You may have a look at this thread. It seems that it will be a tight fit and might stress the springs a little too much on the long term. Personally I don’t have the s3 but the s2+ and you can put a 3,400 Pan but doesn’t feel good.
However these lights are pretty safe with a reliable unprotected battery, so if you have a decent charger I would go for an unprotected (which is what I do on the s2+)
EDIT: Just saw at Simon’s that he says: “Now protected and unprotected 18650 lithium battery all can be used in this flashlight”. However that doesn’t mean that it will be a comfortable fit and doesn’t contradict the above