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Old 09-24-2012, 11:14 AM   #72 (permalink)
rmay635703
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Quote:
Originally Posted by SeniorSell View Post
Ryan, I have a 2007 miles ZX40 with the larger 9hp 72V DC version motor. Curtis controller. We know that this motor will take 6,000 rpm for some time, not constant. That = about 42-45mph stuck in second gear. Bone stock at 25mph indicated is at or about 3,300 rpm. I read that field weakening is the quickest way to attain more speed but couldn't I also pull the controller and send it to Curtis and have them raise the RPM limit to say 5,500 rpm?

Dave Upton
Controller is dumb and ignorant of what your motor is doing. The limiting factor is you motor will only accept so much amperage at a given RPM, BACK EMF prevents current flow, reducing field strength reduces EMF and increase current flow which reduces power but increases max RPM of the motor.

From what I have been told 6250rpm is the max on both the small and big motor (my mistake), which is fairly impressive, so don't go over 46mph with stock gearing.

Motors are moderately robust but can be overheated if you abuse them for long periods.
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