I found the cause - the data sync. Each time you access the app on your phone, it syncs the data.

When you disable the wifi/data connection on your cell and access the app (while watch is paired), it tries to sync and fails. Problem is that it seems to be stuck in a loop until data connection is available and by then the battery depletes rapidly.



Solution - don't access the app while there is no connection in your phone to wifi/data.



Not sure if this is the only case when the watch syncs data - it might be syncing it automatically each day at a specific time - will post more info if i find out.



I also don't know if this bug is caused by the new firmware or not because i received the watch only last week and immediately updated to the new version based on the notification in the app.