Checking the remaining battery charge | Bose QuietComfort Headphones (2nd Gen)

Battery Status

Indicator light	Battery level
Solid white	Medium to full charge
Solid amber	Low charge

You can also check the battery level using the Bose app.

Battery level

When the headphone battery is low, you hear the following tone: 

Charging Status

Indicator light	Status
Solid amber	Charging
Solid white	Full charge