I use the Tenergy RCR123a 3.0v 750mah batteries. Have been using them since I bought my SB last summer. I get a good 6 hours from them and am a heavy vaper.
My SB is my FAVORITE mod and you will not be sorry for buying one!! This is a vapin machine for sure! I love it with the 510 atty and a drip tip, but it also works great with a 801 too.