I've had the same problem, I have the highest specced Pro 8 and battery life was an important decider, but it's horrible. It's not even 11:00, I've been working on it for 2 hours doing nothing but chat, and write tekst in a tekst program ... and we went from full to 66%. All drivers are updated, all updates are installed. It's getting worse compared to last month.
Microsoft, please fix your insanely expensive product.