I have the exact same issue. I actually had my watch changed thinking it was an internal battery issue only to learn it was mainly the beta software. I have back ground app refresh OFF; all non-essential app are deleted. I have experimented with many issues to isolate the problem. On my AW6, first, I killed using my watch as a remote and it helped. Next, I turned off the O2 sensors ability to check my levels randomly throughout the day - that dramatically helped. My watch on some days will be at 60% when I go to bed. Many days, it will go from 100% to 0 in just 3 to 4 hours. There is a bug in the software but I am convinced the battery is not big enough to operate all the features packed into the watch. Shameful.