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Tech review: The best portable USB battery pack for daily use

Tech review: The best portable USB battery pack for daily use

This post was done in partnership with The Wirecutter, a buyer’s guide to the best technology.

Smartphone batteries don't always last through a busy day, but a pocket-size USB battery pack can give your handset enough of a boost to survive the evening. After 40 hours of research and 65 hours of testing, the one we like the most is Anker's 2nd Gen Astro 6400. It fits in any pocket or purse, and it charges phones and small tablets about as fast as any pocket-friendly pack out there. At 6,400 mAh, a measurement of battery life, it has a larger...

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