I charged up my SP3 this AM to 100%. Closed lid, headed out at 8:30am. 6.5 hours later, I started my SP3 back up and battery was down to 66%!!!! Prior to my Windows 10 install, the worst I have dropped was between 5-6%. Any suggestions or ideas? The machine was sleeping and I did have Cortana activated so I'm wondering if this could be the reason? Part of the issue is I have no way, that I know of anyway, to tell what was the culprit... my iPhone will tell me what is using the most battery. My Samsung Note would do the same. But not this?