I never know what to think of "battery rundown" test where they loop a video or keep reloading webpages... maybe that's what you do with an IPad, but not a Surface Pro. So I did my own last night. I got 7 hours from turning on until the system turned off the screen and hibernate with 5-7% left. During this time I was working on a Word document, occasionally pulling up Excel and Stats (a high-end statistical program). I had Outlook open the entire time and checked email now and then. Did some web browsing here and there, had music playing in the background but not the whole time. Downloaded a system update. Never let the machine hibernate, though I got up to get food or use the bathroom. But the Surface always woke up with the capacitive Windows button or the keyboard, so I never had to use the power button to bring it back. My settings were the Power Saver profile with automatic screen dimming and just one change: CPU throttled at 50%. I never did a strict test like this with my SP1, but my sense was that it got 4-4.5 hours with similar configs. That's about a 50% improvement, a little less than I was sold on but nonetheless respectable. It's as good as I've ever had with a ThinkPad that doesn't have one of those grotesque extended batteries hanging out the back. So, I'm satisfied. I certainly am not crazy paranoid about charging every time I see a plug anymore.