly) or Lithium Ion (LiIon) battery
to the JST jack. This will let the Feather run on a rechargable battery. When the USB power is powered, it will
automatically switch over to USB for power, as well as start charging the battery (if attached) at 100mA. This happens
'hotswap' style so you can always keep the Lipoly connected as a 'backup' power that will only get used when USB
power is lost.
The JST connector polarity is matched to Adafruit LiPoly batteries. Using wrong polarity batteries can destroy
your Feather