Best answer: Lenovo ThinkPad X1 Extreme has a stated battery life of around 15 hours, which depends entirely down to the configuration you select at purchase, as well as how you use the notebook. Kitting the notebook out with all the best available options can bring that figure down to as little as six hours. Dell's XPS 15 may be a better option with a larger battery pack.
Full story from the WindowsCentral blog...