Grace Digital GDI-BTPB300 3play Quick Start Guide - Manual (Page 8)

3.4 Battery charging
When connected to external power source via either a USB connection to a computer or to the
supplied AC adapter, 3play will automatically charge the built-in rechargeable battery.
It is suggested that you charge the 3play completely prior to your first time use on battery power.
It will take proximately 2 to 3 hours to completely charge the battery.
Note:
● The built-in battery charges while 3play is playing audio and plugged into an external power
source
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