How can Dual motor get 310 Mile Range

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#21
One thing that hasn’t been mentioned yet in this thread is that the rear motor in both AWD and RWD M3s is not an induction motor, instead it’s a variant of a permanent magnet motor, which is unique to the 3. That’s got to account for some of the difference between the 3 and the S when it comes to single vs. dual motor.

(Source: https://electrek.co/2018/02/27/tesla-model-3-motor-designer-permanent-magnet-motor/)
 

garsh

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#22

oey192

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#23
Yes, you can. It lets you use physical braking less because you have more total regen capability. Furthermore, a front motor is in a better position for regen than a rear one because the center of gravity shifts forward when decelerating.
If we know for sure that Tesla has tuned it such that the AWD does indeed slow down more quickly when using regen from both motors vs. the single motor then you are right: there will be some scenarios where you will have the opportunity to get a little more back via the AWD vs. the RWD.

My point was that if you slow down from 60 MPH to 4 MPH in an RWD car you will recapture the same amount of energy as you will if you slow down from 60 MPH to 4 MPH in an AWD car
 

KarenRei

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#24
If we know for sure that Tesla has tuned it such that the AWD does indeed slow down more quickly when using regen from both motors vs. the single motor then you are right: there will be some scenarios where you will have the opportunity to get a little more back via the AWD vs. the RWD.

My point was that if you slow down from 60 MPH to 4 MPH in an RWD car you will recapture the same amount of energy as you will if you slow down from 60 MPH to 4 MPH in an AWD car
Gently, yes. Aggressively, no.
 

RoadToLevel5

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#25
As MelindaV states, the dual-motor S is actually *more* efficient than the RWD version. In that case, the rear motor is geared for acceleration, while the front motor is geared for highway efficiency. The better highway efficiency of the front motor makes up for the added weight (that also means the Model S is a front-wheel drive car during normal highway cruising ;)).

In the case of the Model 3, it turns out that the AWD version is less efficient than the RWD version. During EPA range testing, the RWD version ended up with a range of 334 miles, while the AWD version received a range of 308 miles. But in both cases, Tesla asked for a "variance" to advertise them both as having a range of 310 miles, which the EPA granted.
What explains the lower range on Model 3 AWD compared to RWD and the higher range on Model S AWD compared to RWD?

If the EPA tests were inadequate for the Model 3 AWD, you would think Tesla would have cried foul.
 

MelindaV

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#26
If the EPA tests were inadequate for the Model 3 AWD, you would think Tesla would have cried foul.
the EPA ratings are provided by Tesla to EPA with documentation of their findings. EPA is not doing the testing and providing the numbers, except in few instances where they re-test a vehicle themselves (I think this came up on one of the Model X versions) to confirm the manufactures claims.
 

garsh

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#27
What explains the lower range on Model 3 AWD compared to RWD and the higher range on Model S AWD compared to RWD?
The S/X have two induction motors of fairly equal efficiency. The rear one is more powerful, and geared for acceleration. The front one is less powerful, and geared for efficient highway cruising. When driving on a highway at steady-state, they use only the front motor. So the AWD versions get better mileage.

The 3 has an efficient PM motor in back, and a less-efficient induction motor up front. So the 3 is most efficient by preferring the rear motor for all driving. The front motor provides two benefits: more powerful acceleration when needed, and more powerful regeneration when slowing down. But neither of those benefits helps with highway cruising efficiency - it just adds weight and rotational mass, which hurts highway cruising efficiency.
If the EPA tests were inadequate for the Model 3 AWD, you would think Tesla would have cried foul.
It sounds like you're under the impression that the EPA is performing the tests. They do not. Each manufacturer tests their own vehicles. After the tests provide raw numbers, the manufacturers can then ask the EPA for variances in what they actually advertise.
 

PNWmisty

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#29
Yes, you can. It lets you use physical braking less because you have more total regen capability. Furthermore, a front motor is in a better position for regen than a rear one because the center of gravity shifts forward when decelerating.
While I agree there are limited situations in which the dual motor could recapture more braking energy I will point out that regen braking in the RWD LR Model 3 is strong enough that I never use the brakes above 4 mph. So, for me, the AWD would not recapture more energy except perhaps on snow/ice where the regen could be transferred to the front where there is a bit more traction available for braking. But this would be a very small difference. On a road race course, yes, the AWD could probably capture a lot more regen energy.
 

tivoboy

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#30
While I agree there are limited situations in which the dual motor could recapture more braking energy I will point out that regen braking in the RWD LR Model 3 is strong enough that I never use the brakes above 4 mph. So, for me, the AWD would not recapture more energy except perhaps on snow/ice where the regen could be transferred to the front where there is a bit more traction available for braking. But this would be a very small difference. On a road race course, yes, the AWD could probably capture a lot more regen energy.
A little while back someone posted some data about how the dual motor in the S, and any incremental regen that it might provide was essentially negated by the increase in weight. Does that sound reasonable in this case? Certainly the M3 weighs much less than an S, so getting over the power/weight threshold for regen to be able to produce a tiny incremental amount of energy could be possible.
 
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#31
Can anyone with a model 3 with AWD post the efficiency numbers they are seeing?

As someone waiting on a non-p AWD car I’m very interested if this car can make it 300 miles on a charge of highway driving. Or if a 250 mike round trip with no charging access can be done easily.

This point greatly interests me as I live in the land that Tesla forgot (also known as North Dakota).

Sorry if this has been posted before, but I’ve been scouring all forums since AWDs started delivering trying to find some efficiency numbers.
 

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#34
Yes, you can. It lets you use physical braking less because you have more total regen capability. Furthermore, a front motor is in a better position for regen than a rear one because the center of gravity shifts forward when decelerating.
If you never need to use brake-pad braking (except for the final stopping of the car), then I don't see how you can get more energy from regen with two motors than with one. You could do *faster* regen with two, as you get larger generating capacity with two generators running, and this may help people who are more reactive than proactive in their driving in getting some extra KWh through regen, as the regen could brake the car harder (assuming that's allowed by the software) and thus reduce the amount of brake-pad braking (lost energy) done by the driver.. (In a related, but not directly relevant, question, I don't know if the recharging process used in regen can absorb the full power generated by both motors at once.)
 

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#35
There are a variety of limits in the regen system that may or may not be reached - current to the battery, power from the front motor, traction on the front wheels, ditto for the rear, interaction with friction braking, behaviors programmed by software for various reasons including traction and stability. We know the first - maximum current to the battery - varies according to state-of-charge and temperature. Tesla engineers know how all this plays out, but it's probably too complicated for mere owners to figure out.

I've read that the most difficult thing to develop for the Prius was the brake pedal, including providing the simulated resistance during regen and the transition to friction. There's an indicator that helps you know when you're braking too hard for regen alone. It's interesting that Tesla avoids that complexity by restricting the brake pedal to friction, and the regen to the right pedal.
 

Bernard

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#36
There are a variety of limits in the regen system that may or may not be reached - current to the battery, power from the front motor, traction on the front wheels, ditto for the rear, interaction with friction braking, behaviors programmed by software for various reasons including traction and stability. We know the first - maximum current to the battery - varies according to state-of-charge and temperature. Tesla engineers know how all this plays out, but it's probably too complicated for mere owners to figure out.

I've read that the most difficult thing to develop for the Prius was the brake pedal, including providing the simulated resistance during regen and the transition to friction. There's an indicator that helps you know when you're braking too hard for regen alone. It's interesting that Tesla avoids that complexity by restricting the brake pedal to friction, and the regen to the right pedal.
You point out one of my favorite features of the Teslas: the brake pedal is the mechanical brake, regen is controlled by the accelerator pedal. This is way better than attempting to blend regen and friction braking in the brake pedal -- the sense of control in the car is much stronger and regen is entirely automatic; I think Toyota, with a hybrid car, part legacy, part forward-looking, chose a legacy-style control for acceleration and braking, whereas Tesla did the right thing and invented a new paradigm.
 

Jayc

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#37
I've read that the most difficult thing to develop for the Prius was the brake pedal, including providing the simulated resistance during regen and the transition to friction. There's an indicator that helps you know when you're braking too hard for regen alone. It's interesting that Tesla avoids that complexity by restricting the brake pedal to friction, and the regen to the right pedal.

In Toyota HSD, letting go off the accelerator enables regen - I know because I have one. And pressing brake peddle increases regen + applies friction brakes later. In Gen3 HSD, handover to friction brake happens early whereas in Gen4 I think regen can cope with higher speeds. I agree that the Tesla way is simpler and that is how technology evolves.
 
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garsh

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#38
If you never need to use brake-pad braking (except for the final stopping of the car), then I don't see how you can get more energy from regen with two motors than with one.
This is how (notice, @KarenRei originally said "more regen capability", which refers to power, not energy):

When slowing down, weight is shifted from the rear tires to the front tires. The more quickly you attempt to slow down, the more weight you are removing from the rear tires. The tire's friction (aka rolling resistance) is linearly proportional to weight. So at some point, your rate of deceleration reduces far enough that the tire "skids". Regen has to be limited to avoid that.

If you were to take a car that is otherwise identical, but has the motor on the front wheels, then you'll find that you can greatly increase regen without skidding. As you slow down harder, the front tires take on more weight, which increases their friction, which means you can regen at higher power.

Now, you are correct in that the total amount of energy generated in the end will be similar in both cases, but with a front motor, the regen power available is greater.
 

ADK46

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#39
In Toyota HSD, depressing the accelerator enables regen - I know because I have one. And pressing brake peddle increases regen + applies friction brakes later. In Gen3 HSD, handover to friction brake happens early whereas in Gen4 I think regen can cope with higher speeds. I agree that the Tesla way is simpler and that is how technology evolves.
Just sold our '11 Prius in anticipation of the Tesla! If you mean "letting off the gas", yes - some regen braking occurs to simulate normal engine braking. I've mentioned elsewhere that hybrid FWD regen braking can lead to a disconcerting moment when one wheel on the front axle skids on snow: the differential means the other front wheel does nothing, and there's no braking at all until the system senses the trouble and kicks in the (four) friction brakes. To go even more OT, a good strategy on very slippery roads when braking is to disengage the clutch - remember clutches? - to take engine braking out of the calculations. I'm curious about how the Tesla - designed in sunny California - will substitute its judgement for mine when I lift off the right pedal.