Motor much noisier after controller replacement

[marshy]

I've recently replaced my controller and suddenly, sadly, my motor became much noisier. I thought that was interesting because there seem to be conflicting reports on E-S about motor X being quieter than motor Y - could an important factor be the particular controller?

Motor is a rear sensored Bafang (20" model - 300 rpm in 700C). Original controller was one of BMS Battery's first 6 FET models. I remember reading in the description before I purchased that it had some sort of claimed smooth power delivery. It would accelerate the motor quietly, maxing out at 480W or so, and when cruising the motor was effectively silent. My new controller, another 6 FET model, starts off fairly quiet, then suddenly becomes louder at about 5-10km/hr. At about 50% of no load speed under full throttle the motor quickly gets very angry - a sort of resonant power peak. This dies away fairly quickly above 20km/h. At cruising speed of about 32km/hr, it's not what you'd call loud - like a small swarm of bees chasing me. However with my old controller, the motor could barely be heard at that speed...it was much quieter through the whole range.

What makes a motor noisier with one controller versus another? If I want a quiet motor, which controller models/suppliers are best?

 

[MadRhino]

A motor shouldn't be noisier with a different controller, unless it feeds much more power.
You might have a corrupted hall signal, or a false positive phase combination. That can make a motor noisy, normally with a loss of torque.

 

[cassschr1]

What happened to make you replace it?

 

[miuan]

My motors have been slightly more silent with ecitypower controllers too, compared to 846, 112 and 116 infineons that I've had.
I have no clear idea why, but it may be different phase timing.

 

[dogman dan]

There can be differences. But as MR says, if it's making more noise it's real likely the reason is more watts are reaching the motor at that point. The race track controllers make a motor howl!

In your case, the controller may ramp up the watts a bit more abruptly than your other one did.

 

[marshy]

What happened to make you replace it?

It had been playing up - cutting out for some reason now and then and needed to be powered off before it would go again. One day seemed to give up the ghost - cant remember symptoms exactly - but that prompted me to replace it.

I resurrected that old controller today. It worked, but kept cutting out under full throttle. If I eased off the throttle and reapplied slowly it would spring to life again. Perhaps it was hitting its low voltage cutoff. Wattmeter said Vmin was 28.6V. Pack is 36V lifepo04 so that seems a little high for LVC? Charging my battery for a retest tomorrow.

Anyway, back to main topic - the motor ran *VERY* nicely with this old controller. Almost night and day. No harshness. No angry growls yet smoother and more powerful. It peaked at 420W, 14.9A. My new "noisy" controller only has a 12A limit so ironically despite the extra power the motor is noticeably quieter with the old one. Like having a new and MUCH better motor.

I have a Keywin 350W sensorless controller as well. It's a spare and I hadn't got around to using it. Thought that would be useful as a reference. Ran ok at no load but under load would oscillate slowly and max out at 180 or 200W - so it was kind of quiet I think it's sick.

I'll do some more testing. Keen to determine if the old controller is particularly special, or the new one is just plain dodgy. The thing is, if I had no other controller to compare to I wouldn't have thought the new one was too noisy. I wonder if others have unnecessarily noisy controllers.

The old controller appears to be made by these guys. http://www.persino.com/www/en/pro/parts/con-brushless.asp. I got it from BMSBattery/ecitypower (one of their first ever customers) but seems they use other supplier(s) now.

However...from the pics and model numbers the evassemble controllers appear to be made by Persino. Can anyone confirm they are beautifully quiet?

 

[d8veh]

In my experience, there's a direct relationship between the noise of the Bafang 250w motors and the power of the controller. Nothing to worry about! Try soldering the shunt for a bit more power for hill-climbing and you'll hear the noise increase further.