Early reviews of the Surface Pro, even the favorable ones, griped about the device's so-so battery life, which ranged from 2.5 to 4.5 hours, depending on usage. Not terrible, perhaps, but also not on par with the 6-hour (or longer) lifespan of similarly priced Ultrabooks like the Acer Iconia W700.
A solution may be coming soon, however, according to some industry watchers. In a Reddit Q&A session in February, Panos Panay, a Microsoft corporate vice president working on Surface, said the company went with a smaller battery to keep the Surface Pro thin and light (under 2 pounds). When asked if Redmond had plans to offer an extended battery, or perhaps even a keyboard cover with a built-in battery, Panay replied: "That would require extending the design of the accessory spine to include some way to transfer higher current between the peripheral and the main battery. Which we did." Intel's new Haswell chip (more on this later) will help boost battery life too.