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 S3 Battery Life & Charger Options
Amazon.com: LCLEBM 520mAh Battery for Samsung Gear S3 Frontier (SM-R760),Galaxy Gear S3 Classic Replacement Battery for SM-R770,BR760,R765,EB-BR760ABE Gear S3 Battery with Professional DIY Repair Tools : Cell Phones & Accessories
Amazon.com: WUHAO Battery for Samsung Gear S3 Frontier SM-R760 SM-R760N SM-R765 SM-R765T,Gear S3 Classic SM-R775T Replacement Battery, EB-BR760ABE for GH43-04699A Battery with DIY Repair Tools : Cell Phones & Accessories
How to use a Samsung Gear S3 smartwatch with an iPhone—and why you might want to | Macworld