i tested the battery pretty extensively and the best i could ever get with dim screen and power saver settings was just over three and a half hours. the battery is going to be difficult to replace on this unit as well. This was a dealbreaker for me and the vivobook went back.
Hi. I never tried running out the battery. So far I have used for browsing (6-7 tabs at once, no video), wifi connection, screen brightness 100, and with around 66% battery left I could read estimated 2hour usage. Have you used touchscreen laptop before ? I previously used HP Touchsmart tm2 with windows7 pro. I find vivobook has much better touchscreen and windows8 is definitely for touchscreen device. But I do love touchsmart's screen because I can rotate and fold it so can turn into full tablet's form