PowerSkin (for iPhone 4 and 4S)

For a phone design that hasn't changed in two years, there's a seemingly infinite number of variations available for the Apple iPhone. From Xpal Power, the PowerSkin ($69.99 direct) for the iPhone 4/4S is slightly different from all of the other battery cases we've tested thus far in that it's made out of soft silicone rubber instead of hard plastic. That gives it a more protective feel than other cases, and its one-piece design adds to the sense of security. But it's little too heavy, and provides a little less power than many other cases out there.

Design and Features
Battery cases aren't known for their svelte design, but the PowerSkin  is the largest we've seen yet. At 5.1 by 2.5 by 0.8 inches (HWD) and 3.36 ounces, it adds a considerable amount of bulk to your iPhone. The  ($79.95, 4.5 stars), our current Editors' Choice, measures 4.90 by 2.40 by 0.67 inches and weighs 2.78 ounces by comparison. That large size makes the PowerSkin even less portable than most battery cases. It isn't comfortable to carry this around in your pocket—provided your pocket is large enough to fit it.

Unlike other cases, the Powerskin features a one-piece design made mostly of soft silicone rubber. That means you never have to worry about the top part of the case accidentally snapping off, and the thick rubber provides a more protective feeling that other battery cases. The back of the case is solid plastic, with a rubberized, soft touch coating. I don't like how the case covers up your Volume and Power buttons. There are rubber indicators you can press, but I prefer the tactile feel of the buttons themselves.

Now, I'm not willing to test it out with an actual phone inside, but I'd feel safer if my phone dropped while in the PowerSkin than, say, the  ($99, 4 stars). Still, if you drop your phone face down, none of these battery cases offer very much protection.

To use the PowerSkin, simply slide your phone in until it docks with the 30-pin Apple connector, then make sure the sides of it are tucked beneath the silicone. The bottom of the case contains a battery status button that triggers four blue status LEDs. This same button can also be used to power the case on or off when connected to your phone—simply hold it down until it stops (or starts) charging. There's a micro USB port on the bottom right hand side of the case, which allows you to connect the case to a computer for simultaneous charging and syncing with an included cable.

Performance and Conclusions
On its own, the iPhone 4S I tested lasted 9 hours and 22 minutes on a continuous 3G call. The PowerSkin uses a 2000 mAh battery that added 8 hours and 48 minutes. That nearly doubles your battery life, which is definitely long enough to get you through a full day of heavy phone usage. Still, this result isn't as long as some of the other battery results we've seen, like the PhoneSuit, which added 10 hours and 43 minutes of talk time.

If you're looking for a combination of security and battery life, the PowerSkin may be the right case for you. But if you're seeking something in a more manageable size, the PhoneSuit Elite  is easier to carry, provides nearly two additional hours of battery life, and costs just $10 more. Or if you want to save some money, the  (4 stars) will double your iPhone's battery life for just $49.95.

More Cases & Carrying Gear Reviews: