EB BR760ABE 380mAh Original Battery For Samsung Gear S3 Frontier Gear S3 Classic SM R760 SM R770 SM R765 with Professional Tool|Mobile Phone Batteries| - AliExpress
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