The battery increases from 1430mAh to 1440mAh. That's a relatively tiny upgrade, but in line with the bump from the iPhone 4 to 4S (1420 to 1430). But here's the thing: The reason that we haven't seen LTE to this point is Apple's dedication to great battery life. LTE sucks the life out of phones way too quickly for the batteries on previous iPhones to last for a whole day. The hope had been that a larger, thinner, and more efficient screen, and therefore a bigger body for more battery.
For comparison, the Droid Razr Maxx has a 3300mAh battery. You can do that maths. Most other phones are coming in at 1800+.
Now, maybe the phone is running super incredibly efficiently, and the battery won't matter at all. Maybe this rumor's totally wrong and we're wringing our hands for nothing. But if this is the new iPhone battery, and if the new iPhone has LTE, and if it abides by the same battery life curves as other LTE phones, then, well, this sucks. [9to5mac]