Plagued by shipping delays due to Apple's certification process, mStation's mophie iPhone Juice Pack is the first iPhone battery extender, letting you surf, talk, listen, and watch twice as long between charges. It also (mostly) manages to maintain the iPhone's slim profile and can help prevent your favorite gadget from slipping out of your hand.
The price of adding an external battery to the 4.8-ounce iPhone is that it adds 62.5 percent (3 ounces) extra weight, which dragged down our pocket slightly. Fortunately, the modestly increased thickness (a total of 0.75 inches) didn't cause too much pocket bulge, though the battery adds a little over half an inch of height.
The Juice Pack protects the iPhone's back, which is far more susceptible to scratches and dents than the glass front, and the green inner lining doesn't scuff despite a tight fit. A black nonslip coating and gray rubber strips on either side provide an excellent grip. On the back are four blue LED charge indicators; press the small button next to them to see the battery's remaining juice.
MStation smartly designed the case so it doesn't block the iPhone's camera lens, buttons, or speakers, and it doesn't interfere with cellular or Wi-Fi performance despite obscuring the phone's antenna cover. Another smart move: The iPhone always uses the Juice Pack's battery first, so the iPhone stays fully charged. The company claims the juice pack offers up to 24 hours of audio playback, up to 8 hours of talk time, up to 7 hours of video viewing, and up to 6 hours of Web browsing.
When we tested it, the Juice Pack performed as claimed, doubling the life of our iPhone's battery to about 4 days. With the screen's brightness set low, the EQ off, and e-mail set to check manually, each day we talked for roughly 1.5 hours on the phone, sent about 12 text messages, listened to music for about 3 hours, and surfed the Web and checked e-mail for another 3 hours. We also used other apps such as Notes, Calendar, Photos (taking about two shots per day), and Calculator for about an hour total.
Our only gripe is that, although the dock connector on the Juice Pack's bottom lets you charge both devices simultaneously or separately, you can't sync the iPhone while it's in the battery jacket.
Given how addictive the iPhone is as an Internet device--which drains the battery most--the Juice Pack is an extremely welcome addition to the iPhone's accessory arsenal. However, if you're planning to buy a new iPhone, wait until mStation releases an updated Juice Pack in mid-to-late August, according to the company. This device is definitely worth the $100 premium if you spend extended periods of time away from an outlet.