In the midst of a flurry of announcements from Apple, I’ve been particularly interested in the little 13″ Macbook Pro. I currently use the Aluminum Unibody 13″ MacBook and I was curious about Apple’s “7 hour” battery claim for the new model. The first thing I did once the Apple Online Store came back online was to check the battery size of the new model versus the old one, and ensure they kept the same size and weight.

The conclusion is that the new 13″ MBP is the exact same size and weight, but that its battery stores about 29% more energy than the Aluminum Unibody model it replaces (58 watts in the new non-removable battery, versus 45 watts in the old model’s removable battery). This means that the real world numbers for the 13″ MBP are going to be excellent — 7 hours is probably an unrealistic number, but 5 hours of real-world use is very likely.

The thing that makes me wonder is, how do they do it? Is it possible that 30% of the battery’s weight and volume is in its removable enclosure? Or has Apple perhaps learned some neat chemical tricks that allow them to pack a bit more energy into a given amount of space? Is that also how they managed to upgrade the new iPhone 3GS’s battery life the way they did?