What is your typical battery usage of the Garmin Connect app on the iPhone? During the last 10 days the mentioned app has used approximately 3 % of my battery per day.
Will depend on how much you look at the app not just background usage and how much your watch syncs , also what other apps you use. im on 17% for the last 10 days and 10 % today so far but I have been recording all day activities since Saturday.