The Samsung Gear S3 has received an important update. Coming in at only 21 MB, itis claimed to fix battery problems, with the only change mentioned being an improved battery usage time. If you are also experiencing battery issues, the recent update should fix that.
The latest update is currently rolling out in Canada, but the Korean giant has confirmed to 9to5Google that they are rolling out the update for the rest of the Gear S3 models worldwide, including the Frontier and Classic versions.
According to GSMArena, The battery drain problem is probably because of the Tizen OS 3.0 update which rolled out a couple of weeks ago. To check if the update is available, check the Gear app on your phone.