Humming noise 4 pole motors

[faico_26]

Hi,
This video shows the humming noise Quickie 4 pole motors have. My Q300R does it too. I hate it.
https://youtu.be/ydjoek4iBR0?si=jjO31EChRy0dosx4

[Burgerman]

Why? I cant say I ever notice or care.

Most 4 pole motors are noisier han 2 pole. Because they have more "pulses" per revolution. And so more power or torque. The armature has x number of iron sections in the core. These are attracted to the magnets as the motor turns. If the same armature is used on a 2 and a 4 pole motor (they usually are or at least very very similar) then theres double the number of magnetic "attractions" per revolution. So a 2 pole motor would make the "same" frequency of sound or have the same number of pulses at double the RPMs.

Heres whats in your motor.

The magnets and iron cores attract each other.
The 1st is what you see on a small motor in a "toy" or something cheap. With 2 poles and three iron poles and 2 magnets, 2 brushes. A two pole motor. The 2d one is whats really in your motors. There are many iron sections. And 2 or 4 brushes, and 2 or 4 corosponding magnets.

[faico_26]

Why? I cant say I ever notice or care.

Most 4 pole motors are noisier han 2 pole. Because they have more "pulses" per revolution. And so more power or torque. On a 2 pole motor the poles happen every half a revolution, and they build gradually and then "release" gradually. With 4 poles then that happens more suddenly and twice as frequently.

Well, I’m used to silent 2 pole motors and i really feel the 4 pole very noisy mainly indoors. There’s really a big difference. And the 4 pole are rougher in small slow movements when you need precision for example to put the chair in a very small space.
For what I’ve seen I would say Sunrise Quickie 4 pole motors are noisier than other brands like for example Invacare, but I’m not sure.

[Burgerman]

Well they may be noisier. But sunrise dont make motors. Those are Linix a chinese brand same brand as permbil and many others use.

A 2 pole, all else equal has higher RPM and less torque. And can be more efficient, quieter, and smoother as theres less distinct "cogging" as it turns.
A 4 pole is generally noisier, double the torque if everything else is the same, and half the RPM.

A 4 pole really refers to the number of magnetic poles. And a 4 pole motor can have just 2 brushes. We dont see that often on chairs though so 4 poles are easy to identify as they have 4 brushes. Because we manoever at low speeds, we need high torque in a small package. So 4 pole is generally better. Especially in a 4 brush motor as twice as many magnetic cores or "lobes" are active at any given time. So theres double the number of magnets and active windings in action all the time. That means half the impedance, double the current. So more torque. Because theres two sets of magnets active all the time, we feel those pulses at super slow speeds. Where I just dont care. And we HEAR the motor more as it has double the amount of pulses. So it sings!

You must be super sensitive to this compared to me. Its something that I hear and couldnt care less frankly! I never notice it.

Take a listen to how a 4 pole motor (AMT in this case) sounds at 45V and around 10,000rpm instead of 5000 as it normally is on 24V.

Turn up the sound.
Sounds like a 4 cylinder silenced motorcycle engine.

At the end. 1 min 20 secs...

https://www.wheelchairdriver.com/gopro/RC-BM3.mp4

[Burgerman]

4 pole is same as 2. Just uses FOUR magnets, and has FOUR brushes, and double the number of activated windings at any given time.
So its literally 2 motors in one casing...

You FEEL that as twice the magnetic pull. Or twice the strength of that magnetic pulse. You HEAR it for the same reason. The motor wants to turn in distinct strong 90 degree phases. 1234 per revolution.

Unlike a car or bike engine with 2 or 4 cylinders they all fire at the same time! But twice as often.

As for precision in small spaces the 4 pole is actually BETTER not worse as it has more torque and so ignores extrernal forces like casters positions or carpets etc. You may FEEL the individual magnetic notches but positional accuracy is truly better. As long as your chair is programmed properly and motor compensation is set high enough and turn acceleration/decel is set high enough. Like all 4 min, max, acc and dec to 100. And Torque is CORRECTLY set to match compensation.
Why? Because theres twice as many "notches" per motor revolution that the motor wants to settle into. And many hundreds per wheel revolution.

At which point its millimeter perfect and totally predictable regardless of carpets, casters etc.

[faico_26]

Yes, I’m still trying to get the proper programming for my chair. I feel the chair very slow, lazy, on carpets or grass.

[Burgerman]

Thats because it needs me to tweak it!

I just added a CORRECTLY configured profile to magic V6 chair...

By PM.

Sent: Sun Jan 11, 2026 2:06 pm
by Seafighter
WOW! The steering is absolutely amazing!
I never understood the need for five different profiles.
it is so much better just to push the joystick to match the speed you want to make the chair go.



No more hovercraft mode!!!

[Seafighter]

That was a little over a week ago and the difference is truly amazing. The chair is so responsive it quickly goes exactly where I want it to go. Haven't hit a door jam since the re-programming. Also, hiding the other 5 profiles means I can go from the speed profile to the seating changes with only on toggle movement instead of 6. The chair is so much more enjoyable to use I wish I didn't have to get a new one. At least I will have a great back up chair. Thanks Burgerman!

[Burgerman]

I have been telling people this for years. One in a hundred gets to find out! Ater that, you are "recalibrated" and nothing else is any use.

And this is the very reason that one of the list of requirements for any new chair (theres a bunch!) is that before I even consider looking at it, I MUST be able to get and own an OEM level programmer for it. No programmer? That rules it out from the getgo.

[faico_26]

Hi BM,
I see that you have a Q700R (nice with those tyres). And watching the pictures of your chair i can see they are 4 pole motors. I guess these are the same motors I have in my q300r. As you may remember, my motors make a humming sound which is due to the 4 poles. But worse is that my motors stall with just 3cms curbs. I have 90amp VR2. And i see that you have R-Net, is it 120amp? Can you climb curbs or it also stalls?

[faico_26]

Hi BM,
I see that you have a Q700R (nice with those tyres). And watching the pictures of your chair i can see they are 4 pole motors. I guess these are the same motors I have in my q300r. As you may remember, my motors make a humming sound which is due to the 4 poles. But worse is that my motors stall with just 3cms curbs. I have 90amp VR2. And i see that you have R-Net, is it 120amp? Can you climb curbs or it also stalls?

[Burgerman]

Well I never noticed any hum. Curbs? Well it depends on the curb. Not much different to all my other chairs. But I have rear bias, higher motor compensation setting (50), and 120A power module so with correctly set compensation at least 30% or more additional power. Also low impedance battery. But mostly I dont use that chair. So quite hard to remember!

[Burgerman]

And...
Q700 6.2mph

Motor, 4 pole, 10kph, Motor P/N: 241114 RWD = right, MWD / FWD = left, (Identify the order number via the P/N on the motor)
Motor, 4 pole, 10kph, Motor P/N: 241115 RWD = left, MWD / FWD = right, (Identify the order number via the P/N on the motor)
Motor, 4 pole, 10kph, Motor P/N: 250288 RWD = right, (Identify the order number via the P/N on the motor)
Motor, 4 pole, 10kph, Motor P/N: 250289 RWD = left, (Identify the order number via the P/N on the motor)
Motor, 4 pole, 10kph, Motor P/N: 250286 MWD / FWD = left, (Identify the order number via the P/N on the motor)
Motor, 4 pole, 10kph, Motor P/N: 250287 MWD / FWD = right, (Identify the order number via the P/N on the motor)



And 8 and 8.5mph, 13kph:

Motor P/N: 250292 RWD = right, (Identify the order number via the P/N on the motor)
Motor, 4 pole, 13kph, Motor P/N: 250293 RWD = left, (Identify the order number via the P/N on the motor)
Motor, 4 pole, 13kph, Motor P/N: 250290 MWD / FWD = left, (Identify the order number via the P/N on the motor)
Motor, 4 pole, 13kph, Motor P/N: 250291 MWD / FWD = right, (Identify the order number via the P/N on the motor)
Motor, 4-pole, 13kph, Motor P/N: 241238 RWD = right, MWD / FWD = left, (Identify the order number via the P/N on the motor)
Motor, 4-pole, 13kph, Motor P/N: 241239 RWD = left, MWD / FWD = right, (Identify the order number via the P/N on the motor)

[faico_26]

Very useful list, thank you.
My chair gets 9km/h not more. I have 12,5” rear tyres. I tried another q300r with 14” tyres and the same motors and the speed was the same. I also tried another q300r with 2 pole motors and it reached 10km/h.
My motors are 163rpm and the 2 pole motors are 175rpm.

[Burgerman]

>>>My chair gets 9km/h not more. I have 12,5” rear tyres. I tried another q300r with 14” tyres and the same motors and the speed was the same.

Not logical. How are you determining speed?
12.5 + 12% increase in diameter and rolling distance is 14 inches... So it will be 12% faster approx. In reality about 9% because of the following...


Also that rpm figure at 22.5V is quite useless. It tells you only rpm per volt in a free running unloaded motor. Real speed OR RPM depends on load, actual voltage reaching motor, and losse which is determined by motor impedance, battery or wiring impedance, rolling resistance, so tyre diameter and even pressures, your and the chair weight, CG position, how level the surface is, temperature of motors, batteries and battery type as well as programming. Remember a bgger wheel increases load all else equal by 12% too.

For e.g a lower impedance motor may have lower free running rpm, but will respond better to compensation, will automatically draw more current as you load it anyway, and will slow less under rolling loads. But may/need a lower impedance battery or controller/wiring to do so. Or that battery voltage falls more under a load at the motor terminals.

Lets say for the sake of understanding this you fitted a motor that was much smaller like one from a hairdryer or a toy. It turns much faster, say 25,000 rpms. And is also much higher impedance. So draws much less current. Will the chair go faster? No because it doesent draw enough current to make enough torque (its impedance is way too high) so the chair likely will be super slow or wont even move. If you lift the wheel off the ground then it will spin very fast!

[faico_26]

>>>My chair gets 9km/h not more. I have 12,5” rear tyres. I tried another q300r with 14” tyres and the same motors and the speed was the same.

Not logical. How are you determining speed?

Also that rpm figure is quite useless. It tells you only rpm per volt in a free running unloaded motor. Real speed depends on load, voltage, etc which is determined by motor impedance, battery or wiring impedance, rolling resistance, so tyre dia=meter and even pressures, your and the chair weight, CG position, how level the surface is, temperature of motors, batteries and battery type as well as programming.

For e.g a lower impedance motor may have lower free running rpm, but will respond better to compensation, and will slow less under rolling loads. But may/need a lower impedance battery to do so. Or that battery voltage falls more under a load.

Lets say for the sake of understanding this you fitted a motor that was much smaller like one from a hairdryer or a toy. It turns much faster, say 25,000 rpms. And is much higher impedance. So draws much less current. Will the chair go faster? No because it doesent draw enough current to make enough torque (its impedance is way too high) so the chair likely will be super slow or wont even move. If you lift the wheel off the ground then it will spin very fast!

I measure the speed with an app in my phone.

[Burgerman]

Those are only accurate to about 1mph over a sensible distance. Your chairs speed varies for lots of reasons. So if its half a mph faster at your 6mph then it will be hard to measure it accurately. As thats 10 full percent = .6 of a mph.

If you really want faster you need a set of Motor P/N: 250292 and 250293 and a 120A power module with good low impedance battery. Correct programming.
If you prefer torque (curbs) you need the motors you already have with the 120A module and programmed properly.

[Burgerman]

These... On my shelf!

[Burgerman]

Yes I know. Different part number again! These are JIVE motors. And 35mOhms.

They are a replacement service part for the 45mOhm AMT ones below on my bed!

Theres a lot of different motors.

[Scragger7]

About to have my 4th set of motors replaced on my Q700r. So bloody noisey.

[Burgerman]

Do you mean noisy because of a fault or noisy just because they are working and making a normal sound?

Lots of people complain of noisy motors. Personally I dont care one bit or really notice much as long as its healthy. Mechanical things with brushes, armatures, gears etc make do make noise when they work. Like a drill or a vaccuum cleaner, a food mixer, a lawnmower. When new they are all tight and quieter. As they wear or run in, they develop clearances in bearings and gears etc and so are louder and thats just normal. You might get 10% inital life where quieter. 90% where they get gradually louder and still perfectly healthy. And then 10% where they develop very clear abnormal fault noises at end of life to warn you of imminent demise.

Thats the nature of all mechanical things.

[Scragger7]

Do you mean noisy because of a fault or noisy just because they are wereworking and making a normal sound?

Would not be replacing them if they were "working and making a normal sound"

[shirley_hkg]

I'd watch out for abnormal rise of temperature.

[Burgerman]

So whats the fault?