Electric Motor Noise

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Michigan Mike

Michigan Mike

New Member
Dec 9, 2008
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Michigan
I just did a search on "electric motor noise" but didn't find any related threads ...

Can someone please tell me why some electric motors are extremely noisy and others are quiet?
Which e-bike motors are quiet?
Thanks.
.trk.
 
deacon

deacon

minor bike philosopher
Jan 15, 2008
8,114
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north carolina
You know thats a good question. I have three motors exactly alike and the all have a whine. High pitch whine for some reason except for today. Today I hooked a 350 controller to the 600 watt motor and it is as quiet as a mouse. Totally strange I know.
 
Michigan Mike

Michigan Mike

New Member
Dec 9, 2008
509
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Michigan
I was surprised to read in another thread how loud some ebike motors were. I think someone said his was louder than a gas motor. ?
 
professor

professor

New Member
Oct 14, 2009
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Buffalo ny area
I was ready to buy an e-zip until I watched some videos on Youtube and a video comment about dogs barking a couple blocks away from the noise.
Some people aren't bothered but it would drive me nuts.
The Currie motors drive a straight cut gear reduction box and those gears scream. I would say, anything with gears would be noisy- I am using an electric scooter motor with a chain drive (thinking about friction drive instead) and it makes a little noise. Don't know much about the hubmotors.
 
deacon

deacon

minor bike philosopher
Jan 15, 2008
8,114
9
0
north carolina
I have a hub motor stored in the shop. It was fine when I got it but I had to replace the controller an now it sounds like it is going to lock up any minute. I might put it back on a bike one day. It is pretty loud, but it wasn't before I changed out the controller.
 
J

jdcburg

New Member
Jul 9, 2009
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massachusetts
They say brushless are almost silent. I have a brushed Unite 1016Z3 with a gear reduction unit on it. It has a gear whine under power. It sounds like an electric drill. However if it's on but not supplying power to the wheel (like going downhill), I can barely hear the motor over the wind noise - jd
 
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T

TheE

New Member
Jun 26, 2009
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Canada
A high pitched whine can actually be caused by the PWM of the controller. The current turning on-and-off causes the windings inside the motor to expand and contract at the frequency of the PWM signal, creating waves in the air and thus sound. Some controllers might bump the PWM frequency up past 20kHz so the sound is impossible to hear.

I guess you'd have to check the output of the controller with a frequency counter to know for sure. It very well could just be the gears.
 
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