When Apple announced its iPhone 5C this week, it made a point to validate the new plastic body design by claiming improved antenna reception--due to the use of a steel frame--and increased battery capacity. The iPhone 5C is larger than the iPhone 5, so it makes sense that Apple used that additional space to fit a better battery. Now, FCC filings have revealed that the iPhone 5S also has a new battery, this one even bigger than what's in the 5C. Anandtech's Brian Klug uncovered the report, indicating that the iPhone 5S's battery is rated at 1570mAh, or 10% more capacity than the iPhone 5's 1440mAh battery, even though both phones are the same size. The 5C has a 1507mAh battery. Curious that Apple didn't tout the iPhone 5S's larger capacity battery in its announcement, indicating to me that they really wanted to put more attention on the 5C.