When the headset is powering on, the red LED flashes rapidly indicating the battery level.
4 flashes = High, 70~100%
3 flashes = Medium, 30~70%
2 flashes = Low, 0~30%
Voice Prompt Indicator
When you power on the headset, keep pressing the Jog Dial and the Phone Button simultaneously for about 5 seconds until you hear high tone triple beeps. Then you will hear a voice prompt indicating the battery level is high, medium, or low.