VIN 5V question

New to developing on the Electron. When it is plugged in with USB is the VIN pin automatically outputting 5V when running? Or do I need to set a pinMode for it?

Vin is not a GPIO but a hard wired connection with a Schottky diode for protection against backfeeding.

See here
https://docs.particle.io/datasheets/electron/electron-datasheet/#block-diagram
and here

https://docs.particle.io/datasheets/electron/electron-datasheet/#pmic-power-management-integrated-circuit-

Ahh i see, so when USB is plugged in and battery is charged, VIN will output 5V

Even without the battery being full or even attached Vin will output 5V (Vusb - 0.2V to be exact).

@DarrenD, to be clear, the battery does NOT supply any voltage to Vin, so charged or not charged, as @ScruffR said, the voltage will be as he indicated.