Can I convert to less AC volts to get more amps?
Energy must be conserved. You cannot get out more than you put in. Assuming you are having a constant power draw, the power in is going to equal the power out. Therefore,

[Amps in] x [Volts in] = [Amps out] x [Volts out]

So, if you are stepping up 12V 100A to 100V, you are going to get 12A (less with losses) out.