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Linix

Postby Burgerman » 13 Feb 2018, 16:23

Now. Everyone complains about sunrise ditching the AMT motors and using the chinese built Linix motors but they are good.

I just measured them rolling along a carpeted room at about 1.5mph at: 10.2 and 9.1 Amps each. Sounds a lot? That was of course motor amps. Battery amps was 4.1A total. At about 25% max speed.

This means that these are extremely low impedance motors so should be very efficient. If we do the math, thats about 19A drawn by two motors. And just 4A at the battery.

Lets say we can get only 50Ah from the 80Ah batteries. Thats 50Ah div by 4.1A or 12.2 hours at 1.5 mph. or 18.2 miles on carpet... Takes far less on concrete.
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Re: Linix

Postby expresso » 13 Feb 2018, 21:09

i think they are good also - smaller in size but seems to handle it and feels solid overall - i have about 2000 miles so far - this summer is going to be my third summer - meanwhile the older sunrise motors on my P222se - had to be replaced after 3 years i believe and i didnt do half as much with that chair as i did with this lithium chair once i did the battery - i was using it each day 30 - 40 miles for months first summer - i worn out the grey tires in a few months :)
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Re: Linix

Postby ICEUK » 13 Feb 2018, 23:20

I found them loud, sounds like a tram and they suck the ass out of my batteries that were replaced at same time.
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Re: Linix

Postby expresso » 13 Feb 2018, 23:28

yes thats true - they are louder than the previous motors - i got used to it i guess - - as for battery life with them - hard to say - i didnt feel they were any worse with lead before i went to lithium - depends on the lead battery i guess - mines where MK Gel 24 - brand new - used one summer - then went lithium
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Re: Linix

Postby Burgerman » 14 Feb 2018, 06:26

I know for a measured fact that they draw less battery amps and are lower impedance than the motors they replace by around 10 percent. By comparing both motor/battery amps as a fraction at stall, on both, (50A current is at a 10% lower motor voltage on linix) and by measuring actual battery amps as I drive at 1.5mph (25% speed) down my hallway with old/new.

If you get less range with these then look at your battery for the issue not the motors. Build quality? Remains unknown. But the sunrise rep told me they started using linix because they have the lowest warranty failure rate in the industry at under 1%. So if you believe her, then all good! On the other hand...
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Re: Linix

Postby hank » 14 Feb 2018, 10:25

Build quality? Remains unknown. ;)
Give you a few months running on the Linux motors john
tried and tested for your honest report on noise and quality :thumbup:
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Re: Linix

Postby Burgerman » 14 Feb 2018, 10:44

Sofar, electrically and efficiency is good. Measured. But noisier than AMT motors, but not bad at least these as they are new. But I never heard an old one thats as loud as say the EMD motors were. It all depends what you are used to. What will fail, as always, is the daft rubber cush drives... That I presume are in there.
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Re: Linix

Postby hank » 14 Feb 2018, 11:03

John
What i have found with the AMT ones they all use cheap metal shield
type bearings so run dry quick. :thumbdown:
Upgraded with SS quality rubber sealed ones.
On the gearboxes replaced the same but left the seal off one side
replaced with some quality swivel grease with a little ep 90 gear oil
mixed in which allows grease to get to now open bearings.
Lovely and quiet now. :thumbup:
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Re: Linix

Postby Burgerman » 14 Feb 2018, 11:37

The reason the motor manufacturers all use the shielded non sealed ones is that they can be oiled on assembly, and they then spin freely compared to rubber sealed grease filled ones. That improves motor efficiency, and when a company compares specs they sell on efficiency/price. So you might gain a couple of %. But they run dry soon enough, and get contaminated with carbon dust. So wear out faster. As an end user, you would of course prefer the rubber sealed greased for life ones to be in there as reliability means more than an extra couple of percent range. Same applies to casters on many chairs too.

As for gearboxes, you can buy semi fluid grease. Or top up with a little oil as you have. But here they are worries about warranty due to some leaking and so motors returned. So they use thick sticky greases.
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Re: Linix

Postby hank » 14 Feb 2018, 11:47

I understand with new ones on warranty issues :thumbup:
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Re: Linix

Postby dewaj » 28 Aug 2018, 05:12

Hi,

Is anyone aware of problems when these Linix 4-pole motors are hot?

My chair will often suddenly swerve right (downslope) when going across a slope and overreacts to joystick movements to correct. This only happens when the motors are hot, after running for a couple miles or so. The controller, a VR2, gets warm but not hot.

And does anyone know of a datasheet or some more technical tech specs for this motor?

Thanks...
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Re: Linix

Postby Burgerman » 28 Aug 2018, 05:34

Its not caused by hot motors.

My chair will often suddenly swerve right (downslope) when going across a slope and overreacts to joystick movements to correct.


Not sure what you describe unless you mean it will suddenly go towards the edge of a curb when traveling along a pavement or road edge. A transverse slope? On a rear drive chair its worse and this happens when the controller (the part of the VR2 that lives under the seat or on the base) reaches a temperature that causes the power module to reduce maximum power. (Amps). Running along a flat surface takes just a few amps maybe 10 to 12. Running along a transverse slope on a typical nose heavy rear drive chair takes a huge amount of power to stop it heading for the low side. This heats up the controller. Which then reduces power, that was needed to keep travelling straight.

This only happens when the motors are hot, after running for a couple miles or so. The controller, a VR2, gets warm but not hot.

Its not the motors, but the power module. The motors have no heat sensors. The power module has, and it rolls back power if the load is too high and as it warms up. In addition you likely have the usual programming problems that almost all powerchairs have. So that your steer control is hugely delayed, and when you try to stop it reacting, the same problem. It keeps on trying to turn, long after you tried to stop it. So it over-controls

Reprogramming it so that: turn acceleration, and turn deceleration are set to 100. And minimum turn acceleration, and minimum turn deceleration also both set to 100 fix that. At this point it will steer when told. And will stop turning when told. Instantly, instead of 2 seconds late.

The only way to stop the rollback of power (torque, and control) is to move the seat back as far as possible, which on a rear drive chair means also fitting a small centre foorplate. That means much less power (Amps) is required to steer, or to prevent the chair heading down the slope towards the low side. So that the power module doesent heat up as much. Other fixes include, setting the rollback temperature higher in programming if it allows that, and addig a fan to the power module. And adding using a more powerful controller like the 120A r-net. Also 4 pole motors are less likely to induce rollback than 2 pole motors as they take less watts or battery amps, for the same level of torque.
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Re: Linix

Postby rover220 » 28 Aug 2018, 05:34

they are decent motors, otto bock have also started using them on the new juvo range.

the brakes are a weak point, have replaced several but they are only relatively cheap and half hour job to do.
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Re: Linix

Postby dewaj » 28 Aug 2018, 06:31

This is a Quickie Pulse 6B centre drive.

I've just swapped out the Interstate AGM batteries for a new pair of MK's. One of the Interstate's has gone bad though it's just a few months old.

Since the motors use permanent magnets and permanent magnets get weaker as they heat up, I do suspect the motors first. It's possible they also may be mismatched? Rumour is that Sunrise tries to match motors as closely as possible. Or perhaps that's just marketing propaganda.

The motors do get pretty hot after a while especially when running at full speed for a couple miles or so, especially in summer. The controller is 70A, if I understand correctly from the exquisitely poor info I've been able to glean so far. I'm pretty sure the configuration is plain-old stock/default. Until I get the programmer that I want I'm only guessing here.

Oddly, this never occurs when crossing the slope in the other direction. Only when the right side is lower. And only when the motors are hot. The slope is about 15 degrees. On more or less level ground, or up and down slopes, it doesn't veer either way.

Thanks for the reply!
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Re: Linix

Postby dewaj » 28 Aug 2018, 06:43

Burgerman wrote:Its not the motors, but the power module. The motors have no heat sensors. The power module has, and it rolls back power if the load is too high and as it warms up.


By the way, I noticed that the controller power FETs have no heatsink. They are pressed against the PC board completely dry (and clean!). Nothing else to dissipate heat at all. So even forced air cooling isn't very effective. Unfortunately it's difficult to even guess how hot the transistors get.

Would it be normal to fold back current on one channel only? That seems like a potentially dangerous thing to do. Such behaviour could have me flipping into a ditch, and wind up under the chair.
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Re: Linix

Postby Burgerman » 28 Aug 2018, 07:22

I've just swapped out the Interstate AGM batteries for a new pair of MK's. One of the Interstate's has gone bad though it's just a few months old.

Theres a surprise. Interstate are junk.

Since the motors use permanent magnets and permanent magnets get weaker as they heat up, I do suspect the motors first. It's possible they also may be mismatched? Rumour is that Sunrise tries to match motors as closely as possible. Or perhaps that's just marketing propaganda.

Marketing? Yes. Mismatched? It would be hard to tell, and it would be constant.
Magnets in a motor are bonded to the case and are at the same temperature as the case. If it takes your skin off, that may be hot enough to demagnatise them slightly long term. But it doesent come and go.
And the magnets used are designed to get hot, at very least warm, and last many years. The rest of the motor dies first. In fact magnets that do get weak due to heat do that permenantly. The main thing that demagnetises magnets is high magnetic flux in the opposite direction. And even with a 120AMP controller that doesent happen. So its 99.9% certain that its got nothing to do with magnets or motor heat. And as your controller is only 70A so thats never going to happen. My own chair is programmed to go. And uses a 120A controller. And is rear drive which gives much more motor loading much of the time. And its double the weight of your own chair, and I am 20 stone! And my motors are identical. And they dont get hot enough to matter.

The motors do get pretty hot after a while especially when running at full speed for a couple miles or so, especially in summer. The controller is 70A, if I understand correctly from the exquisitely poor info I've been able to glean so far. I'm pretty sure the configuration is plain-old stock/default. Until I get the programmer that I want I'm only guessing here.

Correct and it doesent go or steer properly like the vast majority of powerchairs. And 70 isnt enough...

Oddly, this never occurs when crossing the slope in the other direction. Only when the right side is lower. And only when the motors are hot. The slope is about 15 degrees. On more or less level ground, or up and down slopes, it doesn't veer either way.

That must be coincidence? Cant think of any other thing that could cause that.
This is 15 degrees. An official 4x4 off road ramp designed for testing suspension articulation in competitions. Steeper than you think!

Image

Other possibility.
Worn or stuck motor brush. But unless its old and recently started doing this then thats unlikely.
Also a 70A controller is pretty weak. So if it rolls back by say 25% that doesent leave enough for control, made worse (much worse) by programming.
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Re: Linix

Postby LROBBINS » 28 Aug 2018, 07:52

Another possibility is that the clearance of the disc of the solenoid brake on one motor is off and that when the motor heats up it grabs. Some brakes have clearance adjustment screws. If so, you can use a feeler gauge to see how they're set, make sure they are parallel to the pressure plate and set the same on both brakes. The adjustments are VERY small - a few thousandths too tight or too loose and they won't work properly. Someone on this board also recently reported motor problems that were cured by carefully cleaning the brake.
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Re: Linix

Postby Burgerman » 28 Aug 2018, 11:54

And these must be set correctly... If any are set a little low, esp temperature or current foldback level, and time, you will get the problems you are having. Further disguised by delayed steer settings shown above. It doesent explain why its one motor.

PAY particular attention to the settings in red. This is a TIMED current foldback, and a TEMP foldback. These can both operate separately and start reducing power when you dont want it...

CURRENT LIMIT MAX., CURRENT LIMIT MIN., CURRENT FOLDBACK - THRESHOLD, TIME, LEVEL, & TEMPERATURE BOOST CURRENT & TIME
These parameters affect the VR2’s current output with relationships to time and internal VR2 temperature.
The parameters associated with the Motors are:

Current Limit Max.
This is the current the VR2 can deliver until the programmed value of Current Foldback Temperature is reached.
Programmable between 20A and the Control System’s Maximum in steps of 1 Amp

Current Limit Min.
This is the current the VR2 will deliver at 80°C internal temperature.
Programmable between 20 and Current Limit Max in steps of 1 Amp


Current Foldback Threshold
This parameter sets the level of current which when exceeded activates the Current Foldback Time parameter.
Programmable between 20 and the Current Limit Max in steps of 1 Amp


Current Foldback Time
This parameter sets the maximum time the control system can be at its current Foldback Threshold before the control system begins to reduce the available current.
Programmable between 0 and 250 in steps of 1 Second


Current Foldback Level
This parameter sets the percentage of current foldback when the control system is at the Current Foldback Threshold for a period greater than current Foldback Time. The value is a percentage of the programmed Current Limit Max.
Programmable between 25 and 100 in steps of 1%.


Boost Drive Current
This is the current the VR2 can deliver for the period of time set by Boost Drive Time.
Programmable between 20A and the control system’s maximum in steps of 1 Amp.

Boost Drive Time
This is the length of time that the VR2 can deliver the Boost Drive Current for.
Programmable between 0 and 10 in steps of 1 Second.

Current Foldback Temp.
This parameter sets the temperature within the control system at which the current starts to reduce linearly.
Programmable between 25 and 70 in steps of 1 Degrees C

It is important that the maximum values stated in the table VR2 Current Management are not exceeded.

Example 1- Time / Threshold / Level:
The parameters Threshold, Time and Level can be used to protect the motors from overheating. If the motor current exceeds the value set by Threshold for a period set by Time, then the VR2’s current output will be reduced to a value set by Level.
After a fixed reset period of 5 x Current Foldback Time, the current output will be allowed to return to the full current, if demanded.
Settings: VR2 is programmed to:
Current Limit Max. = 60 Amps
Current Foldback Threshold = 60 Amps
Current Foldback Time = 15 Seconds
Current Foldback Level = 25%
This is useful for protecting motors against potential damage when the wheelchair is being used on a long gradient. After 15 seconds the current output of the VR2 will reduce to 25% of 60A = 15A. After 5 x 15s = 75s, the current output will return to 60A.


If no timed foldback is required, simply set Current Foldback Level to 100%.

Example 2 - Temperature:
The VR2 protects itself by measuring its internal temperature. When this temperature reaches a certain level the current output starts to reduce. This relationship is shown in the following illustration.
1 - Current Foldback Threshold.
This is the current the VR2 can deliver until the programmed value of Current Foldback Temperature is reached.
2- Current Limit Min.
This is the current the VR2 will deliver at 80°C internal temperature.
3 - Current Foldback Temp.
This parameter sets the temperature within the control system at which the current starts to reduce linearly.
It is important that the maximum values in the table shown below are not exceeded for the VR2 model you are working with.
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Re: Linix

Postby dewaj » 29 Aug 2018, 07:18

Burgerman wrote:Theres a surprise. Interstate are junk.


Oh, But Wait! There's More!

I shifted the Interstate batteries and caught a good whiff of sulfuric in the process. The batteries were pretty much all alone in a corner since the swap. I've never smelled sulfuric vapour coming from a battery that wasn't leaking, contaminated or hot before. No leaks were found. It's not a good sign at all. Perhaps I should have invested in an acid spill kit after all.

Burgerman wrote:Magnets in a motor are bonded to the case and are at the same temperature as the case. If it takes your skin off, that may be hot enough to demagnatise them slightly long term. But it doesent come and go.
And the magnets used are designed to get hot, at very least warm, and last many years. The rest of the motor dies first. In fact magnets that do get weak due to heat do that permenantly. The main thing that demagnetises magnets is high magnetic flux in the opposite direction. And even with a 120AMP controller that doesent happen. So its 99.9% certain that its got nothing to do with magnets or motor heat. And as your controller is only 70A so thats never going to happen. My own chair is programmed to go. And uses a 120A controller. And is rear drive which gives much more motor loading much of the time. And its double the weight of your own chair, and I am 20 stone! And my motors are identical. And they dont get hot enough to matter.


That's useful info. I don't really have experience with DC motors this big.

Burgerman wrote:This is 15 degrees. An official 4x4 off road ramp designed for testing suspension articulation in competitions. Steeper than you think!

Image


That's about right. The road has a high crown and seems more like a flat ellipse than circular. The shoulder starts getting quite a bit steeper at the fog line.

The chair didn't swerve today. I was going a bit slower so that may have helped.
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Re: Linix

Postby dewaj » 29 Aug 2018, 07:25

LROBBINS wrote:Another possibility is that the clearance of the disc of the solenoid brake on one motor is off and that when the motor heats up it grabs.


Thye may well be out of adjustment. When I let go of the stick going down a slope the chair sometimes keeps going for a bit after the brakes are set. It was my understanding that the brake would not be set while the motor was still turning. I can't get the wheels to turn by pushing it after it stops, though.
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Re: Linix

Postby dewaj » 29 Aug 2018, 07:53

Burgerman wrote:And these must be set correctly... If any are set a little low, esp temperature or current foldback level, and time, you will get the problems you are having. Further disguised by delayed steer settings shown above.


It responds instantly when stopping. There's no delay when I let go of the stick or when I stop hard by pulling the stick back. It does delay too long and accelerate too much when turning slowly and it tends to respond very slowly and then kick too hard and move too quickly when slowly accelerating up a slope at the lowest speed settings.

I've copied what you posted above for when I get to adjust the programming. Thanks for that.

I am completely unfamiliar with this system and want to learn all I can and understand it before messing about. I don't know how delicate it may be or how upset it may get when something changes. I haven't found where anyone has done any kind of data collection, except programming and observations about operations. I think I should go about doing some hard data collection/logging and learn better how it works. So I guess there's a Project afoot, now.
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Re: Linix

Postby dewaj » 29 Aug 2018, 07:58

Burgerman wrote:I just measured them rolling along a carpeted room at about 1.5mph at: 10.2 and 9.1 Amps each. Sounds a lot? That was of course motor amps. Battery amps was 4.1A total. At about 25% max speed.


What did you use to measure the current? Analog meter?
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Re: Linix

Postby Burgerman » 29 Aug 2018, 09:20

There are many ways to measure current.

1. Clamp meter. As I used here to measure Amps to show why a 50 to 80A power module just isnt adequate, by extending 1 motor cable to my knee: http://www.wheelchairdriver.com/gopro/motoramps.mp4

2. Or with the R-Net control system, (and some others) you can open a screen in the OEM software on a laptop on your knee, and read real time data directly. With a 6mph motor it hits 120A all the time.

L.Motor Amps
R.Motor Amps
L.Motor Volts
R.Motor Volts
Battery Amps L and R
Battery Volts L and R
And more, as you drive.
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Re: Linix

Postby dewaj » 29 Aug 2018, 19:39

Interesting video!

Which model meter was used?
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Re: Linix

Postby Burgerman » 29 Aug 2018, 19:54

Dont remember what its called... I have a few. All are true RMS though.

You can see instantanious voltage drop too. This below, is a slightly expensive fluke test meter measuring battery volts at high frequency and logging the result. Fluke 289 http://www.test4less.co.uk/media/catalo ... -289-2.jpg

Its got real time volts on top - big numbers 25.4 or imilar.
Its also showing the peak volts under that as three lines.

Peak high
Averaged
Peak low. Drops to 18.94V instantly.

Watch the peak low volts drop from 25.25? to 18.94 volts with one tiny wheelie. Imagine what a hill does... Showing why lead batteries are so crap... Crappy vid, old chair, but run at full screen allows you to see.

http://www.wheelchairdriver.com/gopro/voltdrop.mp4
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