Checking the remaining battery charge | Bose Bluetooth headset Series 2

To determine the remaining battery charge level, turn the headset on and locate the battery light on the side of the headset. If the headset is already on and no lights are lit, press any button on the headset to activate the Bluetooth® and battery indicators, as they turn off after 10 seconds of inactivity to conserve battery power

• A green light indicates that 1½ to 4½ hours of talk time remains. The headset has more than 30% of charge remaining
• A yellow light indicates that 10 minutes to 1½ hours of talk time remains. The headset has approximately 30-5% of charge remaining
• A flashing red light indicates that less than 10 minutes of talk time remains. The headset has less than 5% of charge remaining
• If no light appears after pressing a button to activate the battery indicator and the headset is on, it has less than 2% of charge remaining

For more information, see Understanding LED indicator status lights and information.