If you have plans to camp or travel this summer then a must-have device is he Mophie Juice Pack Powerstation Pro. It is an external battery that can take a beating and charge nearly any USB-powered device. Its rugged design and large capacity can add more than a full day of 3G talk time to an Apple iPhone 4S
The bottom edge houses a full-sized USB port and micro USB port and a single button along the side enables the battery indicator lights. With a 2.1-amp output, the Powerstation Pro can charge a wide variety of devices including iPhones, iPads, and most other USB-powered devices.
The Powerstation Pro has a large 6000mAh battery and it has shown in some tests to add an impressive 24 hours of talk time to an iPhone 4S. It is IP65 rated, which means it is dust and water resistant when its ports are closed. $130