Denon AH-GC20 - Manual (Page 7)

Charging
When using the headphones for the first time after purchase or when the
remaining battery is low, connect the headphones to a computer or a USB
to AC power adapter (not included) using the supplied USB cable.
.
or
The Charge/NC indicator blinks during charging. It takes approximately 3
hours to charge the headphones. (The duration time differs depending on
the charging output.)
.
ON
OFF
100 % charged : Lights red
50 - 99 % charged : Blinks red at 2-second intervals
0 - 49 % charged : Blinks red slowly
0 You can connect the headphones to a device using the supplied audio cable to
enjoy listening to music even if the batteries are drained. (v p. 20)
0 The headphones can be used for approximately 20 hours of music playback when
fully charged.
0 You can listen to music from a paired Bluetooth device or make phone calls even
during charging. In this case, noise may occur in the audio from the headphones
depending on the type of computer used.
NOTE
0 When connecting the USB cable to the charging port, be sure to match the cable
connector with the shape of the socket. Forcing the connector into the socket will
cause damage.
0 A rating of the charging output should be DC 5 V, 2.4 A or less.
0 The usable time of the headphones differs depending on the temperature of the
environment in which they are used and method of use.
0 The power turns off when the USB cable is connected to the headphones during
use. Turn on the power again to continue using the headphones.
0 If the usable time of the headphones is extremely short even when fully charged,
the battery may have reached the end of its lifespan. In this case, please contact
the Denon Customer Service Center (see the back of this manual).
0 You cannot change rechargeable batteries yourself.
Contents Preparation Connections Operation Troubleshooting Appendix
7