Review: Eight iPhone 4 Battery Cases

Compared to some of its competitors, the iPhone 4’s battery life is surprisingly good. But few of us would complain about squeezing a few more hours between recharges. And, of course, many iPhone 4s have been in use for over a year now, so their battery life is gradually getting shorter. In my quest to extend my phone's daily life, I tested eight iPhone 4 cases that include built-in batteries for powering the phone.