Each time you power on the headphones, the voice prompt announces the headphone battery charge level, and the battery indicator on the inside of the right earpiece glows for 10 seconds. Also, when you press any of the headphone controls, the battery indicator glows for 10 seconds
While the headphones are in use, the battery indicator blinks red when the battery needs charging
If you are connected to an Apple device, the device displays the headphone battery charge level near the upper right corner of the screen