Mophie has released Juice Pack Plus ($120) for iPhone 5, the company’s third battery case for iPhone 5, following Juice Pack Helium and Air. While falling behind top rivals in capacity, Juice Pack Plus has become the family’s most powerful battery case, featuring a 2100mAh battery that claims to offer 120 percent of extra battery life. According to Mophie, Plus will deliver up to 10 additional hours of 3G talk time, up to 12 additional…