Hello TheCainMan,
Welcome to the HP Forums, I hope you enjoy your experience! To help you get the most out of the HP Forums I would like to direct your attention to the HP Forums Guide First Time Here? Learn How to Post and More.
I understand you are looking for some advise on how to extend your battery life on your HP Spectre XT Touchsmart Ultrabook. I am providing you with a link to an HP Support document: Improving Battery Performance (Windows 8, 7, Vista). If you review and follow the document you should be able to extend your battery life. As for how much I cannot say as a lot of it depends on how you use and that is different for every user.
I hope I have answered your question to your satisfaction. Thank you for posting on the HP Forums. Have a great day!