During the iPhone announcement, Apple was quite keen to note that its iPhone 5C and the iPhone 5S will have an improved battery life and although it was not clear if that was a software or hardware tweak, according to a post over at Anandtech.com and some details from the FCC, the batteries inside the iPhone 5C and iPhone 5S are definitely beefier than the one in the iPhone 5.
While all batteries work at 3.8V, there is actually a difference in battery size. While Apple iPhone 5 was stuck with a 5.45Wh battery or 1,440mAh, the iPhone 5C has a slightly larger 5.73Wh or 1,507mAh. The iPhone 5S, with its speedy 64-bit A7 SoC, has even bigger one with 5.96Wh or 1,570mAh.
The best part of the story is that Apple managed to squeeze in a much better battery without compromising the size of the iPhone 5S, which managed to stay as thin as the iPhone 5. The iPhone 5C unfortunately did not share the same destiny and ended up a bit thicker, but this was probably the result of the polycarbonate redesign.