When you need a portable battery that isn't bothered by the elements, check out this Rayovac Weekender Mobile Device Charger. Its rugged case makes it waterproof and dustproof, and it's drop tested so you can rely on it giving you the power you need. It has 2 USB ports—a 2.4A and a 1.0A—so you can charge 2 devices at once. A must for camping or to have on hand when there's a power outage.
Weight: .66 pounds
Batteries Charged Simultaneously: 2 (max)
Battery Chargers: Automatic Shut-Off, Dustproof, 2 USB Ports, Waterproof, LED Charge Indicator Light
Includes: Micro USB Cable
Estimated Charge Time: 4 hour
Volts Required: 120.0 Volts
Electronics General Compatibility: Most USB Devices, Most Mobile Phones, iPad Tablets, MP3 Players, iPhone Cell Phones, Digital Book Readers, Bluetooth Headsets