New AWD Motor Info from fueleconomy.gov

[mongo]

Agreed... I was surprised it actually reduced range however... I was hoping that perhaps increased gearing ratio would have offset the lack of efficiency gains but not going to a slightly smaller rear motor, and perhaps kept range the same rather than getting an increase like on the S.

So I suspect not being able to sleep the rear motor may factor in.

The PMSR motor is more efficient that the AC Induction, so they sleep the AC motor on the 3.
If they changed the rear gearing or motor winding, they may have gotten a boost, but I'm guessing it was miniscule compared to the effort involved.

 

[scaesare]

The PMSR motor is more efficient that the AC Induction, so they sleep the AC motor on the 3.
If they changed the rear gearing or motor winding, they may have gotten a boost, but I'm guessing it was miniscule compared to the effort involved.

Plus, I wonder how practical it is to sleep am SR motor....

 

[mongo]

Plus, I wonder how practical it is to sleep am SR motor....

Yeah, back during the PM/ AC front motor debate, the point was raised that the rotor magnets could cause drag due to induced eddy currents...

 

[ℬête Noire]

Plus, I wonder how practical it is to sleep am SR motor....

Was it ever hard-confirmed the Model S D rear motor sleeps rather than the front motor?

 

[scaesare]

Was it ever hard-confirmed the Model S D rear motor sleeps rather than the front motor?

I seem to recall something that confirmed that, but don't remember if it was a tweet, or dome diagnostic monitoring, etc...

 

[brianman]

Regarding S vs 3 AWD range impact...

Isn't it a harder for any efficiency gain to overcome the weight impact on the 3 simply because the (additional) motor proportion of the overall vehicle weight is higher?

Picking a random number, if the motor is 100 pounds it adds 2.6% weight to a 3800 pound (3) vehicle but only 2.0% weight to a 4900 pound vehicle (S).

 

[remlemasi]

8 days into LR RWD ownership and I am already getting FOMO...

 

[scaesare]

I seem to recall something that confirmed that, but don't remember if it was a tweet, or dome diagnostic monitoring, etc...

To answer this more definitively, here it is from JB himself:

Q: Which drive unit is able to sleep, front or rear?
With the P85D we put the large, rear, drive unit to sleep while cruising. We choose to sleep the rear unit since the new generation small front drive unit is actually more efficient at converting battery DC electricity into mechanical shaft power. So we benefit from using the small, front drive unit more of the time when it can provide all of the torque requested. In the 85D both drive units are the same and we can sleep either unit, front or rear to best optimize efficiency.

 

[ℬête Noire]

To answer this more definitively, here it is from JB himself:

Interesting that the front motor of the P (and probably both motors on the D, then) was actually a gen step in tech w/better efficiency**, so of course it'll bring combination up anyway. Which means that it isn't necessary the front motor that is best to run strictly by virtue of driving the front wheels, it's just that it was a more efficient motor.

So whether or not the SWRPM can effectively sleep is moot, as it's the motor you'll normally want to power when driving on only one axe.

It'd be interesting to see the actual mix on use for solo drive between the front and back on the 85D, although kinda academic here I guess.

** Actual size difference between the two might have been an issue, also, depending on where highway cruise load puts them on their efficiency curves.

 

[scaesare]

Interesting that the front motor of the P (and probably both motors on the D, then) was actually a gen step in tech w/better efficiency**, so of course it'll bring combination up anyway. Which means that it isn't necessary the front motor that is best to run strictly by virtue of driving the front wheels, it's just that it was a more efficient motor.

So whether or not the SWRPM can effectively sleep is moot, as it's the motor you'll normally want to power when driving on only one axe.

It'd be interesting to see the actual mix on use for solo drive between the front and back on the 85D, although kinda academic here I guess.

** Actual size difference between the two might have been an issue, also, depending on where highway cruise load puts them on their efficiency curves.

There's also the gearing difference on the S.

I do wonder if that's also present on the 3, and assume it is.

 

[ℬête Noire]

There's also the gearing difference on the S.

I do wonder if that's also present on the 3, and assume it is.

I would be entirely unsurprised if there is. I would be surprised if it was the same balance as the S, though, given the sleep preference now is going to be strongly (solely?) front and the different performance profiles the motors will have.

I expect we'll need to wait until well into the fall to have a solid answer on it, for some brave soul to pull one apart. I expect one of the teardown companies will take a run at a P when it comes out.

Some dyno work may give some hints at it that we could infer, before that?

 

[lairdb]

Not that I'm a gearhead -- but is there a fundamental difference in the weight transfer under heavy acceleration vs. a car with a more conventional CG? Wondering if that affects the targeted front/rear power distribution.

 

[mongo]

Not that I'm a gearhead -- but is there a fundamental difference in the weight transfer under heavy acceleration vs. a car with a more conventional CG? Wondering if that affects the targeted front/rear power distribution.

The shift depends on the height of the CG above the ground and the wheelbase. The low CG of the pack and drive units reduces the shift when accelerating or decelerating. Front still gets more during regen and rear during launch, AWD will help on the track due to the former.

 

[T34ME]

I hope some of you smart peeps can answer two questions:

1. It is my understanding that the 3LR, 3D, and P3D all have the same battery pack. Why do the 3D and P3D have the same range (310 miles) when they are less efficient (116 MPGe, 29kWh/100 mi.) than the 3LR (130 MPGe, 26kWh/100 mi.)?
2. Am I right in expecting the 3SR will have the smaller 188kW motor?

 

[ℬête Noire]

• It is my understanding that the 3LR, 3D, and P3D all have the same battery pack. Why do the 3D and P3D have the same range (310 miles) when they are less efficient (116 MPGe, 29kWh/100 mi.) than the 3LR (130 MPGe, 26kWh/100 mi.)?

Math magic!

• Am I right in expecting the 3SR will have the smaller 188kW motor?

The motor isn't physically smaller, it's the same motor. However it'll probably have the current limited at a similarly lower level as the AWD's rear.

 

[SageBrush]

It is my understanding that the 3LR, 3D, and P3D all have the same battery pack. Why do the 3D and P3D have the same range (310 miles) when they are less efficient (116 MPGe, 29kWh/100 mi.) than the 3LR (130 MPGe, 26kWh/100 mi.)?

Tesla under-reported the LR, as allowed by EPA rules

 

[PessimiStick]

I hope some of you smart peeps can answer two questions:

1. It is my understanding that the 3LR, 3D, and P3D all have the same battery pack. Why do the 3D and P3D have the same range (310 miles) when they are less efficient (116 MPGe, 29kWh/100 mi.) than the 3LR (130 MPGe, 26kWh/100 mi.)?
2. Am I right in expecting the 3SR will have the smaller 188kW motor?

Intentional underrating, and software. All 3 cars have the same physical rear motor.

 

[Krash]

So AWD is 147kW + 188kW for 335kW and PAWD is 147kW + 211kW for 358kW. Performance is not even 10% more power? Seems a bit strange, no?

The biggest difference will the be maxtorque setting, not any power. That is what people notice in the first two seconds of acceleration. No way can the difference in 0-60 be attributed to just the difference in maxpower because that car w 446Nm torque and 358kW power only does a non rollout 4.26 0-60. More importantly the car would feel like the RWD for the first two seconds, so no way that happens.

My bet is the rear motor can currently handle more torque and that they increase the rear torque max and total torque max settings in the P from 450Nm to 575Nm. If that is true and Tesla optimizes the front motor for high speed power. it looks like this in yellow...

...and if true my bet on the AWD is no increase in torque so consequently most will not notice the 0-60 difference because it will simply be that the car continues to accelerate for slightly longer at max torque until the new higher power limit of 335kW. Highlighted in orange. I built this on the @DarthPierce modelling. After DarthPierce checks my work I'll put it in the performance Metrics.

My bet is the induction motor is optimized for high speed power not low end torque. This would be amazing in quartermile and halfmile times shown above. If I am wrong then those numbers will be off because the power will drop from the field weakening (Back EMF) at high speeds. Likely to roadster will have that low speed rear and high speed front motor optimization.

There is a substantial difference from the Model S in that the rear motor in the non-P Model S is physically smaller than Model S P. Here it is the same size motor is both and the D is just having less current run through it. It'll be interesting to see both the P and D run on a dyno to get an idea of the differences in the shape of the power curves that Tesla has programmed for them.

There aren't really programmed power curves. There are maxtorque and maxpower settings that, combined with the BackEMF of the motor combination chosen create that performance shape. But in the Model 3 RWD the maxpower may not even get reached with the current motor characteristics of field weakening or Back EMF. You don't need to get on a dyno to measure these. You could do it from your iphone or android device with a little math to calculate the torque before the API stopped working. Here's hoping that API stop is just a change in the API that hasn't been caught yet by the third party API developers.

...it's a software limitation...appears to be the same battery pack in all LR cars... (which is 1200 amp max output...

This. Exactly.

...Tesla are sandbagging the performance in software...I'm hoping that Tesla uncorks it a bit more once they work through the backlog of deliveries...

Since this is a source of differentiation between AWD and P as well as between the 3D, P3D, and all S models, Tesla would have to uncork a bunch of cars. Could happen. There might be some magic in the new S drive units for increasing torque. Probably not in the S batteries.

...I expect we'll need to wait until well into the fall to have a solid answer on it, for some brave soul to pull one apart...

All we'd need is one highspeed runlog over the API (assuming it gets fixed) or early AWD and P adopters to hookup the CANbus adapter in the 2. But a dyno works too.

 

[mongo]

Agree on hitting max current/ torque (traction?) before hitting max power.
But you lost me here:

..and if true my bet on the AWD is no increase in torque and most will not notice the 0-60 difference because it will simply be that the car continues to accelerate for slightly longer at max torque until the new higher power limit of 335kW.

My bet is the induction motor is optimized for high speed power not low end torque. This would be amazing in quartermile and halfmile times.

If we assume the pack is the same on all LR3s, then the peak output power of the pack (before SW limiting) is the same for all motor configurations. As such, at the lower RPM, the limit is the current the motor can handle (torque). So why wouldn't the AWD have higher total torque than RWD given that the front motor can provide torque beyond what the rear motor can (up to the max pack power limit)?

I'm guessing the front motor is setup for low end power more than high end for a couple reasons: Tuning it toward the low end improves the effect of regen. Most driving will be done at sub 100 MPH, so that is the normal useful power band for drivers. Under launch, the power split due to tractions will be, what like 40/60? So for 0-60 the sweet spot is a front motor with 2/3 the torque of rear. Of course, during braking/ regen the opposite is true.

 

[ℬête Noire]

All we'd need is one highspeed runlog over the API (assuming it gets fixed) or early AWD and P adopters to hookup the CANbus adapter in the 2. But a dyno works too.

Can you lay out for me, roughly, the math and inferences used to get the gearing ratio of each drive unit from that?