Motor run-on?...

[chossy]

Hey,

I was out around Aviemore yesterday, brand new haibike, I was bouncing down a loose rocky trail nothing crazy. I stopped as I heard a whirring noise... it was like the motor was just running away with itself. So I removed the battery... errr the motor kept going with no discernable change. So I put the battery back in and after bouncing down about another 20/30m the whirring stopped.... WTF was that all about...
Has anyone any idea what it might be? a huge amount of inertia and a disengaged clutch?

 

[Mikerb]

Well....first principles...an electric motor cannot run without a supplied electric current. So if indeed it was the motor making the noise even with the battery removed it must have been getting voltage from somewhere....perhaps a capacitor which would be part of the pcb in the motor. The only way I can see that happening is if the clutch/sprag bearing in the motor did not disengage as you freewheeled down the hill so you were in fact driving the motor.

 

[steve_sordy]

Whatever it is, I'd get it looked at.
You should always pay attention to weird noises until you have a convincing explanation. Then get it fixed!

 

[chossy]

Just to clarify the bike was stationary for a good minute with the battery out, bike just lying on its side. It must have been some crazy inertia. I'll get in touch with haibike.

 

[steve_sordy]

The good news is that internal friction must be low!