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
Amazon.com: for Samsung Gear S3 Classic,S3 Classic SM-R770NZSAXAR Replacement Battery, for EB-BR760ABE/GH43-04699A Battery with DIY Repair Tools : Cell Phones & Accessories
Amazon.com: PAISUE [430mAh] Battery for Samsung Gear S3 Frontier (2023 New Version) Replacement Battery for Gear S3 Classic SM-R770, R760, R765, EB-BR760ABE, GH43-04699A with DIY Repair Tools : Cell Phones & Accessories
Samsung Original Replacement Battery Eb-br760abe For Samsung Gear S3 Frontier / Classic Smart Watch Sm-r760 Sm-r770 Sm-r765 - Mobile Phone Batteries - AliExpress