Sony NWZ-A815 Operation Manual page 85

Adjust data format and bit rate
Playing time will vary, as battery charge can be affected by the format and bit
rate of songs, videos or photos that are played.
For details on charging time and usage time, see
(jr
page 120, 121.
• Do not leave the player connected for extended periods to a laptop computer that is not
connected to AC power, because the player may discharge the computer's battery.