Ivyskin BatteryPack for Quattro 4 SmartCase
Though it falls into the "accessory to an accessory" category, Ivyskin's BatteryPack for Quattro 4 SmartCase ($45) finishes what the Quattro 4 started back in September, serving as a slide-on 1700mAh battery for the iPhone 4 that integrates with the earlier $45 plastic, glass, and rubber case. A five-LED power indicator, pass-throughs for speaker and microphone features, and mini USB charging port are on the BatteryPack's back and bottom; holding down the power indicator button turns the battery on and off. Expect nearly a full doubling of the iPhone 4's battery capacity if you give it a whirl; our review sample oddly exhibited some TDMA-style noise at one point in early testing, and the iPhone began searching for AT&T service. Ivyskin now sells both the BatteryPack and Quattro 4 together as the iPhone 4 SmartCase for $80, or the BatteryPack in four colors for the $45 asking price mentioned above; each BatteryPack includes a USB charging cable.