Released today, the Third Rail iPhone 4 case from Third Rail Mobility takes a fresh look at the issue of smartphone battery life. The case is designed to be as compact and dynamic as possible, the only additional real estate present in comparison to a traditional case is a small nub of circuitry on the docking end of the phone. This smart circuitry, combined with their smart batteries offer a superior level of control and customization when it comes to mobile charging.
Unlike most case/charger combos the Third Rail system does not incorporate a built-in battery. Instead, the ultra slim case has a dock on the back where the user can swap super light weight batteries—only 1.4 ounces—in and out, or stack a number of batteries for as much charge as is desired, allowing for the case to always remain on the phone. If you have multiple batteries attached, the intelligent charging system can determine which has the most charge and will transfer power from other batteries to the one it determines to be a primary battery, always guaranteeing you have one fully charged brick. Additionally if you have several batteries attached you can plug the whole unit in and simultaneously charge all the batteries and your iPhone.
Since the batteries are swappable you never have to worry about the system becoming obsolete with each new smartphone purchase. The batteries will work with all cases offered by Third Rail, including future ones, to reduce waste and consumer cost. Each battery also contains its own built in micro USB port so it can directly charge any micro USB device independently or while strapped to your iPhone.
The system can be purchased from their site for $90 which includes an iPhone 4 case and one battery.