Apple Watch not charging fully overnight
Why isn't my Apple Watch charging fully overnight ?
[Re-Titled by Moderator]
Apple Watch Series 9, watchOS 10
Question marked as
Any chance you have Optimized charging and/or Charging Limit enabled in the settings for battery?
You can disable this feature and charge your watch to 100% each time you put it on the charger.
Have a look at the related article, in which it is also being explained, why Apple introduced this option:
About Optimized Battery Charging on your Apple Watch - Apple Support