Tesla Electric Motor

Tesla Electric Motor

I am wondering if the design of the Tesla motor could be modified to double the torque and cut the operating rpm range by half. It eliminate the 2:1 fixed reduction gear that Model X uses. May be reduce the weight of the car, cut costs.

I have not been in this kind of think in decades, but I think it would involve increasing the diameter, doubling the elements in the squirrel cage? Or keep the same diameter, just double the squirrel cage?

Any experts in the house?

Runar | 7 March, 2013

Certainly, i think fisker karma has something like this. Higher torque at lower rpm. The question is, does this improve actual performance?

Timo | 7 March, 2013

Reduction gear is 9.73:1. With 14k RPM you would be going over mach one without it. Motor doesn't weight much, something like 70lbs, which is really insignificant, and it is (relatively) cheap part. I think Tesla knows what it is doing, it has some of the most brilliant engineers in it's payroll.

Brian H | 8 March, 2013

Bubba, the reduction gear is about 9.7:1. Where did you get that nonsense? A TM motor spins at up to 14,000 rpm. An axle and tire spinning that fast with a 2:1 reduction gear would make the car move about 1200 ft/sec, or just over 750 mph., or Mach 1.

Timo | 8 March, 2013

...going supersonic.

Cattledog | 8 March, 2013

So then the lineup would be:

Model S 40
Model S 60
Model S 85
Model S P85
Model S SSP85? 0-60 in .44 seconds?

dortor | 8 March, 2013

Motor with the induction unit weighs over 300 lbs - according to the factory tour I took on tuesday.

Timo | 8 March, 2013


That's entire module with casing, cooling, PEM, connections, reduction gear, bearings etc. Motor alone is much lighter, though it could be that it was 70 kg instead of lbs now that I think of it.

Anyway, it's light. Think of hub-motors, four of those give same power and they are light enough that you can put them inside the wheel. Electric motors are really powerful for their size. It's the battery that weights a lot but even that is just about 1000lbs casing and all, about 3300 lbs of Model S is other things than drivetrain. It would be rather heavy car even without drivetrain at all, which is kind of surprising considering that it is made of aluminum.

Motor is induction motor (AC asynchronous induction motor). Perhaps you think of "inverter" instead of "induction".

Bubba2000 | 8 March, 2013

Duh! Sorry, I had a dense moment. With 14,000 rpm, got to have a reduction gear. Yes, Tesla got their act together. I read the blog comparing the AC induction motor with the brushless DC motor. The Tesla induction motor was by far the better choice. Especially since the company does not have to depend on rare earth magnets that are heavy.

EcLectric | 8 March, 2013


I'm sure the Tesla engineers are excellent and have implemented their best ideas into the car. I think if you want to contribute a new idea for a future Tesla, it needs to be much WACKIER. Something most people would find embarrassing to voice. Let's see... how about a battery that runs on gasoline? There is obviously a lot of energy locked up in hydrocarbons. If only we didn't have to light them on fire and spew the resulting fumes into the air.

EVTripPlanner | 8 March, 2013

While I don't think increasing diameter to decrease gear reduction needed and/or increase torque is needed, it has occurred to me that a 2 speed gearbox would allow 0-60 in under 3 seconds AND top speed in the 200 mph range! (the big tradeoff for the fixed ratio gearbox was between torque/acceleration and top speed)

lolachampcar | 8 March, 2013

Tesla tried and destroyed gearboxes on the Roadster. I do not think they will go back there anytime soon.

evanstumpges | 8 March, 2013

Will be interesting to see if Tesla considers a Switched Reluctance (SR) motor in future vehicles. They've got a number of advantages over induction motors. They are starting to gain traction in a number of applications ranging greatly in both size and power.

scriptacus | 8 March, 2013

@Brian H - "An axle and tire spinning that fast with a 2:1 reduction gear would make the car move about 1200 ft/sec, or just over 750 mph., or Mach 1."

... you say this like it's a bad thing.

Brian H | 8 March, 2013

Judging by the size of this 335kW motor, they would never fit in a car.

bobinfla | 8 March, 2013

Other problem, at Mach one the range drops to only 300 yards.

Electron | 8 March, 2013

Bob, the idea is that you coast for the remaining 200 miles to your destination.

olanmills | 8 March, 2013

You guys have thought about this before, I see.

Joyrider | 8 March, 2013

Just think of the reduction charging you'd get slowing down from Mach 1...

evanstumpges | 11 March, 2013

@Brian H.

That 335kw (350hp) Nidec SR motor pictured isn't really relevant for an EV. This is a heavy, high torque industrial motor. To illustrate this point, I looked up the specs on an a similar 450hp Baldor AC Induction industrial motor. The diameter is 24.25" and the length (excluding the gear mounting shaft) is 30.62.

Generally SR motors can be build the same size or smaller than equivalent AC Induction motors.

Chuck Lusin | 11 March, 2013

I like 335K model, I could pop the trunk, the 335 would pop up, run some O2 and methane (borrowed from SpaceX) and jump to warp 5.

deinspanjer | 12 March, 2013

@bobinfla - LOL at your 300 yard comment. My first thought on reading that was it would be the shrapnel field as the car tore itself to pieces. :)

jat | 12 March, 2013

@Eclectric - that is already available - you can reformulate natural gas to get hydrogen and then run it through a fuel cell. You can do the same with gasoline, though you still get some of the emissions from what is left over.

Brian H | 12 March, 2013

300 yds? The stopping range would be way longer than that. Jets take almost a mile to come to a stop, from lower speeds!

EcLectric | 12 March, 2013


I saw an article in which a team from one of the oil companies put a small 'plant' in the bed of a pickup truck to crack the hydrogen from gasoline and then run it through a fuel cell to power the truck. Unfortunately, the plant mostly filled the bed of the truck, and there was no re-charging, so it was still a fuel-based vehicle.

I wonder if anyone has tried starting from a simple hydrocarbon (such as methane), pulling the energy out of it as electricity, and then putting the energy back in (charging) to restore the methane to its original state. As it is, this could be done with water and electrolysis, but the 'high energy' state of water is hydrogen and oxygen gas, which take up too much space.

In other words, carbon is nature's way of storing large amounts of energy in a small volume and mass. We know this is possible, but we don't know how to get the energy in and back out in a reversible and efficient way.