Battery accessories wax and wane in value every time Apple releases a new device: when iPods became capable of playing music for 12, 24, and then 36 hours straight — sometimes more — the need for extra power declined, but the limited talk times of iPhones suddenly called out for new and better power options. Though the latest iPods, iPhones, and iPads all benefit from comparatively great run times, companies continue to offer new battery packs for those who may need them, and today we’re looking at three just-released hybrid battery and case options: Kensington’s PowerBack ($130), the first iPad-specific battery case, Kensington’s PowerGuard ($60), one of two iPhone 4-specific battery cases, and Mophie’s Juice Pack Air for iPhone 4 ($80), the device’s other battery case.
All three of these products have several things in common that should be mentioned up front. First, they’re all made from hard black plastic, finished primarily with soft touch rubber on the back and matte plastic on the inside. Each one provides access to the iPhone 4’s and iPad’s speakers and microphones without noticeable degradation in sound quality: Kensington and Mophie have both designed the cases with pass-through ports that iPhone 4 callers told us had little to no impact on speakerphone or handset mode audio, and iPad audio sounded completely the same, as well. Antenna reception did not appear to be impacted with the cases on, either. Finally, all three of the designs use Micro-USB connectors for recharging their built-in batteries, and come with USB cables that connect to your computer or a self-supplied wall charger for this purpose; none includes its own power adapter.
Dock Connector port access is blocked while the cases are connected.
Of the three batteries, PowerGuard is the least expensive, and also has the smallest rechargeable cell inside—1200mAh, which Kensington says will add four hours of talk time or five hours of video viewing to the iPhone 4. In practice, PowerGuard added 41% more power to a powered-on, 3G/Wi-Fi-connected iPhone 4 with the screen turned off, no calls coming in, and no audio playing, going from 20% to 61%. Notably, PowerGuard performed this charging process very rapidly, benefitting from a 1-Amp charging speed, faster than Juice Pack Air. Though the actual charge level would have been lower if the iPhone 4 was fully discharged, or higher if the device had been placed in Airplane Mode, a 41% gain in battery life under “charging but still on” conditions is good for the asking price, and enough for at least three hours of talk time.
PowerGuard’s only disadvantages are in its somewhat clunky body design, which is adequate rather than spectacular. Unlike Mophie, which has you slide the iPhone 4 into a shell with partial side protection and install a cap, Kensington uses a full front and side-covering glossy black snap-on frame that offers superior button protection but looks and feels a little cheaper. The battery pack on back gives the case an iPhone 3GS-like curve, and Kensington has designed the back with a green/red power switch, a single color-shifting light to indicate battery power levels, and a slot on the back that you can use in conjunction with an included plastic card or most ID/credit cards to prop the iPhone 4 up for video viewing—again, sort of cheap but also sort of practical. While PowerGuard isn’t the best looking battery case we’ve ever tested, it makes up for its lowbrow aesthetics with a little more protection and the lower price.
The iPad version, PowerBack, is a somewhat different story.
It does away with the snap-on front frame in favor of a slide-in sled-like design with small rubber pads to prevent iPad scratching, and has a fully rubber top portion that offers as much give as necessary when removing the iPad from the otherwise hard shell. Here, Kensington uses a four-light power indicator with a button on the bottom, recessing the Micro-USB connector in a groove on the case’s back, alongside a large silver video stand that pops out and rotates into positions ready for portrait, landscape, or keyboard use, working well to stabilize the iPad in each orientation. A large hole in the center of PowerBack exposes the Apple logo—a design element that we’ve never liked, though here, it may make iPad removal a little easier, and doesn’t carry quite the same scratch potential as when the same thing is done with iPhone and iPod cases.
PowerBack has what Kensington has alternately described as a 4200mAh or 4400mAh battery inside, promising “up to five extra hours of power”—half the iPad’s own built-in battery life. This large battery takes nearly as long to recharge itself as it does to refill the iPad, and in our testing with a Wi-Fi antenna on but 3G cellular and screen off brought the iPad’s battery up from 38% to 81%, a gain of 43% power, which will again be less if the iPad is fully discharged, and more if all of its wireless hardware is disabled. Kensington’s five-hour promise is very near the mark if the iPad is being left to charge in a smart way, rather than being actively used at the time.
As noted at the beginning of this review, the single biggest challenge facing PowerBack is the question of its actual value for the price: the strong out-of-box battery life offered by the iPad means that it doesn’t need battery help to the extent that older iPhones and iPods did, so a $130 cell that brings it 40-50% extra power with decent rather than great protection feels a little off to us. That said, the rear stand feature is nice, and some users will not mind paying the premium for a multi-function design that offers these features.
Last up is Mophie’s Juice Pack Air, the iPhone 4-specific sequel to a family of popular battery packs for past iPhone and iPod touch models. Juice Pack Air includes a 1500mAh battery, which the company promises will “virtually double” the device’s talk and video time—6 hours of extra 3G talk time or 9 hours of video, versus 7 and 10 for the iPhone 4’s integrated battery.