Motor not drawing expected amps

[pilgrim776]

I posted this on r/ebikes but I’m thinking this forum is probably more appropriate.

Hi everyone. I’m trying to help my son with a Razor MX650 build with 72V 3000W controller and motor. We have a YLAC-1 controller and what looks like a generic “BLDC 72V 3000W” motor. At full throttle, no load, a clamp meter shows about 1.3A DC off the positive side of the battery and about .35A on each of the three legs of the motor side of the controller.

There’s also a three speed wire connection which I can’t hear an audible change in the wheel spinning. It runs the same speed even when disconnected, but I’ve identified the two 5V legs which should be high/low speed and the common leg. When shorting each to the common, nothing changes in speed.

Any help or guidance is appreciated. Thanks!

 

[fechter]

The current measurement looks about right for no load. Under load it will be much higher.
Usually a 3 speed switch will affect the speed but I have one where it only affects the current limit.
Try a road test.

 

[pilgrim776]

Thanks for the guidance. I had the “reverse” wires connected and it must have made the controller power limit due to thinking the bike was moving in a reverse mode/direction, even though the motor was spinning “forward”. I learned how to use the “learn” or “study” wires to make the controller set the three phase in the right direction for the motor to spin with the reverse wire circuit open. This definitely opened up the power and now my three speed function is working. Thanks again for the help and direction.

 

[fechter]

Thanks for reporting the result. That thing should be fast.