I recently updated my galaxy watch 2. Since the update my watch as been dieing very quickly. Last night I went to bed with 50% and woke to it being dead. Why is this happening and how to I fix it?
Check Background Apps and Stop Them.
In my case, the stock Gallery App was stuck running and sucking down all of the battery life, even AFTER several shut downs & reboots!
Open Galaxy Wearable App
Press the top summary where it shows the watch face, battery, etc.
Look at the Apps near the bottom under "Battery Usage Since Last Charge"
If you find a high-usage app, Press it, then Press "Force Stop" (bottom-right).
Update: Two months later it happened again. Two nights in a row the battery lost all power.
In this instance, I took two steps and it has resolved the problem.
Samsung Health was shown near the top of the list with 25% usage, although I had not used the Watch or Samsung Health any differently.
I repeated the steps in my prior post and Pressed "Force Stop" on it.
My Active 2 is an LTE version, although I do NOT have a Data Plan for it and have never activated it. So in this instance, I also did something different too.
In the Galaxy Wearable App, you can Add/Manage/Remove Mobile Plans. However, if you don't have a Mobile Plan, there doesn't appear to be a place to turn off the Mobile Connection. You can only click "Use Code" or "Skip". I had opened it then pressed "Skip", but there were no other options. So...
I did NOT do the following, but I'm noting this additional step here for future reference as other users/threads have indicated it helped: