MP 2 Humming noise at low throttle

[luvxu]

Hi all,
I have been running my MP2 with Lyen 12 fets controller for a week now. It ran silky smooth at high throttle but motor giving out this noisy humming sound at very low throttle, say 1/8 of throttle. I wonder if anybody know what that is? I have a 48V 20Ah battery and the MP2 give me plenty of torque and speed at high throttle. I just wonder what is the noise at low throttle and is there anything I could do to make it goes away.

Thanks for your help.

[truly_bent]

Post a video on Youtube. Or maybe attach a sound file.

I don't know what constitutes "noisy humming" in your book, but the MP does have a distinct sound when running at low speed. The motor will never be silent at low rpm and it does seem to fade into the background at speed. Might be the Doppler Effect as I approach the speed of sound though.

Have you asked Edward "The Magician" Lyen?
Jeff

[luvxu]

ok, here is a video to show you what I meant http://youtu.be/OxvdwQlmBt8

Note that this noise disappeared when the throttle is increased above the 1/8th threshold. The motor operated smooth and strong then.

[truly_bent]

Ain't technology grand?
You can just pop a vid into the Cloud and get almost instant feedback - from some idiot saying he can't help you. You could have saved yourself the trouble.

It sounds as though the FETs are going through the motions. This looks like the controller is running (or trying to run) in sensorless mode. Do you have the Hall Effect sensors connected?

Jeff

[luvxu]

In trying to fix my slightly annoyed low throttle sound, I encounter a much bigger problem now. I found that my wiring combination has a high no-load amperage, around 20A. So I tried a different combination recommended by other forum member. However, I also reprogrammed my controller and now my bike is running slower than even a walking old lady.    Please see this thread http://goldenmotor.com/SMF/index.php?topic=4533.0

Update to let you know that the problem is fixed. Lyen informed me that my 12 fet board should be programmed like the 18 fet board because of some modification that he made to the shunt resistor. Now the motor is running strong again and the humming noise at low throttle is also gone.