I have a Hangar 9 heavy duty starter on a 4S 3200 mAh LiPo, and this setup ROCKS! It'll turn over my 30cc gas engines with no effort at all.

I also bought a $5 project box at my local Radio Shack and mounted that to the bottom of the starter to house the 4S LiPo. I just packed a little foam wrap around the battery inside the project box, to protect the battery in case the starter was dropped.