Here’s some progress for those of us putting together our new iPhones one piece at a time. 9to5Mac has published photos that appear to be a leaked battery for the anticipated but unannounced next iPhone. (Leaked as in “revealed before the phone’s release,” not “dripping with battery acid.”) When we compared the images of the leaked battery to the current iPhone 4S OEM batteries from iFixit, we found that the battery appears to be longer but has similar markings.

iPhone 4S battery (from iFixit) beside leaked next gen iPhone battery.

Though the battery seems to be longer than the one you’ll find in an iPhone 4S, the spec bump is fairly modest. It’s capacity is 1440mAh, up from 1430 mAh, and it uses that power to pump out 3.8 volts and 5.45 wHr (the iPhone 4S’s battery is rated for 3.7 volts at 5.3 wHr. The battery was apparently produced in June, which puts in in track with rumors for the next iPhone’s manufacturing.

Will the slightly higher capacity battery provide adequate power to the next iPhone? Between the larger screen real estate, the 4G LTE antenna that will almost certainly be providing wireless connectivity, and the inevitable spec-bumps over the iPhone 4S, Apple will have a challenge in keeping the battery life acceptable. LTE technology has a reputation for draining more power than 3G, and larger screens require more LEDs for illumination.

Then again, as the most profitable technology company in the United States, Apple has a lot of staff and buying power. If any company can find a way to squeeze efficiency out of faster components… well, Apple could buy the technology from them at any rate.

The markings on the front of the battery also resemble the current design.

The iPhone 4S is generally estimated to be good for about 6 hours of continuous 3G browsing. What would be an acceptable battery life for Apple’s next iPhone? Share your thoughts in the comments section below.