Is your phone, tablet, or laptop typically in the battery red zone before the day's end? These portable chargers and power banks give you the most boost when you're out of juice. I’m a Mobile ...

Listen up: We tested 15 AA batteries—the type typically used ... and repeating the cycle until the batteries die. Battery life was 7.3 hours for an Energizer, 6.8 hours for a Duracell, and ...