On a whim, I decided to see what Gorilla Gadget has in the way of an extended battery for the S3. I had one for my Shift 4G and it was pretty good. Anyway, I got one; comes with matching back cover. Followed the instructions for prepping/conditioning it and I'm pleased to say it works great. For instance, I unplugged my charger yesterday morning, 10/18, at 9 a.m., and it's now 7:20 p.m. on 10/18. I am downloading the latest Facebook update and still have 3% left. This time has included heavy data use, numerous calls, downloads, etc. This is a 4500 mAh battery, and comes with the back to match your phone color (Marble White in my case); Blue, White, Red and Black. I paid $34.99 for mine. But I just checked the site and it's on sale right now for $19.99. So, if you need the extra battery life, I recommend you give it a try.
NOTE: Make sure you follow the instructions for conditioning the battery. Actually, you should follow their instructions for any new battery you use. But this is important to get the full advantage of the extended batteries.
NOTE: Make sure you follow the instructions for conditioning the battery. Actually, you should follow their instructions for any new battery you use. But this is important to get the full advantage of the extended batteries.