Powering BeagleBoard by Battery

Hi all,

I am working on Beagle Board to develop an application that measures
audio signal from any electronic gadget (like PC, Playstation,
smartphones, etc.,) and records it continuously from audio in port of
the board. The Beagleboard also sends the output audio to a headphone
through audio out.

The device using Beagleboard needs to be active for at least 20-24
hours and also needs to be portable, ie., needs to be battery power
supplied. And after having a glance at the OMAP3530 datasheet and also
the Beagleboard system reference manual, it takes typically around 350
mA with just the processor and key components in action without any
peripherals. This means for my requirement of 20-24 hours, I need a
8500 mAh battery to power the board.

The question that I have is how can I interface a battery pack
(rechargeable) to the BB? Is it through the OTG USB port or is there
some other way of interfacing a battery pack to the board? Also, it
would be helpful if someone can share their knowledge on a good
battery pack with the requirements as mentioned above as I am trying
to find one as well.

Would this work? (Just googled around)