Speed Controller and Battery Question

[Antranik]

Hi there, can somebody please explain to me what is the purpose of a speed controller? Why are there so many options? Are speed controllers specifically meant for a certain voltage only? Do some increase the efficiency of the entire e-bike through smarter circuitry?

As for batteries, what does the voltage determine and what does the amperage determine? I see people have setups of... say... 24v with 10amp, or 24v with 20amp, what's the difference?

Thanks!

[WJChris]

More voltage means more speed, more amps (amp-hours) means further distance (more storage capacity) at the same voltage.