sorry for the rather lengthy post....
here’s my experience regarding the battery life of my AW4 44mm SS LTE:
before watchOS 6, my watch sat around 45% by the end of a regular day of usage or aprox. 30% if an hour of workout was done also.
After the upgrade to watchOS 6 my battery life went crazy. I’d take the watch of the charger at 6:30AM and the watch would shut off with the battery completely drained by 2:30pm in the best case. Worst case I experienced was 6:30 to noon witch just little usage of the watch.
I tried all the hints one can find on the web. From restarting watch and phone, recoupling the watch, factory reset and set up as new, disabling LTE, background activities, removing the eSIM altogether. Nothing gave any improvement on the matter.
I opened a case with Apple support back in December. Had to install some kind of profile on the watch to let Apple collect debug data of the watch. Haven’t got any reaction from them since other than they’re still evaluating my data.
last week I realized that my 2009 MacBook Pro was not syncing several iCloud services anymore, like safari bookmarks, notes and reminders. That’s due to the fact that the MacBooks latest officially supported MacOS is 10.11 El Capitan. Apple won’t let me upgrade to a later OS. But that is required for all the syncing to happen.
After doing some research I found a software called “Catalina Patcher”
This software gets the latest MacOS running on officially unsupported machines.
After finishing my upgrade and logging into my iCloud on the MacBook, my iOS devices (iPad and iPhone) required me to reenter my iCloud credentials and then showed a screen which said something like “iCloud settings are being updated...”
I let it finish which took quite a while, then went to bed leaving my dead watch on the charger.
The next day I put my watch on at 7 in the morning. After a full day of usage without working out I had 38% of charge left at 11pm.
An hour of workout included the next day gave me 12% remaining battery after wearing it for 17hours.
That was last Friday and I haven’t had the watch die a single day since. Today I took it off the charger at 0645AM and I’m at 73% at 1pm.
I’m still holding my breath if this situation will be lasting but my confidence is growing each day.
so for me it seems that my battery drain problem was created by some sort of iCloud server sync setting being outside the normal range.