How can i charge my Sony Walkman NWZ-E474 if there isn't enough current?

This question is directed at any experts on electrical current: Allow me to explain the scenario- at my workplace I would like to use a Sony Walkman NWZ-E474 to play music throughout the building's speaker system. The aux cable to connect to the speaker system is located upstairs in a room where there... show more This question is directed at any experts on electrical current:

Allow me to explain the scenario- at my workplace I would like to use a Sony Walkman NWZ-E474 to play music throughout the building's speaker system. The aux cable to connect to the speaker system is located upstairs in a room where there isn't any mains nearby, so my only way to charge the Walkman is through a USB socket on a large projector unit of some sort which does work but only gives out a very small current, not enough for the Walkman to draw power from. I want to keep this Walkman permanently in that place and permanently playing music 24/7.

Is there anything I can do to ensure this Walkman's lithium-ion battery doesn't run out of charge every 30 hours and is just permanently on?
Is this sustainable for the battery?

Sorry if this question is confusing, i can reiterate parts if needed.

Thanks!
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