Extended battery works well for me and I leave the stock battery in the glove compartment of my car. Better there than to leave it home.
Amazon.com: Hyperion Samsung Galaxy S3 4200mAh Extended Battery + Pebble Blue Back Cover (Compatible with Samsung Galaxy S3 GT-i9300, AT&T Samsung Galaxy S3 Samsung i747, Verizon Samsung Galaxy S3 Samsung i535, T-mobile Samsung Galaxy S3 Samsung
http://www.amazon.com/dp/B008MMZUZS...ag=hawk-future-20&ascsubtag=UUacUvbUpU2268914
Amazon.com: Hyperion Samsung Galaxy S3 4200mAh Extended Battery + Pebble Blue Back Cover (Compatible with Samsung Galaxy S3 GT-i9300, AT&T Samsung Galaxy S3 Samsung i747, Verizon Samsung Galaxy S3 Samsung i535, T-mobile Samsung Galaxy S3 Samsung
http://www.amazon.com/dp/B008MMZUZS...ag=hawk-future-20&ascsubtag=UUacUvbUpU2268914