It is estimated that Microsoft will provide Windows tablet 31.4Wh RT rating for them and for Windows 43Wh 8 Pro Surface. While the new iPad has a battery with a claimed Apple 42.5Wh hold up to 10 hours to surf the internet, watching videos and listening to music. This means Windows RT Surface has a battery capacity of approximately 25% of new iPad battery, which will last only 7.5jam. But of course many other factors that influence the level of resistance of the battery in a device, the lack of information about Windows RT Surface makes this prediction difficult. When compared with iPad 2 which has a battery with 25Wh, it is known that the battery on the iPad 2 was 25% smaller than the battery of the Windows RT Surface. If you follow Apple's claims, iPad 2 itself can last up to 10jam (without Retina Display) which means that Windows will be able to survive RT Surface 12.5jam.
Of course we still have to wait for the official disclosure of the Microsoft Windows tablet RT on them this