i was thinking 48 or 72 volts. that means up to 300 amp speed controller, like these:
Wow, thanks for all the replies! You are probably right about the 300 amps, I just want to be safe. I want some decent range so at least 100 amp hour deep cycle lead acid batteries. What about a diagram?? I'll try and make up one that I think would work. Thanks again!
Maybe something like a IGBT. They're made for things with high voltage/current
@PeterH, sorry forgot to mention sealed lead acid batteries. I have access to welding and metal working equipment so i was intending on modifying the frame so they would fit and be protected.