Two pole motor

[ICEUK]

Just had a demo in a two pole motor chair, what a dog. It does not even move if you push the joystick all the way to the side when you are on carpet. I dont understand how ppl accept a two pole motor, its utter @#7*@

[Burgerman]

Generally half the torque, double the impedance, double the brush load so carbonised and ruined faster.

Theres no actual physics reason that 2 pole has to be worse. Its down to the way wheelchair modors are made. Remember that horid thing, "modular"?

They take common 4 pole motor, inc commutators, bearings, brushes, brush holders, gearboxes, motor casing, cush drive, etc.
And then make a cheaper motor with just 2 magnetic poles (north/south magnets). And with just 2 brushes. Its all about $$$$.

So as a generality, the 4 pole motors are extremely similar. Visually the only changes are 2 extra brushes. Internally 4 magnets in place of 2. That does not mean that you cannot build a very powerful 2 pole if you want. But thats not what we see.

Interestingly this does not change motor watts. Because thats not a measure of motor power, only the highest amount of watts it can sustain without overheating CONTINUOUSLY. But the 4 pole has twice the current at the same voltage, so double the torque. Because the SAME torque and Amps happens at a lower motor voltage efficiency is increased with 4 poles too.

[wheelie junkie]

Could it be down to programming? Where did you demo the chair?

[ICEUK]

I demo it in my home, it was ok accerlerating but if you asked it to turn on spot it was awful, full deflection on joystick. U had to nurse it around to get it moving ie go forward first then start to turn utter cr ap

[rover220]

what chair was it?

[Burgerman]

It could also be that the controller was low amp output. Its why I always buy 120A or 100A and 4 pole.

And yes, what chair?

The permobils are 2 pole at 7.4 mph. And lack a bit of torque. They are basically the same 2 pole as used on the salsa chairs with a different gearbox style. Made by linix in china. Also remember that user weight/seating weight matters here. And that a rear or front drive needs a lot more torque to zero turn than a mid drive.

Depending on the chair order form, the chair you demoed could likely have an option for 4 pole, and a higher output controller. And remember that an 8mph chair will have l fair bit less torque than the same 4 pole motor with a 6mph speed gear ratio. And that most 2 poles, have adequate torque at 4mph. 6 or 7 is pushing it too far.

[ICEUK]

It was a q500r, had a rnet joystick but i dont know what amp the power module was.

[foghornleghorn]

This thread is confusing. Q500R is supposed to have 4-pole motors.

[steves1977uk]

The order form states 4-pole motors for RWD, so how did you end up with 2-pole Ice? Either that or they fitted a low powered 60A R-Net PM which would lack power to turn on carpets.

Steve

[ICEUK]

It was a demo, i can only tell you what it had. Two pole pile of dung.

[LROBBINS]

Are you sure it wasn't just programmed with too little motor compensation (and if RNet, torque)?

[ICEUK]

Its possible lenny, but a demo chair that dont turn on the spot is not really a good way to sell stuff..

[Burgerman]

The other thing is that few will either have an OEM level programmer and that includes dealers, or understand the problem. If that IS the problem. The stock controller is 90A. Should be OK ish on a 6mph chair. If its 2 pole, then probably not as they are very nose heavy.

But this is what you see on almost every rear drive chair. Nobody seems to get it. They all sit you too far forwards over the front casters. Then they need a ton of power to initiate a turn in place. And instead of fitting 4 pole motors, and powerful controllers they fit the weedy controllers and 2 pole motors specified by the bean counters.

What they MUST do to make it work, is move the seat back. 2 to 3 inches is not much but makes a massive difference.
And in order to do this you need a centre footplate. And the caster wheels far enough apart to allow your heels to fit between them.
And fit 4 pole. And the 100 to 120A controllers.
Then it all works great. But thats not how they are sold.

Hence viewtopic.php?f=2&t=7455&start=600#p122818 which turns great with my 20 stone in it.

[Mechniki]

Just had a demo in a two pole motor chair, what a dog. It does not even move if you push the joystick all the way to the side when you are on carpet. I dont understand how ppl accept a two pole motor, its utter @#7*@

Question : Did you rely on the sales pitch, or did you check the caster stems were loose and the wheel bearings freely rotating?

My reason for asking, I have two Roma Marbella's both have 2 pole motors and they have no problem turning on carpet. I have just replaced the caster bearings on both plastic caster wheels, as one side developed an odd noise last Thursday. I replaced with ABEC 11 RS and glued them in with bearing fit. It now turns even better.

[Burgerman]

Is it 4mph?

That means that it has 1.5x the torque of a 6mph chair at any given Amp level. A 50% gain. And its a very lightweight portable chair without all the heavy seating.

[rover220]

Is it 4mph?

That means that it has 1.5x the torque of a 6mph chair at any given Amp level. A 50% gain. And its a very lightweight portable chair without all the heavy seating.

if a 4 pole motor then sunrise 4mph is usually just a programmed down 6mph.

[Burgerman]

We were talking about this one:

My reason for asking, I have two Roma Marbella's both have 2 pole motors and they have no problem turning on carpet. I have just replaced the caster bearings on both plastic caster wheels, as one side developed an odd noise last Thursday. I replaced with ABEC 11 RS and glued them in with bearing fit. It now turns even better.

Which is a 2 pole, but has power to turn because its geared for 4 mph. Which gives it 1.5x the torque of a 6mph motor all else equal.

[Scooterman]

All things being equal, which lasts longer/more reliable: 2-pole or 4-pole?

[Burgerman]

4. Because its the same motor, with half the brushes.

In a 2 pole motor, each brush takes double the Amps all day long. They burn, wear faster because of that.

If a 2 pole was designed with a lower impedance, and a bigger brush, then it would perform the same as the 4 pole. But thats not what they do or not what we see. Because that would involve manufacturing 2 different motors. $$$$$.

[Mechniki]

Is it 4mph?

That means that it has 1.5x the torque of a 6mph chair at any given Amp level. A 50% gain. And its a very lightweight portable chair without all the heavy seating.

It's 4.5 mph
I think because the tyres are 14 inches (8 inch rim)
The brushes are not much to look at, on the original, though my other Roma I replaced the brushes with a pair of starter motor brushes for a 3.5 L Ford Transit (just after the chair was out of warranty). Unfortunate that Halfords has gone from Dorking. I expect to get new brushes now will mean scouring the Internet.
When I got the chair new in July last year, it came with spare motor brushes and I would not use them unless I was stranded, piddly little things

The previous Roma was an Ex Demonstrator so was missing stuff and had a limited warranty

[Scooterman]

4. Because its the same motor, with half the brushes.

In a 2 pole motor, each brush takes double the Amps all day long. They burn, wear faster because of that.

If a 2 pole was designed with a lower impedance, and a bigger brush, then it would perform the same as the 4 pole. But thats not what they do or not what we see. Because that would involve manufacturing 2 different motors. $$$$$.

Thanks BM, got it

[ex-Gooserider]

Two pole motors aren't great, and certainly aren't up to BM specs, but they aren't totally horrible IF PROGRAMMED PROPERLY....

The described symptoms sound more like a programming issue...

I remember posts from a long time back where BM had found that Pilot+ controllers on some Sunrise chairs had the same motor compensation values set for both 2 pole and 4 pole motors - since a 2 pole has higher internal resistance, setting it to a 4 pole value will give crappy performance on rugs and so on....

ex-Gooserider

[Mechniki]

I remember posts from a long time back where BM had found that Pilot+ controllers on some Sunrise chairs had the same motor compensation values set for both 2 pole and 4 pole motors - since a 2 pole has higher internal resistance, setting it to a 4 pole value will give crappy performance on rugs and so on....

ex-Gooserider

Could a 4 pole motor survive being set up as a 2 pole motor?

[Burgerman]

Its not about surviving. Its about control.

Typical 4 pole is set up as a 45 to 50mOhm.
A typical 2 pole can be 70 to 130 or even more.

So if your PM is set up for a 4 pole motor (say 45) and you fit a 2 pole in its place the chair will be gutless, sluggish, may fail to turn in place or move when set to a low speed.

If its the other way around, and your PM is set to say 70 or more, then you just fit a 4 pole, then the chair may be ultra snappy and jumpy. iMPOSSIBLE TO CONTROL IN ANY NORMAL WAY.
But equally it may run away and cannot be stopped no matter what you do with the joystick. Think broken legs or worse.