I have a series 7 watch----when OS10 came out I started losing battery, I would be at 50% by the end of the day. Now, I'm between 11%-21% by the end of the day---it's been happening since the beginning of the year and getting worse each time. I have reset, wiped as new, etc---works good for a few days then back to losing 80% in 14 hours. Long gone are the days when I was 76% at the end of the day with my watch. I wish they would fix this as just about everyone I know with an apple watch says the same thing regardless of their OS.