The biggest problem with the iPhone? Low battery life. But personally, iPhones are something that we depend on daily, a great device which can do practically anything (with proper apps). However its main Achille's heel is that it has a small battery capacity, hindering our ability to take advantage of all of the apps and features our iPhone offer us. This is where a battery pack add-on comes into play...
At the same time you're charging your player's internal battery, you're also charging the detachable Reserve battery pack for your iPod or iPhone. It's like getting twice as much use out of every time you charge. This device for great for USB-rechargeable devices, including iPod, iPhone, and other phones and MP3 players. PowerBlock works in almost any 100 to 240 volt AC wall socket, and delivers safe power levels for iPod, iPhone, MP3 players, and other USB devices. It's so small, that you can take it with you (it's small enough to fit in your jeans coin pocket). The Reserve battery snaps into the Dock Connector of your iPod or iPhone, adding hours of additional use. No more worrying about battery life; no need to lug your original, big charger along with you.
Mini Battery Pack
This unit extends your play time up to 15 hours of music; 4 hours of video; 3 hours of talk. Includes a retractable USB charging cable to recharge the battery pack, has a rechargeable lithium-ion polymer battery pack for increased energy efficiency. Small enough to keep it connected to your iPhone or iPod while is being used. A LED battery meter displays remaining power level. Works with iPhone and any iPod with dock connector.
The Juice Pack Air is a rechargeable external battery concealed inside of a protective form-fitting case for the iPhone 4. It offers you the full protection of a hard-shell case while providing virtually twice the battery life of the iPhone alone. We love that is ultra-thin, light-weight, low-profile design. The Juice Pack Air is a rechargeable Smart Battery concealed inside of a low-profile, light-weight, soft-touch, 2-tone metallic case. Toggle between Charging and Standby with the flick of a switch. This is your best option if you want a seamless case/battery pack.