I have tweaked the design a bit and settled on a relitively simple circuit for testing. My test circuit uses two DC motors one for generating power and one for creating motion to test the peak voltage output of the first motor. The test circuit spins a motor which has it's shaft tied to the second motors shaft the second motor outputs approx 2V which is used to charge a capacitor. When the motor stops spinning the capacitor holds its charge (excluding natural discharge) until a switch is pressed allowing the capacitor to discharge through the load.