Thanks for the replys. I downloaded the drive calculator but there are too many variable that I wouldn't know how to convert to a surface application so I don't think that will work much for what I am trying to figure out. also I did check out the http://www.scriptasylum.com link and they have some good info there. not just the power output calculator. I will have to bookmark them! but it sounds like I will just have to get a few different batteries and do my own testing. If anybody knows of a calculator that is ment specifically for surfacevehicke or know how I can convert some of the variables to a surface application that would be awesome! Thanks