My battery did the 10% remaining notice in the early evening. This never happened when on the regular release.
This is definitely going to be a daily issue, at least for Beta 1.
Consider this before installing it.
Just FYI -- when i installed 3.0 on the watch, battery life was awful. Went from 70 percent to 20 percent in an hour or two.
Then, at home, I unpaired the watch, wiped it, and re-paired it as a new watch with my phone. I also did not install any third-party apps on the phone, to see what would happen with only the stock (presumably optimized by apple) apps.
the difference is stunning. After charging up overnight, I did a 30-minute workout and it went from 100 percent to 97 at 9 am. It's now 2:30 pm and it's at 91 percent. Admittedly, i haven't used many of the apps, but have been getting a steady stream of email / message notifications.
so anyway -- mileage will vary, but if you are having battery problems, you might try what I did and see.
mike