48V1500W vs 72V1500W

I saw an ebike hub motor kit for sale where I could choose between a 48V1500W or a 72V1500W Hub motor. I was not able to find the information so I'm asking here.
From my actual understanding:

A 48V hub motor can be run with 72V battery, but does a 72V hub motor necessarily has to be ran with a 72V battery?

Does the controller voltage rating has anything to do with the hub motor voltage rating? For instance, would a 48V rated controller work with a 72V rated hub motor?

And, I thought the controller amperage had to be higher than the battery, but I saw another source saying the opposite. What is the right answer?

a "72v" motor will run fine on 48v, but will run slower than it would on 72v. Within reason, you can use whatever voltage you want on any motor to get the speed you want.

Controller voltage rating should match your battery voltage. Some controllers can work with a range of voltages.

Controller should not be able to draw more power than your battery can safely deliver. A big controller on a low performance battery will kill the battery fast.

Basically your controller decides how much power you will draw from battery and deliver to motor. If your components are not well matched, you run the risk of frying the weak link in your chain.

It's better to look at it from the how fast do you want it to spin aspect, but it's kind of guess work without good info from the seller. Let's say you want to go street legal speed. If the seller just uses the same motor, but a different controller, then on 72v you will have to be on partial throttle all the time to be legal, or maybe you need it for a small diameter wheel that needs more rpm.

But maybe the 72v one has been adjusted by changing the number of turns so it still runs at a normal street rpm.

That's what's hard to know without good seller info...

FYI, on my setup, the so called 48v motor I got second hand was too slow, so putting 72v thru it to get more rpm...

maanebedotten said:

a "72v" motor will run fine on 48v, but will run slower than it would on 72v. Within reason, you can use whatever voltage you want on any motor to get the speed you want.

Controller voltage rating should match your battery voltage. Some controllers can work with a range of voltages.

Controller should not be able to draw more power than your battery can safely deliver. A big controller on a low performance battery will kill the battery fast.

Basically your controller decides how much power you will draw from battery and deliver to motor. If your components are not well matched, you run the risk of frying the weak link in your chain.

Click to expand...

How would someone go about changing the settings of a controller so that is outputs a legal amount of power?