Quickie Groove 8mph motors. Any good?

[Burgerman]

Considering fitting a set of 8mph Quickie groove motors to my letest powerchair.

http://www.wheelchairdriver.com/ultimat ... rchair.htm

Tried several 8mph motors in the past on my chairs. Lack of torque, and short battery range were the result in all cases. But I accept that and its a known quantity. (I have a sort of fix for that but I digress..,)

But what about strength when abused/reprogrammed etc? And does anyone know the measurements of the motor (diameter) as I dont want to go wider than 90 mm... Thats what the ones I am using now are. It lets me keep to 25.2 inches even with huge fat tyres. Space (overall width) doesent allow that 90 to be any greater...

(Along with a dynamic 90 amp, or 120 amp penny and giles R-net controller to replace the 100 pilot plus existing. With the dynamic being superior as we already know.)

[JoeC]

I haven't been able to find any information on who manufactures them, but you should make sure that they are not the Electrocraft motors normally in the S646SE and newest P222SE. Those motors provide good torque, but suck battery pathetically- even the 7.0 mph geared version!

This past weekend one of my players brought his new P200 to practice, and I swapped his Yellowtop batteries from the S646SE to the P200. Generally, the S646SE would have drained his batteries to nearly flat during the the two hour practice. With the same set of batteries and the same 200+ pound user, the battery meter was only down by one light. Programmed acceleration was all the way up, and he was getting much better performance out of the chair.

I'm sorry if I sound like I'm always preaching about the P200 and how great it is for sports, but I think it's a valid indication that the Electrocraft four-pole motors are inefficient battery hogs when put to serious use. If you try the Groove motors, make very sure that they aren't a repackaged version of the ones used in Quickie's other chairs!

[Burgerman]

Intersting. How can I know? Small change inside (say magnets) and efficiency changes drastically...

If you were to put a set of 8mph motors on my chair (fat bloke off road, steep ramps. wheelies everywhere like a loony etc) which 90 degree ones would you choose? And where would I get them from? (biggest poss controller will be fitted)

Thing is (as you likely already know) lead batteries like the optimas can be fast charged in about 1 hour to 95 percent. I do the same with MK Gels too (although they take about 30 mins longer as the voltage gets dragged up to the 14.4v limit early due to internal resistance so current falls sooner) and have been doing this for years. I charge them also directly from the vans 100 amp 14.4v alternator if I am out somewhere fast if needed.

See http://www.wheelchairdriver.com/wheelch ... ectors.htm

One to each battery. And one to my van. Do one at once... Or smoke!

So range isnt really an issue for me. Why do wheelchair manufacturers still send tiny little chargers out?

So P200 motors... How much, 90 degrees? and where from if they are geared right for 8 to 9 mph? (14.5 inch wheel diameter)...

If not which ones?

[JoeC]

Right angle is very problematic. Worm gear efficiency is a function of load and speed, not just ratio, so although your EMD worm gearset may say that it's 90% efficient, that would be the best case scenario.

http://www.roymech.co.uk/Useful_Tables/ ... iency.html

Worm efficiency is at its lowest (dropping as low as 60% in this chart) when it is highly loaded at low speed- when you're accelerating up a ramp or climbing a hill. I don't know if the motor or the gearbox in the Electrocraft motors are the weak point, but I have a suspicion that the gearbox is a lot worse than in-line spur gears.

If I had to pick the best right angle gearmotor, and had to use a worm, I would look for something with a high RPM and high ratio. Otherwise, I would look for one that uses a miter or bevel gear to make the 90 degree turn. I'm sorry to say that I haven't found one that fits the bill yet. The ASI Drives ADL200 looks close, but I have only ever seen it mounted on grossly underpowered motors, on the case of early P222's, a three phase AC motor: http://www.asidrives.com/pdf/ADL200.pdf

The P200 motors turn at about 250 RPM at full speed, and are typically used with 10 inch wheels. You would need to do something different to use them with 14 inch wheels, or you'd be geared for over 10mph. The two-stage spur gear reduction is probably in better than 90% efficient across its useful range, possibly as high as 95%.

Since you posted your experience with chain drives, I've been looking into timing belts. This is the website I've been visiting: http://www.gates.com/index.cfm?location_id=534

[Burgerman]

These below are the ones claimed to be 90 percent efficient (under load see charts) that I stripped and rebuilt. They are pretty high ratio. Which increases efficiency I suppose.

These are actually from some weedy 2 pole motors but the 4 poll ones look the same but more substantial.
These are as far as I can be sure (and I have tried very hard) to be unbreakable even when connecting the 24v via a relay rather than through a limiting controller.

The nylon (delrin?) is actually better than steel or bronze as its slightly compressible meaning tighter running clearances can be used and less noise/backlash. And its lighter too. And unmeasurable wear even after 13 years of abuse. The bearings wear first on the input shaft! And they are cheap. Although someone on here said they broke one? God knows how.

So I considered fitting some magmotors to these gearboxes. Another option... Or rather the stronger 4 pole motor gearbox version. The mag motors rev higher... I still didnt work out if it would work well. Need to take a motor off and count.

But a simple bolt on solution like the motors you suggest or the groove motors would be simpler. Trouble is specs, drawings etc are too hard to get/compare!

[JoeC]

I have no idea of the efficiency of this motor, but it's probably decent- and with a 5:1 reduction would give you 8 mph gearing.

http://www.imperialelectric.com/product ... _frame.php

Part number P56SJ800. It weighs 21 pounds, and is rated for 33 amps continuous- just a hair less than the DX2 module is rated for. I'd much prefer one of those Agni motors for assured efficiency and torque, but this one likely costs half as much.

I realize that this, or any of the inline motors, is a big departure from what you've already accomplished. Sorry if it's an unhelpful direction.

[JoeC]

Thanks for the picture of the worm gears- it's interesting to see the guts. Another point to consider is that the higher the ratio, the less the wheel will be able to back-drive the worm gear, allowing regeneration. Forcefully turning the wheel may spin the motor, but not very well.

The magmotor might give you a bit of a boost over what you use now. If it doesn't suit you and you're gentle with it, you can likely resell it to a hobbyist for not much of a loss.

[Burgerman]

Problem is that to build a chair thats good indoors, (very compact and 25 inches wide x 40 ling inc footplate) and have a decent outdoor performance (70ah batteries and 6mph plus / fat 6 inch wide balloon tyres with good floatation) then I have to use the 90 degree type motors!

And I have a new drawing (beermat) that lets me fit two group 31 batteries in the same general design and style that keeps the exact same outline... That will allow 8mph to be practical! 110 ah minimum. But pancake or other non 90 motors wont fit...

http://www.odysseybatteries.com/battery/pc2150.htm

That should have the power true 8mph+ actually needs. Current chairs just dont cut it unless you are skinny or you buy a huge fat bounder...

And I can do it with my existing chair. Slight mod to increase battery tray length at the front by 110mm. And theres room for about 120...

I am going to finish up using mag motors, and home made 90 degree gearbox at this rate! It never ends. But I already have a better powerchair for most indoor/outdoor full time wheelies than you can actually buy by a country mile. This latest mod will just mean it does 8mph+ and still keeps same all day range and performance and can still go on the beach, in the van, home etc...

I like to make sure the big "mainstream" manufacturers are way behind and keep em looking silly! The other (lighter) better way is unaffordable lithiums...

But still dont know quite which motors/gearboxes etc to use. Prides hammer motors seem gutless in the extreme. Because they are trying to get all day range from a set of group 24 gels which cant even do the current required to get me up a steep ramp!

[Burgerman]

The advantage of the mag motors is that they rev hard. So no need for new gearboxes!

Gone to pub!
Back later. Or tomorrow.

[JoeC]

I would agree that you need the 90 degree boxes, except I think that you could work out a geometry with an offset spur gear or belt reduction that puts the motors right behind your knees, and have enough space to keep the batteries from sticking out the back. I haven't quite worked out how to do it without weighing a ton, but I have a couple of sales engineers getting back to me.

Regardless, I'll be eager to see what you can get out of the magmotors in comparison to the EMD motors. The neodymium is bound to be useful, and I'd be surprised if it wasn't at least a bit better.

[Burgerman]

Heres a question.

If very powerful extremely low impedance motors are used, compared to average 4 pole wheelchair motors does range deteriorate. If both are equally efficient?

Both are limited in current by the chosen controller at the low speed end anyway, and after that the low impedance ones should draw more current at any given speed. I think... Hence weedy 4 pole powerchair torque on 8mph chairs?

[JoeC]

This is a tricky question, and I'm still trying to figure it out and match it up with real-world measurements. The only way that they would be 'equally efficient' in our terms would be if they had the same range. I think that max current and no-load current are both strong indicators of how efficient the motor is. Those Agni motors have a no-load current of less than 2 amps, and can do 300 amps continuous.

Lets say you had two motors of the same peak efficiency, and one has a lot more output capacity than the other. If you look at that e-bike simulator I sent, all of the efficiency graphs for almost any motor or scenario you can dream up is shifted strongly toward high speed and low load. When a motor gets bogged down to half its no-load speed its efficiency takes a big drop. It is my understanding that the larger motor will spend more time near its "no load" condition, keeping efficiency higher. Pushing the throttle less causes less voltage to the motor, so it's still operating closer to its peak for that voltage.

Lowering the current limit also lowers efficiency, but it has the effect of flattening the maximum efficiency across a wide range of speeds, still peaking near top speed. Imposing no current limit tends to make the output graph look just like a manufacturer's spec sheet for the motor.

I think that the main thing to watch for when going to a larger motor (which I'm saying is likely to operate at a higher average efficiency even if they have the same peak efficiency) is that it does not have a larger no-load current. You'll never send less than the no-load current at full speed, so if you spend much time driving flat-out on concrete, this is likely to have a major impact on your range.

For comparison to the magmotor, I would say that you should take one of your four pole motors with no gearbox, hook it up to 24 volts, and measure the current while it's freely spinning. Compare that to the magmotor's no-load current. If the magmotor draws less current in this condition, I would strongly predict more range and better average efficiency out of the magmotor, even if they both have a quoted peak efficiency of 80%.

I can go home tonight and wedge some blocks under some powerchairs to see what they draw with the wheels spinning at full speed in the air. I haven't done that before, so it will be interesting to see what comes of it.

[Burgerman]

Report back! I will do the same with the 4 pole ones I use. Well almost the same. Loose motor/gearbox... Might need to be tomorrow, I dont know if I can lift the batteries...

And need to remove the electromag brake...

We could just be measuring how good / worn the bearings are though!

[JoeC]

We'll be measuring a little more than just the bearings- we'll also be measuring the effects of hysteresis in the iron core, eddy currents, resistance, drag from the brushes, and probably some other effects that I can't think of that contribute to the no-load current. Definitely need to remember to disengage the E-brake.

[JoeC]

Something else to bear in mind, moving to a larger controller and the small magmotors, will be motor temperature.

I was just reading this:

http://www.coolmagnetman.com/magstren.htm

And although neodymium will be far less prone to demagnetizing on the spot from a large current in the motor, it will be more susceptible to demagnetizing from being overheated.

I have a 7+ pound motor that I've measured at over 65C with the 80 amp DX module and a pair of Optima Yellowtops. I guess that's a long way off from the 150C temperature that would damage the magmotors, but their smaller size would make me want to pay some attention to their temperature during heavy use- especially with better batteries and a heavier load than my lovely wife.

Just thought that was interesting reading.

[JoeC]

I just measured the P200 with motors equivalent to the NPC-T74, and with both wheels completely off the ground and the throttle completely forward, the batteries were delivering a steady 13.5 amps. I was surprised it was so much! I was told by the NPC people that this motor (which they assured me was identical to the wheelchair version electrically) had a no-load current of 5 amps, compared to the 6.75 I was measuring.

Thinking for a moment, I realize that the E-brakes were drawing some current as well. A little more effort is required to insert my clamp meter to a point representing just the motor and not the brake. On further investigation, I found that a single motor was drawing 5.4 amps at full speed, which is in line with what I was told.

More chairs to be measured as I'm able.

[Foz]

i have had 1 of these chairs since they were released(just over 3 yrs) and i can say it is a great chair, that goes like stink. i have had Balder and F55s previously and can say it is btter than any of them. The motors have never failed and i am in it from 8am-10pm trekking everywhere. Another 8mph chair on market is Puma Alex, dont know anything about it.

[Burgerman]

foz, 2 or 4 pole f55? The old 2 pole ones were weak and very unreliable!

And which chair do you have now? You didnt say...

Ok I measured a free running motor (6 actually) and held the brake off manually.
They all measured more at first when "cold" up to about 10 amps...

After running for an hour (all of them at once connected to my battery bank and power supply in the garage) I tested them again.

All dropped to between 6.3 and 8.5. The lowest ones were new. Brushes not making full contact so limited "timing" I suppose. Even though tighter and harder to turn by hand.

The others were all about the same. 1 year old used motors tested on a pair of fresh batteries as shown in the photo. About average was a fraction under 7 amps. Not sure what this says though. Whats important is the difference in efficiency when doing x amount of work.

Of course it tells you that going flat out on a flat surface in a vacuum will use at LEAST 14 amps continually! Since it doesent take into account frictional, camber /c of g correction, etc etc... Probably much more than 14.

If it was 20 I would be surprised. Something to take into account. I am measuring 26v and pure dc. You are measuring 22v and pulsed duty cycle and your mneter may read peaks rather than average currents...

[Burgerman]

Added... Unbolting the gearbox makes no real difference (off load) to the amps.

[JoeC]

Very interesting, thanks!

For what it's worth, this is my hand held meter: http://www.newark.com/tenma/72-6185/dig ... dp/52F7511

I think I read once that it does half second averaging- which led me to use a different one when I was doing current measurements under heavy acceleration.

During my measurement I did not measure voltage at the motor input, but I do have my module programmed with "max motor volts" set to 30, and 100% speed is fully on. I guess I'm likely losing as much as a volt in my module and wiring at this current, but I'd be surprised if it was more.

When I was first starting getting serious about all this, I even hooked up the motor output to an oscilloscope to play around. I wasn't sure what to look for, but I have some friends and acquaintances who might. They said that the scope output looked like the motor controller was doing a good job of controlling things. This was the P&G 80 amp Pilot+,I was able to zoom in the time scale and make the "off" portion of the PWM essentially disappear; well over 99% duty cycle.

scope_20khz.jpg (84.23 KiB) Viewed 14120 times

[JoeC]

I also came across this application sheet the other day:

http://www.globe-motors.com/dc_motor.pdf

If you believe their equation, they say that a motor's peak efficiency occurs when it is drawing the square root of stall amps times no-load amps.

For my motor with 210 amps stall and 5.5 amps no-load, they'd predict that I'd see peak efficiency when I'm drawing 34 amps. Using the manufacturer's dynamometer data, the peak efficiency looks more like 26 amps. I don't know if I trust their data, because they don't give quite enough information on the test setup, and their PE of 86% isnt in line with the measured points on either side of it, and it seems a little too good to be true.

So, what's the point? Can I predict anything definitive yet? Not quite, but I feel like I'm learning something.

[Burgerman]

When at 100 percent full throttle straight ahead there is still a couple of "volts" spare plus/minus for steering. Or it would loose 50% steering power at full speed.

You can get full voltage to one motor at a time by turning away from it. (Joystick forwards and turning) But straight ahead measures about 22v here!

Motors are labled 22v as well for what thats means!

[JoeC]

AH! The reserve for steering? I can program for that with Dynamic. Normally it's set to something like 95% forward with a 5% reserve for turning, but she wanted full 100% speed in her "getting to practice on time" drive mode, so it's 100%, and slows down to turn.

My programming doesn't change the strong probability you're right about my system- there's really no other way to be sure, I'll have to measure actual volts soon. Might be a while, we're going to the gym tonight to do some kicks.

[Foz]

old 2 pole f55s. i have the groove with your ROHO cushion on! the wrong way round. 18 wide

[Burgerman]

foz, old 2 pole motors are terrible! And I am amazed you still have them working.

You need a set of 4 pole ones on there. And I have a set. Theres a few here...

Incidentally your programming is set to 35 or 40 compensation. If you up it to 115 to 120 it actually moves and turns! The manufacturers got it wrong from the start and couldnt change it after some certification bull... That works great with the 4 poles that actually need 40 to 50. And the 100 amp module just swaps in.

And you really should get the hacksaw out and build one like mine! Pleased the cusions working well!

As for learning something I think there are so many variables here that we just need to best guess and test!

How are the 8mph motors used in anger on the groove? Is it programmed to the max? And if not why not! I am going to order a set. Once I find out the motor case diameter.

[Burgerman]

Added... JoeC Have you ever ectually measured the true rms voltage (not peak) at the motors during stall conditions? Losing 6 or more volts from battery resistance, cables, connectors, wiring, controller etc isnt at all unusual. And battery voltage dropping low enough to trip the protection (reduces amps) is very common on all but new good optima or odyssey batteries.

I am about to replace all my battery cables and motor cables with bigger shorter ones with less connectors if any other than battery ones.

What we really need is 48 or much higher voltages.

[JoeC]

No, I haven't measured voltage at stall- but I did measure it under hard acceleration with an old pair of MK gels. It was dropping enough that protection kicked in, and current was scaled back. I know that the Optimas are holding up well enough to do better than this, but I'm sure it's a close thing.

You've got me wanting to go measure it now. And now that I'm thinking about it, I think I need to change out my wires for thicker ones. I used a chart for wire resistance, http://www.powerstream.com/Wire_Size.htm , and found that if I replaced the 14 gauge leads with 8 gauge, I could get a whole extra volt at the motor at peak output, and my simulators say that's and extra 2.5% acceleration for free. Likewise, rebuilding the battery cables might get me another large fraction of a volt- although those are already much thicker than the motor leads.

[Burgerman]

But longer.

That chart is useful. I think at least as much is lost at every junction and terminal too though. My cables smell of burning when doing 5 second stall tests! So there must be room for improvements in power here!

Did you do a volt drop test at stall yet? At various places along the route. Its very enlightening... You can then use mr Ohm to work out the real motor / controller/ cable / battery resistance and see where the power gets wasted most.

Back to 8mph groove motors... Can anyone measure motor case diameter please?

[JoeC]

Another piece of information: I just measured the no-load current of the S646SE with 80 amp P&G Pilot+ controller, 7 mph gearing, 13 inch wheels, no measurement of actual input voltage but the chair got a full charge last night. I measured just below 11.0 amps full draw from the batteries. This is less than I thought, as I've seen people using this configuration drain the batteries unusually quickly. This chair uses Electrocraft four-pole motors.

It wasn't convenient for me to measure a single motor without the E-brake, but even with the extra current included it drew less than the P200 motors, which have demonstrated superior battery life in sport use.

I haven't been able to find any more information on the Groove motor, but it is interesting to look at its spare parts page:

http://www.quickie-wheelchairs.com/whee ... og-release

It actually has an option for an encoder! I haven't heard anything good about the Delphi electronics that Sunrise/Quickie has been moving to, but if they are using encoders, that catches my attention.

[Burgerman]

I saw that too. Its used for miles traveled mostly, and possibly for keeping straight when their chair is so nose heavy it heads for the gutter when traveling along the road. If they are bright enough! I have another method...

11 amps is less than mine at 5.5 per motor. Including brake. Which puts me off as I expect them to be less powerful now! What do you recon? Mine were about 20 percent higher free running.

I still need a motor diameter! Need to know if my 145 tyre (measures 6 inches) and the motor casing will fit and not make my chair wider!

As far as keeping straight is concerned A better solution is to just fit a heading lock solid state heli gyro. My helicopter will fly flat out backwards with one fitted (not by me!) and stay rock solid on course without weathervaning around. And that is almost impossible! They really are that good! Ebay...

That rc interface had one in. I used it not for steering stability but on pitch axis (forwards / back) to try and make the chair wheelie in stable fashion "hands off" so to speak. Which kind of works. Sort of! A la ibot... But it runs out of speed to correct itself and then rushes along flat out trying to pick up the front or rear. Lack of motor power...