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USB power banks offer peace of mind when your battery is dead or close to dying but you don’t have access to a wall outlet. After nine hours of research and 30 hours of testing, we’ve found the best USB power banks to meet a wide range of needs—whether you’re looking for a backup boost of power or something that will keep your phone or tablet fully charged for days at a time.
The TravelCard Charger is the best option for someone who wants an emergency boost of power that’s always on hand. It has the lowest capacity of any power bank we tested—it can charge most phones to only around 30 to 50 percent from empty—but it’s unmatched in terms of weight (exactly 2 ounces) and size. It’s bigger and thicker than the average credit card but not by much; it easily fits in a wallet or pocket. It has a built-in USB-A cable to charge it up and a built-in output cable (either Lightning, Micro-USB, or USB-C, depending on which version you need) to top off your phone or another handheld device with a little boost of power.