We sought out power banks weighing 8 ounces (half a pound) or less, making them easy to carry around in a wallet, pocket, or bag. We preferred power banks rated for at least 2,000 mAh and up to 10,000 mAh capacity, which tells you roughly how much battery life they hold. Checking for safety features such as overcharge protection and build quality is also important. The lightweight design, reasonable price, and helpful LCD. After putting in hundreds of hours of research and testing, we've found that the Belkin BoostCharge Plus 10K is the best power bank to charge a phone, tablet, or another small, handheld device. To find the best power bank out there, I tested more than 60 portable chargers and batteries from big brands like Anker, Belkin, UGreen and Mophie — as well as from smaller players such as Biolite.