Dexim recently debuted the Super-Juice Power Case for providing extra battery juice to the iPhone 4 on-the-go, and here's the hands-on review.
Ultimately, this accessory is a case, so you can't expect too much of a set-up process. All you get included in the box is the power case, a microUSB cable (with a handy velcro strap to keep things together and untangled), and the user manual. An optional accessory you might want is an AC adapter for USB cords, which I'll get to later.
To insert your iPhone 4 in the case, do not try to squeeze it in automatically. You might hurt your phone or yourself. Or both. Rather, you can unhook the top and then gently slide your iPhone 4 onto the Apple 30-pin connector.
While the Super-Juice Power Case won't be fully juiced when right out of the box, there should be a small amount of charge in it. Thus, the iPhone charging screen should immediately pop up. From here, you have two charging options. Plug in the other end of the USB cable to your computer, or into the wall if you have an AC adapter with USB ports.
The built-in 2000mA Lithium Polymer battery is supposed to extend your iPhone 4's battery life by the following times:
Talk Time: Up to 6 extra hours
Video/Gaming: Up to 10 extra hours
Audio playback: Up to 40 extra hours
Normally, the iPhone 4 can squeeze out a maximum of 840 minutes (14 hours) of battery life. But that's if you're only talking on 2G service. So in reality, you'll get maybe seven to eight hours out of one full charge. I typically charge my smartphone every other day. If not, the battery will deplete itself since the iPhone 4 is known to constantly search for a signal when it can't find one, running the battery out with the user not even doing anything.
While the Super-Juice Power Case powers up the iPhone 4 slower than it would being plugged into a computer or a wall socket, it does get the job done. I didn't charge my iPhone through a plug for about four days, and I could have gone longer. (But I hate taking risks, especially when about to travel, as I was then.) For reference, I mostly just listen to music on my iPod, but often I also use apps that require an Internet connection. I rarely talk on the phone.
Speaking of travel, an additional useful feature is the solid metal kickstand around the back, useful for propping up the iPhone in landscape position when streaming Netflix and YouTube or watching other movies on your smartphone. Note that this isn't a case that you would normally want to keep your iPhone in all the time. It's quite bulky, and it's never a good idea to keep your gadgets constantly charging.
The Super-Juice Power Case for the iPhone 4 is available now with an MSRP of $79.90.