You could look into this. I've not tried it but it should work provided you don't go nuts with it. There are a lot of people that are running 36v and it you setthe max as in the video that's about what he is running. And for 100 bucks it cheap. Of course you would need a second battey to get the voltage needed.

Bob

http://www.youtube.com/watch?v=ehKSU..._order&list=UL

http://www.youtube.com/watch?v=WjTyB..._order&list=UL