Best known by its APC initials, American Power Conversion has been selling spare batteries and other power accessories for years—typically large items that you’d never expect to toss into a pocket. Roughly iPod-sized and made from glossy black plastic with a single chrome button, the company’s new Mobile Power Pack UPB10 ($70) changes all that. It’s a 10 Watt-hour battery with two USB ports on its top, one a mini-USB port designed…
