Testing consisted of full battery discharge while performing each of the following tasks: video playback, audio playback, and Internet browsing using Wi-Fi. Video content was a repeated 2-hour 23-minute movie purchased from the iTunes Store. Audio content was a playlist of 358 unique songs, consisting of a combination of songs imported from CDs using iTunes and songs purchased from the iTunes Store.
Internet over Wi-Fi tests were conducted using a closed network and dedicated web and mail servers, browsing snapshot versions of 20 popular web pages, and receiving mail once an hour. All settings were default except: Wi-Fi was associated with a network; the Wi-Fi feature Ask to Join Networks and Auto-Brightness were turned off. Battery life depends on device settings, usage, and many other factors. Battery tests are conducted using specific iPad units; actual results may vary.
Steve says that iPad will offer ~140 hours of continuous music playback provided the screen display is turned “off” while the battery will last for ~10 hours if you use it for reading books. Steve says that the iPad chip [A4] doesn’t use much power but the screen does. I guess the numbers would be similar for web surfing as well.
http://video.allthingsd.com/video/w...ple-ipad/B3007E41-259C-4357-961E-7DC2C453CD30