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We replaced the AC/DC wall plug with a unit that outputs 15V.
Installation
So, we added a buck converter to the input which drops the voltage to 12.6v to charge the battery and power the speaker. This buck module was simply hot glued to to the bottom of the board.
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A switch was added to isolate the battery to prevent parasitic draining of the battery over time.
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And voila, all done and running on battery and it sounds amazing!
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