Just replaced my Gear S3 battery (24$ + 10$ for tools). Excited to get 3+ days back. Links in comments, will report back with new battery life in a few days. : r/GearS3
Samsung Gear S2 classic (R735A) - Battery Life - AT&T
Samsung Galaxy Watch 4 review: Google smartwatch raises bar | Samsung | The Guardian
Samsung Gear S2 update brings improved battery life and security - Neowin