Dual Electric Motors - does it reduce range? Possibility of FWD only?

[wycolo]

The red line for the rear motor is currently a bit past 120. The proposed front motor is geared to red line @~160 mph or even more. Thus during high speed cruising torque would be biased toward the front motor which would be running at a much more efficient rpm. Very interesting.
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[CmdrThor]

AWD will add significant cost. Think what a driveunit costs. Of course the front one can be smaller but this isn't a $500 piece no matter how you look at it. Given the warranty issues up to now, I can see why people wouldn't want double the problems (potentially).

I personally think greater efficiency with 2 motors will be very small and not worth the cost. Maximizing regen - sure. I think you might eek out .05% with that.

Torque steer? Would that really be a problem with a traction controlled EV?

Sounds like you should go into the business of selling EVs. Good luck with that.

 

[ElSupreme]

Torque steer? Would that really be a problem with a traction controlled EV?

I drive a FWD Ford Focus Electric (as well as the Model S) and yes torque steer is a huge issue with the Ford. Probably the most glaring drive problem. That and an open differential make for some interesting acceleration when the wheels are turned.

 

[aronth5]

The red line for the rear motor is currently a bit past 120. The proposed front motor is geared to red line @~160 mph or even more. Thus during high speed cruising torque would be biased toward the front motor which would be running at a much more efficient rpm. Very interesting.
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And how do you know the proposed front motor will be geared this way?

 

[wycolo]

Read it here in another thread. Such a neat trick that it's got Bingo! written all over it. :biggrin:
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[sigurdi]

One problem with Model S and winter driving with slippery roads have been regen.
When regen in high going into intersections and ice/snow on road, the rear of the car have lost traction and start moving sideways.
This will be eliminated with AWD and 70/30 or 60/40 balancing regen front/rear like the breaks is working.

Rear weel tire wear, with tire rotation should also be less of a problem.

Two smaler driveunits (eks two of the Model3 units), would give better performance than one large.
Produce smaler units in high volume, could make the price not to bad, compared to one larger Model S.

 

[CroDriver]

The real answer is... It depends

An intelligent torque/power distribution strategy can improve efficiency. A "dumb" system will consume more energy.

Here's an example simulation showcasing the power consumption at constant speed with varying front/rear distribution:

 

[scottf200]

Pretty interesting graph! So 63/37 may be good

The real answer is... It depends

An intelligent torque/power distribution strategy can improve efficiency. A "dumb" system will consume more energy.

Here's an example simulation showcasing the power consumption at constant speed with varying front/rear distribution:

 

[RobStark]

Maybe not in Los Angeles, but here in Chicago, AWD is significantly better in poor weather conditions than RWD (based on my track & street experience with Porsches of both configurations). The torque-steer isn't nearly as noticeable as you would imagine, unless you're a very aggressive driver. On anything less than a track car, AWD is going to be a much better option for a car driven in all 4 seasons.

Huh? I never made a counter argument. AWD is superior in all conditions. My beef is with people saying Tesla should make a FWD car. That would just be dumb. AWD is the way to go.

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I passed a lot of rear-wheel cars stuck on the side of the road. AWD is even better.

Where those RWD BEVs? Of course AWD is better.

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AWD will add significant cost. Think what a driveunit costs. Of course the front one can be smaller but this isn't a $500 piece no matter how you look at it. Given the warranty issues up to now, I can see why people wouldn't want double the problems (potentially).

I personally think greater efficiency with 2 motors will be very small and not worth the cost. Maximizing regen - sure. I think you might eek out .05% with that.

Torque steer? Would that really be a problem with a traction controlled EV?

The numbers that have been tossed around are $1200 for the from unit. The early problems where problems with a startup manufacture going from 500 cars a year to 500 cars a week.


Tesla begs to differ. That is why RWD will not be an option on Model X. It will likely be more efficient with superior driving dynamics.

Torque steer would be a problem with a 300hp FWD vehicle.

Likely the motor driving the front wheels will be ~100hp. With 300+ driving the rear.

 

[John Malzone]

thanks for this! I asked this same question at their Garden City, Long Island store over a year ago. The spokesperson's comments indicated that they had not incorporated this yet. But I glad that it seems they have. It makes so much sense.