Can a low wattage controller run a bigger wattage motor

[Pegasus195]

I'm wondering if I can get a 1500w motor to run using a 500w motor controller[we're talking about the same voltages for the motor & controller]. I don't mind the motor not running the full power like just running about 15-20mph(around 300w) is enough at the moment, I just wanted to know if I can run my motor(1500w) with my old controller(500w), cause I haven't decide which 1500w motor should I be buying for my next project controller yet. I did tried running my 360w 48v motor with a 48v 7A controller, and it decided not to work. So I'm afraid that i need to buy a 2000w contoller instead of 1500w. Thanks

 

[Punx0r]

Yes. The controller's current-limiting will simply limit power to ~500W

 

[DAND214]

Yes. The controller's current-limiting will simply limit power to ~500W

I agree that the controller will work. The other one should of too. Not all controller/motor wiring is the same. Colors do not always match and you need to switch the phase and or the hall wires to get them to work.

Dan

 

[miuan]

The only problem could be if motor is geared too fast at a given voltage and controller is forced into PWM all the time.
Say if your no load RPM is 400 and you utilize the motor at 100-200 RPM most of the time, a smallish controller may overheat.

 

[Pegasus195]

The only problem could be if motor is geared too fast at a given voltage and controller is forced into PWM all the time.
Say if your no load RPM is 400 and you utilize the motor at 100-200 RPM most of the time, a smallish controller may overheat.

Even though it will overheat, do you consider it "safe"? Or maybe you have tried it before?

 

[dustNbone]

It will work fine provided the phase/hall wiring is correct, but as stated above if the motor ends up spending alot of time far below maximum speed the controller will get hot. High amps at low speed is thermally hard on the controller, and by extension efficiency suffers.

It's not going to cause any immediate failure though, the watt limits on the motor and controller don't have to match either way, but the lower rated component will generally suffer from more heat.

A 500W motor with a 1500W controller will work too, but the motor is likely to get hot if you try to push that much power through it. It won't fail immediately, but you'll really want to monitor temperatures.

Give it a try, get the wiring right, see if it gets too hot. Immediate catastrophic failure is very unlikely.

 

[Punx0r]

It's important to note that running a motor slowly is only a problem if it's also at high load. Running it slowly just because you're riding slowly on flat ground is absolutely fine.

 

[Pegasus195]

It will work fine provided the phase/hall wiring is correct, but as stated above if the motor ends up spending alot of time far below maximum speed the controller will get hot. High amps at low speed is thermally hard on the controller, and by extension efficiency suffers.

It's not going to cause any immediate failure though, the watt limits on the motor and controller don't have to match either way, but the lower rated component will generally suffer from more heat.

A 500W motor with a 1500W controller will work too, but the motor is likely to get hot if you try to push that much power through it. It won't fail immediately, but you'll really want to monitor temperatures.

Give it a try, get the wiring right, see if it gets too hot. Immediate catastrophic failure is very unlikely.

But shouldn't motor controller be able to adjust the amount of amps coming out to the motor, just like how it can adjust the wattage with a speed switch that limits the amount of amps coming out of the controller too?(correct me if I'm wrong)

 

[dogman dan]

The controller cannot adjust how hungry a larger motor is. It's much more copper, big magnets. It wants to draw big watts. The big motor will pull and pull and pull before back EMF lessens the pull as you speed up. The small motor, it backs off much sooner, so the load on the controller is less, even though both may still end up at an identical cruising speed. I might be dead wrong about why this is so, but you can see it big time on your watt meter. The small controller on the big motor pulls max amps much longer. But if max amps is higher, the motor gets going quick, and barely pulls ( the higher) max amps at all. So both might pull 20 amps for about the same time, but with one controller its a breeze, and with the other it is maxing out the whole time.

It should not blow your controller,, we are not saying that.
With the small motor, back emf is reached sooner, and the motor stops being quite so hungry. So it doesn't run full amps of the smaller controller as long, doesn't get as hot.

This may matter, or not, depending on the type of riding you are doing. Hard riding, like off road, or an overloaded trailer, needs the bigger controller to pull a big hungry motor.

 

[Pegasus195]

The controller cannot adjust how hungry a larger motor is. It's much more copper, big magnets. It wants to draw big watts. The big motor will pull and pull and pull before back EMF lessens the pull as you speed up. The small motor, it backs off much sooner, so the load on the controller is less, even though both may still end up at an identical cruising speed. I might be dead wrong about why this is so, but you can see it big time on your watt meter. The small controller on the big motor pulls max amps much longer. But if max amps is higher, the motor gets going quick, and barely pulls ( the higher) max amps at all. So both might pull 20 amps for about the same time, but with one controller its a breeze, and with the other it is maxing out the whole time.

It should not blow your controller,, we are not saying that.
With the small motor, back emf is reached sooner, and the motor stops being quite so hungry. So it doesn't run full amps of the smaller controller as long, doesn't get as hot.

This may matter, or not, depending on the type of riding you are doing. Hard riding, like off road, or an overloaded trailer, needs the bigger controller to pull a big hungry motor.

Thank you for the reply, It helps my concern for my bike