Depends on how you run and how you gear it. I would take a guess of about 40 min or better. That is just a guess so please don't hold me to it. I was getting 25 -30 min on a 9xl and 3700 nimhs 18cells.
http://66.241.195.91/lithium/lithium.asp?path1=lithium
Mike said something about getting these in. I don't know if he did.