I assume that since all 3 batteries (MBp 13", 15", 17") are same tech. And I assume cubic inches of battery are proportional to watts. And larger screen size allows a similar enlargement of how many square inches of battery are in the lower case. Now unless the 13" MBp's battery is somehow thicker... (nah, how could that be?) it seems that increasing a screen from 13 to 15 to 17" should, roughly speaking, allow the battery power to catch up. So, intuitively, the new MBp's 15" & 17" with the new chip associated with progress in battery life, should pull ahead of the 13" MBp. But the 13" has the stated ten hour life, and the bigger ones, are rated at less. I must be missing something. How does a less efficient core-duo chip win the battery life competition?