Help needed with scooter motor

[mistercrash]

It's a 500w 48V scooter hub motor. It's running on 74V30Ah Konion battery. It's sealed and liquid cooled with synthetic ATF. The motor has 6700 km on it, I just fixed it with new hall sensors and bearings. It ran great for a week and all of a sudden, it has no torque. Very sluggish off the line. When I put the front wheel of the scooter against a wall and twist the throttle, I get a sound like the motor is turning but the wheel isn't moving I don't get this one, can someone help me diagnose this so that I can fix it?

Here's a little clip to show what it's doing.

http://youtu.be/APVDTRSZ2pc

Thanks
Ray

 

[ian.mich]

It's a 500w 48V scooter hub motor. It's running on 74V30Ah Konion battery. It's sealed and liquid cooled with synthetic ATF. The motor has 6700 km on it, I just fixed it with new hall sensors and bearings. It ran great for a week and all of a sudden, it has no torque. Very sluggish off the line. When I put the front wheel of the scooter against a wall and twist the throttle, I get a sound like the motor is turning but the wheel isn't moving I don't get this one, can someone help me diagnose this so that I can fix it?

Here's a little clip to show what it's doing.

http://youtu.be/APVDTRSZ2pc

Thanks
Ray

Have you used the lyen tester on halls and phases? tried a different controller? first couple steps in diagnostic.

 

[mistercrash]

It's a little hard for me to do that, I don't have a Lyen tester or an extra controller.

 

[major]

When I put the front wheel of the scooter against a wall and twist the throttle, I get a sound like the motor is turning but the wheel isn't moving I don't get this one, can someone help me diagnose this so that I can fix it?

Sounds like the rotor is slipping on the shaft; rotor rotates; shaft does not.

 

[mistercrash]

Does anyone know what this problem is? Anyone ever got the same thing happening to their motor and can tell me what is causing this?

Thanks
Ray

 

[dogman dan]

It would seem that the axle is stripped, and the stator is rotating in there.

Is this a direct drive motor or a geared? A planetary gearmotor is unlikely on a scooter, but if so the clutch might just be broken.

One thing I don't understand is, if the stator is rotating inside there, why doesn't it wind the wires around the axle and break them all. I'm confused.

 

[mistercrash]

It's a direct drive motor and I thought the exact same thing about the wires. In my mind, the stator can't be turning inside the rotor for very long. I even checked if the ATF that dripped out of the motor for a while broke the seal between the tire and rim and maybe the whole rotor/rim assembly was spinning inside the tire but that's not it. I would have been very surprised a 500w motor could do that. I am very confused about this also and that is why I'm asking how to fix this. Is it really the motor or could it be the controller? I use an 18FET Lyen controller. I did a light shunt mod on it and built up the traces recently. Could I have damaged something by doing this? The controller has been working very well for a month since the mods, although I thought I could get a little more torque out of it, building up the traces and modding the shunt didn't change much.

In the meantime, I am still using the scooter to go to work, it's the only thing I have to get there. Starts from a stand still are slow and I try not to make the motor do that whinning noise too much. Once I get rolling, I can accelerate to the 60 km/h top speed. I don't even know if I'm causing more damage by using the scooter because I have no idea what the problem is.

Thanks
Ray

 

[major]

Can the rotor be slipping inside the rim?

 

[jpgey]

Hello, sorry for my English, i have almost the same noise with my cromotor if i lock the wheel with brake.
I thought i had blow the motor or twist phase wire, but no.

I think it is some controller protection against too much phase amps, or battery cannot deliver enought amps, i have to check with my setup.
I have also another idea, if the controller think the motor is lock (throttle up but no hall return) the controller might send anyway some phase current to unlock the motor, that could be the rotating sound we hear.

If i where you i would check my controller setup and battery state.

Hope it help,

 

[mistercrash]

You're English is very good. I'm French also, I just got lost in an English Province 10 years ago and never got out :lol: I will follow your lead on controller settings, battery state and I'll try to see if there's something wrong with my throttle and maybe check settings of my CA also. Anything is better than to open that motor again now that it's all sealed with ATF inside.

Something I noticed today, there's two ways of checking the speed I'm going on my scooter. One is a speedometer original to the scooter and works with a worm gear inside the front wheel. The second way is on my Cycle Analyst which gets its signal from the Lyen controller. When I twist the throttle from a dead stop, I get the whining noise from the motor and the scooter's speedometer will show a speed of 20 km/h while at the same time the CA shows a speed of 45 km/h. So the CA seems to get a signal from the controller that the motor is spinning at 45 km/h when in fact it is only going 20 km/h. Weird!!!!!

I really hope to find the problem.

Thanks
Ray

 

[mistercrash]

I went to the garage to check the battery. All the cells are good with good voltage and the total voltage of the battery stays above 74V even on start up at 4800 watts on the CA. So I don't think it's the battery. I unplugged the CA and the whining is still there on start up so I don't think it's the CA settings. That would leave the throttle or controller. I'm really starting to think that there's nothing wrong with the motor. What's wrong with this thing?! :|

 

[jpgey]

Can the rotor be slipping inside the rim?

Why not, If the magnets are glued in a rim that is herself crimp inside the wheel rim, perhaps we can imagine that Atf oil get introduced between the two circle ?
And then the magnet rim turn inside the wheel rim ?

 

[itchynackers]

That is what I was thinking. For some reason, the magnet ring is spinning/slipping in there. The fluid is keeping the rubbing metal from deteriorating (for now). Maybe the fluid ate away at the adhesive causing your issue. Seems like a motor tear-down is in order.

 

[mistercrash]

I tried ATF before and it did in fact dissolve the glue that held the magnets in place. To remedy this problem, I cleaned all magnets and reglued them using JB Weld. I assure you, the magnets are very firmly held in place.

The tubeless rim of this motor is welded to the rotor. The rim and rotor are one piece and the magnets are JB Welded. I am convinced that the problem isn't there (or I want to convince myself because I really don't want to open this motor now that it's sealed). I slept on it and went back to it this morning and I am still stumped.

 

[itchynackers]

I'm trying to think of a way to test if the magnets are spinning. Maybe someone with more electronics knowledge can help, but here is what I came up with.

Tap a multimeter into a pair of hall wires. If while the motor is making the noise (while the scooter is not moving), and the hall voltage is oscillating from 0 to 5 volts, wouldn't that mean the magnets are moving?

 

[mistercrash]

If the hall voltage is oscillating from 0 to 5 volts, wouldn't it mean that the stator is spinning and the halls are moving passed stationary magnets? Geez I'm going nuts trying to figure this out. I checked the settings of the controller with the laptop, change some things to see if it would make a difference but nothing worked. I still get the whining noise and no torque. I looked at the throttle twist grip and it seem to me that there's nothing wrong with it. So I'm going as a last resort to check some connections here and there and if that doesn't work then I will just have to open that motor and see if there's something wrong inside.

 

[mistercrash]

What a mess!!
I took the motor off the scooter and opened it and draining the ATF and letting the parts drip any excess on a rag. Makes a awful mess and I didn't want to do it but I had to. And the verdict is......

ATF eats a lot of stuff, like the other time I tried it, it made the heat shrink on the wire kind of soft and squishy. I don't think that's a good thing. ATF also ate the JB Weld and yes!... The magnets are now unglued from the rotor ring. The only thing holding them on it is their magnetism of course. After just a couple weeks of running, the ATF was quite dirty looking and there was a lot of little pieces of JB Weld floating around in the motor. That can't be good either.

So the theory of the magnets becoming unglued thanks to the ATF and all of them slipping on the rotor ring because the ATF offered some lubrication might be what really happened to this motor.

I took a spare motor that is the exact same thing but that is not liquid cooled with ATF and installed it on the scooter. Problem solved, the torque is back and no motor whining.

So what now? What is my option to run a 220 pound scooter with a 250 pound rider at a top speed of 60 km/h with tons of torque to go up steep hills? Drilling holes in the 500 watt motor didn't cool it enough. Liquid cooling with ATF did work only for a while until the ATF made a lot of damage to the inside of the motor. So here's the only option available, a 4 to 6 kw hub motor with a 10 inch tubeless rim? Yeah, that's what I'll have to buy.

Thanks everyone and I hope this can help someone else.

 

[Arlo1]

Bigmosse posted a link to locktight hysol made for gluing magnets and works well even when submersed in oil its basicly the best stuff on the market. I've used it a few times once was in hot oil. Works 100% the oil is not your cause of the issue the improper use of uh weld is. I think bigmoose posted it in the tech section but make sure you get the right stuff. I will find the link later if you cant

 

[major]

You could use a different coolant, perhaps water or antifreeze mix.

 

[Chalo]

I tried ATF before and it did in fact dissolve the glue that held the magnets in place.

And then you did it again. Impressive.

Why aren't all electric motors oil cooled? Are electrical engineers just a bunch of ignorant hacks with no imagination? Or do you think the people who develop these things for a living might have practical reasons not to do it?

 

[Arlo1]

I tried ATF before and it did in fact dissolve the glue that held the magnets in place.

And then you did it again. Impressive.

Why aren't all electric motors oil cooled? Are electrical engineers just a bunch of ignorant hacks with no imagination? Or do you think the people who develop these things for a living might have practical reasons not to do it?

Actually ATF is one of the best for cooling. Engineers simply don't use it because its not needed until the motor is really pushed hard and most engineers would rather make the motor a little bigger then oil cool it for simplicities sake.

 

[mistercrash]

Thanks arlo, very nice of you. I'll try to find that link.

I tried ATF before and it did in fact dissolve the glue that held the magnets in place.

And then you did it again. Impressive.

Why aren't all electric motors oil cooled? Are electrical engineers just a bunch of ignorant hacks with no imagination? Or do you think the people who develop these things for a living might have practical reasons not to do it?

Where the heck does this come from?

 

[itchynackers]

Don't mind him. He ridicules everyone for anything. Wouldn't you be mad at the world if you had to wear that stupid hat of his?

 

[Arlo1]

Here is the link I was thinking of.

I used the Hysol EA9394 I believe exactly if you lived closer I would help you re-glue them. But make sure you clean the magnets and the surface they attach to with a scuffing pad then a alcohol or something. I use brake clean because I buy it by the 5 gal container for my shop. This stuff is most likely better then you had on there form the factory. I would be the heat is what worked the magnets loose. Remember if the rim and the magnets have different expansion rates running the rim to hot will cause any glue to brake loose.

 

[dogman dan]

FWIW I have had the magnet ring rotating while the stator stayed stationary in a damaged motor.

But it was a different situation, a brushed motor. In my case the way the motor is built the magnets are on the part attached to the axle, and the winding rotates around that. A cheap press fit ring held the magnets and would enlarge enough when hot to slip.

I just didn't think it was possible for this to be happening in a brushless motor. Wouldn't the magnet ring get hot first, and expand to be tighter in the hoop of the rotor/spokes assembly? In the brushed motor, the hotter magnets would get looser, so they could slip. I stuck a screw in it to stop the slip.

I never thought about the glue dissolving. Once unglued, the magnets could run around in circles in there.

If you read close Chalo, he said the previous time the ATF dissolved some heat shrink, not that he had the oil melt the epoxy and loosen the magnets twice. Pretty different, so he's not so dumb.

Do some tests with other oils and and a good high temp epoxy, including the heating. Maybe you can find the right oil. You aren't lubricating, you are just using the oil to transfer heat. So try all kinds of oils. Maybe you just need olive oil or corn oil, rather than automotive oils loaded with chemical additives to do things you don't need.

Lastly, get bigger motors. I cook motors too, and every time it's because I'm doing motorcycle work with a bike motor. You can have your cake and eat it too, but only if you bake a big enough cake for the crowd that comes.