“When you put all that weight in the top of the product, it’s like 1.57 pounds on the top, you have to balance that out with base. That’s the key. Every single trade-off in the product, how much battery you put in, how much battery you put down bottom, how do we hold to the 12-hour target that we set?” said Panay. In the end, the battery is split, though not evenly, between the base and top. The top gets four hours of battery life, and the bottom gets eight.
So, you get only 4 hours of battery life with the top. The good thing here is that you can charge the top separately without the need for the keyboard base. So, Surface Book top can act as a powerful tablet and can function without the need of keyboard base.