I got my Fenix 6S last week and have noticed the battery only works for about 36 hours before it is completely drained. I have turned off pulse ox and HRM and it doesn't make a difference. The battery direction says 8 days, but it is completely wiped out in 36 hours (and that's without doing any workouts or using music!). So unless I'm completely exhausted losing time to sleep, this is a complete miss. Software is up to date.