If you're anything like me, you probably use your iPhone 4S constantly for everything from checking email and text messages to chasing a new high score in Temple Run. But if your iPhone is anything like mine, you're probably scrambling to find an outlet at the end of the day. The folks at Mophie have taken the Editors' Choice winning Juice Pack Air ($79, 4 stars) iPhone case and increased the battery size by thirty percent for the new Juice Pack Plus ($99 list). It's still big and bulky, but this beefed-up battery case helps propel the Juice Pack Plus past its predecessor, and is well worth the $20 premium.

The Juice Pack Plus is very similar to the Juice Pack Air, so I'll give you a quick rundown of the subtle differences. First and foremost, the battery has been bumped up from 1500mAh in the Air to 2000mAh in the Plus. Mophie was able to keep the dimensions nearly identical at 5.10 by 2.57 by 0.71 inches and 2.5 ounces, but that still almost doubles the thickness of the iPhone and adds some significant heft.

The design for both cases is pretty much identical. The major difference here is the addition of physical Volume buttons, which are easier to press than the simple cutouts on the Air. Both Juice Pack models use a button to activate the battery status LEDs on the bottom of the case. They also have the same power toggle switch, allowing you to control when the juice is flowing, along with a microUSB port (a cable is included) for simultaneous charging and syncing. The Plus is also easier to take apart, with a smoother and less-resistant sliding mechanism. This isn't necessarily a good thing, though; I prefer a more secure snap, like the Kensington BungeeAir Power's ($99, 4 stars) back and faceplate pieces which have a physical lock switch. I tend to fidget with things like remote control battery covers and found myself doing the same with the Juice Pack Air since it slides apart so easily. You get a wide variety of color choices including blue, pink, yellow, purple, red with black accents, all black, or like our test case, glossy white with a rubbery gray band around the case.

Performance and Conclusions
In our tests, the original Juice Pack Air was able to effectively double the battery life of the iPhone 4. To test the Juice Pack Plus I used an iPhone 4S on Verizon's network to make a continuous call over 3G. By itself, the iPhone 4S lasted 9 hours, 22 minutes. The Juice Pack Plus added an impressive 10 hours, 43 minutes of 3G talk time. While it bests its predecessor, if you already have the Air, it's hard to justify dropping another hundred bucks for an extra 90 minutes of battery life with no additional features. But if you're getting your first Mophie case, I suggest dropping the extra $20 for the Plus.

The Mophie Juice Pack Plus will effectively double your iPhone's life between charges—but it will also double the thickness of your phone. The pieces come apart a little too easily for my taste, but the mere girth of this case will assuredly protect your delicate iPhone from harm. Alternatively, the BungeeAir Power will add some nifty security features, but offers a more modest bump in battery life. Lastly, if you don't want as thick a case, the ExoGear Exolife ($89.99, 4 stars) is the thinnest battery case we've tested, and still offers a good amount of extra juice.

Source: www.pcmag.com