Mophie Juice Pack Air for iPhone 4
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.
Mophie’s Juice Pack Air is 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. While the battery wasn’t as speedy at refueling as Kensington’s PowerGuard due to a 0.5-Amp charge speed, and didn’t meet Mophie’s claim under what we consider to be “normal” use conditions—powered on with 3G/Wi-Fi on, screen off while charging—it added 70% battery life under these conditions, or 40% battery life for a fully discharged iPhone 4; once more, antennas off will lead to more power, screen and other features being used will lead to less. Mophie’s “virtually double” claim will be met only if you disable most of the iPhone 4’s features during charging.
Of all of these designs, however, we liked Juice Pack Air’s casing the most. Though it has the tapered, iPhone 3GS-like rear bulge of the Kensington case, it’s noticeably several millimeters thinner. It also uses a classy side ring of matte silver plastic to mimic the look of the iPhone 4’s central antenna, and does a really nice job of integrating a small colored power switch, four bright power indicators, and a Micro-USB port into the silver ring rather than all over the case’s back. We preferred the way the iPhone 4 satisfyingly slid into this shell and received a cap at the top only, rather than using a full front snap-on bezel like the Kensington solution, though it was offset by weaker button protection and no video stand option, features that Kensington built into PowerGuard.
Overall, we’d give the edge to Mophie’s Juice Pack Air for iPhone 4 over both of the other battery cases because it does the best job of balancing both extra power and a really nice case design that looks and feels better while providing more energy to the device inside. That said, it comes at a higher price, and has similar limitations—none of these designs has screen protection, and button coverage isn’t what it could be on any of them, either. All three of these cases could stand to be at least a little better, but they’re all good enough to merit ratings in our B category: Juice Pack Air at the high-end with a B+, PowerGuard in the middle with a B, and PowerBack for iPad a limited recommendation and B-.
Updated June 27, 2011: Roughly eight months after the debut of Juice Pack Air, Mophie unexpectedly released an upgraded “Apple Edition” of the Juice Pack Air, which for reasons yet to be explained was redesigned at Apple’s request to provide a more open top and a slide-on bottom. It’s possible that this new version reduces sliding of (and subsequent scratching by) the back plastic against the iPhone 4’s rear glass. Four pictures of the Apple Edition, which is now stocked in stores, are above.