Power a Raspberry PI with the Mavic Battery

I've tried powering my Raspberry PI with several generic and cheap cell-phone charging battery packs. They either don't provide a steady voltage (causing instability), or don't last very long.

However, the Mavic Battery + Battery Bank Adapter seems to run the Raspberry PI all day. I've had it going (running a Plex server) for 11 hours now, and it's only used 25% of the battery.

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