So I charged my SP3 up to full, let it nearly run out and then charged it again when I got it to calibrate it. But today it went from 100% to 19% just doing nothing. I checked task manager, nothing is eating up memory or CPU, I'm not running Chrome, in fact I was running nothing all day this has happened in standby. I looked at battery report and the battery for yesterday and says active 38 hours under battery life estimates... unlikely. The previous two actives from the days before say about 5 hours. Something weird is going on any ideas? Here's the life estimates from the report as you can see 10-11-2014 is a bit odd Edit: rattled thread as it appears it's not a battery issue, but an issue with the surface going into sleep. Many thanks.