iWalk’s new Duo 3000 ($25) is a smaller, less expensive, lower capacity version of the company’s Extreme Trio 10,000 battery. Like that battery, Duo 3000 also includes a built-in Lightning cable and micro-USB cable. A short, separate micro-USB cable is also included for recharging the battery — a micro-USB port can be found on top of the battery, along with a power button. The front of Duo 3000 has a small blue status light, and the…