Does a rolling magnet gather no mess?

Does a rolling magnet gather no mess?

Sad, but I woke up with this question in my head...

If the model 3 has perminate magnets will they gather iron dust from the road? Other cars will leave break dust. Will this gather on the Model 3 magnets and cause wear or other issues? I am a fan, not trying to cause any short sell. I just dont know the practical issues of a magnet over 10 years.

Coastal Cruiser. | 21. Oktober 2017

No, a rolling magnet only gathers mass.

At least i think so. If you are referring to the permanent magnets on the motor... the magnets are attached to the rotor, deep inside the motor, surrounded by the metal stator and motor frame. Although I did not design or build the motor, it seems a fair guess that the environment inside the motor is a sealed one.


carlk | 21. Oktober 2017

Motors are shielded well there will not be any significant magnetic flux outside the motor.

RedShift | 21. Oktober 2017

If there was no dust shielding, dust would start affecting the bearings leading to early wear on the bearings and failure. Same thing applies to the pistons and cylinders in an ICE.

RedShift | 21. Oktober 2017

Sorry, not just shielded but sealed against dust intrusion.

topher | 22. Oktober 2017

What happens to the permanent magnets in the electric motor in you ICE vehicle?

Thank you kindly.

dave.m.mcdonough | 23. Oktober 2017

It's a sealed environment, and 99% sure it's also entirely filled with lubricant. This is like worrying about brake dust getting into your transmission.

WantMY | 23. Oktober 2017

Tesla main drive motors are induction 3-phase AC type electric motors, so no magnets are used. The rest of the motors are similar what is being used in ICE vehicles. There is no giant magnets riding alone in Teslas.

Frank99 | 23. Oktober 2017

Also, the motor is designed to focus as much of the magnetic field as possible inside the motor, so the permanent magnets will only create a weak field outside the motor. You might get a small amount of iron dust on the outside of the motor, but that's about it.

Garyeop | 23. Oktober 2017

Nice to hear the motor is sealed. My non engineer minds eye assumed the motor was on the wheel. I now understand there is a motor and a transmission. It gives me a reason to research the power train. Espececially since it goes 1 million miles between servicing. :)

WantMY | 23. Oktober 2017

There is no transmission in Teslas, but they have very simple 2- stage reduction gear box (~10:1 ratio) with integrated differential (like in any other ICE car) and cooling. Not sure about 1 million miles intervals, but many used Teslas offered for sale have pretty big milage on them. In fact, I would not even consider buying ICE car with those milages, especially European ones.

PBEndo | 23. Oktober 2017

Does a Rolling Magnet Gather no Gauss?

Yodrak. | 23. Oktober 2017

Interesting. Does the motor turn in the opposite direction when the car is in reverse?

"There is no transmission in Teslas"

dave.m.mcdonough | 23. Oktober 2017

@WantT3 It's rumored that the motor in the 3 has magnets, probably an induction hybrid of some type. Not the same motor as the S.

WantMY | 23. Oktober 2017

@Yodrak Yes, it turns in opposite direction because inverter change phase sequence to turn the direction it suppose to.
@dave.m.mcdonough there is no way Tesla will be using permanent magnets as it makes motors for model 3 more expensive and permanent magnets tend to demagnetize and go kaboom over time. All modern EV are using ac motors for this very reasons: low cost and no degradation over time.

WantMY | 23. Oktober 2017

The only fancy feature in the S/X motor is active rotor cooling to increase performance. It is possible model 3 may not have it, but 5.1-5.6 0-60m/h is good enough for many folks.

WantMY | 23. Oktober 2017

Telsla also limits speed to 15m/h in reverse, so there is no way to race in reverse ;-)

Yodrak. | 23. Oktober 2017

I guess that depends on how you define a transmission. Teslas do have a device with a gear (or gears) that establish a different rotational speed for the wheels than that of the motor. Far simpler than a multi-ratio transmission for an ICE vehicle, but never-the-less a device that has the wheels turning at a different speed than the motor. (I apologize for the redundancy.)

Frank99 | 23. Oktober 2017

It's a point of controversy, that Model 3 reservations holders with nothing else to talk about chew on endlessly. There are documents filed with the EPA that indicate a permanent magnet motor; there are others who believe (without even a document) that Tesla wouldn't move away from Induction motors.

Me? I don't much care; I just want my car. The performance of the car is perfectly adequate for my needs, whether the motor has permanent magnets or not. I figure if Tesla had a reason to change from Induction motors to more expensive, harder to build, permanent magnet motors with an iffy supply chain, there must have been a very good reason. But it doesn't matter - the performance and efficiency is top-notch, so I'm happy with whatever path they chose.

dave.m.mcdonough | 24. Oktober 2017

Well, as detailed in some of those articles Xero linked, a hybrid design containing magnets does have some advantages. I'm ok with this. And no, they aren't a ticking time bomb like T3 would have you think.

WantMY | 24. Oktober 2017

@xerogas Thanks for the links! The moment I realized Tesla 3 is using PMAC motor, I was tempted to cancel my reservation, but reading further indicates that PMAC is only used in Tesla 3 LR model. Standard Range Tesla 3 is using same proven induction motors like in S and X. So that settles my choice - Standard Range Tesla 3.

BTW, here is quote about shortcomings of PMAC, yes the type of motor Tesla spent a decade badmouthing:

"Finally, high current or operating temperatures can cause the magnets
in PMAC motors to lose their magnetic properties. Permanent magnets,
once demagnetized, cannot recover, even if current or temperature
returns to normal levels. PM drives reduce the risk of high-current
demagnetization with over-current protection. Some motor designs
further minimize the possibility of demagnetization with
high-temperature magnets, integrated thermostats, and restricted motor
operating temperature."

andy.connor.e | 24. Oktober 2017

Does a rolling golem gather no rust?

WantMY | 24. Oktober 2017

@Yodrak Gear-box is the term Tesla is using when referring to this thing. Maybe because of the motor is directly connected to the drive train and its rotor is integral part of the first gear pair. It is always connected, there is no neutral.

dave.m.mcdonough | 24. Oktober 2017

I'm calling BS on you kneejerking so hard over the motor having magnets that you cancel order. Don't overheat the thing and you'll be fine. It's not like they added brushes.

topher | 24. Oktober 2017

"there is no neutral."

Before someone screams "SAFETY HAZARD", there is a neutral. It is achieved by not putting any power to the motor, and no load (so no regen). There is no neutral gear setting.

Thank you kindly

ReD eXiLe ms us | 24. Oktober 2017

Photos of the Monroney sticker on a blue Model 3 at the July 28, 2017 Handover Event confirm it uses a permanent magnet AC motor of some type.

andy.connor.e | 25. Oktober 2017

Ask yourself if anything you've ever used that had an electric motor, ever had a problem such as what is being asked here. Then you'll come to the realization, that this was generated because people are scared to death of a technology that they dont understand.

"People fear what they do not understand"

psusi | 26. Oktober 2017

Huh? Tesla uses induction motors.

Frank99 | 27. Oktober 2017

psusi -
Tesla documents indicate that the Model 3 is using a Permanent Magnet motor in the Model 3, not an Induction motor. Quite a surprise to me also.

Yodrak. | 27. Oktober 2017

Clothes dryers. They use open motors that are really good at capturing whatever lint the filter and exhaust pipe miss. Not a motor design that would be used in an EV, but you did ask about "anything ... that had an electric motor".

"Ask yourself if anything you've ever used that had an electric motor, ever had a problem such as what is being asked here."

Frank99 | 27. Oktober 2017

RC Cars - especially cheap RC cars. Drive'em around the dirt out back, and you'll find a nice collection of iron dust in/on the motor.

ReD eXiLe ms us | 27. Oktober 2017

On YouTube FullyChargedShow recently showed EV components that Bosch is marketing to traditional automobile manufacturers. The motors all seemed to be of an open, vented design.

[ YouTube -- 4k5TDZ6irG4 ]

Frank99: I believe that such R/CD do not use brush less motors. The metallic 'dust' is shavings from the mechanism itself.