Does DC-controllers normaly current limit?

[sandos]

I am new to owning any electric vehicle, my dad gave me this chinese e-scooter that I assumed was 1000W, since thats the lowest legal limit here in Sweden (unless for e-bikes which I think is still 20kph/200w). But the controller is marked 36V/15A, and it is very, very powerless. A very small incline or just holding the scooter lightly with feet is enough to make it not start from a standstill.

My real question though is, this 15A limit is something that the controller enforces by reducing PWM duty cycle? I thought it was a "never exceed" rating but I am starting to question that.

 

[amberwolf]

My real question though is, this 15A limit is something that the controller enforces by reducing PWM duty cycle?

Yes, usually.


But even 15A at 36V is normally enough to get and keep going, so I would guess your batteries are just old and worn out (or otherwise incapable of supplying the power being demanded of them).

 

[sandos]

My dad claims the batteries are new. Wouldn't the voltage sag if the batteries were bad? The pack barely drops a volt when its stalling, seemed good to me but I am used to RC cells.

The controller seems to have some burnt components, at least one resistor is blackened. I also tried driving the motor with a 12V power supply and it seemed much torquier, although I was just trying to brake the wheel in the air.

 

[sandos]

I measured the current when stalling the wheel from stand-still by hand, to ~12A which is at least not extremely wrong. The motor is marked with, I think, 18A.

My next experiment would be to connect 1, 2 and 3 batteries without PWM directly to the motor but I don't have any switches that can handle the job. I do have a FET but I would need to handle back-EMF and I dont think I have the components for that.