Let's discuss Dual Motor range

[sreams]

Why does everyone keep thinking that dual motor = more range? It was only true on the S because two, more efficient small motors replaced a single, less efficient large motor. Model 3 RWD already has the most efficient rear motor. Adding a second motor upfront only adds weight and decreases efficiency.

If this were true, the single motor S85 would have more range than the P85D. It doesn't.

 

[kengchang]

I just hope the AWD is not like most ICE AWD that it's not engaged until the wheel is slipping

 

[commasign]

If this were true, the single motor S85 would have more range than the P85D. It doesn't.

Lol. It does. 85 has an EPA range of 265 miles. P85D has an EPA range of 253 miles.

 

[lklundin]

Not getting my hopes up. When Model S dual motor was first announced, they made a big deal about how range was improved. The P85D was initially listed with a "range at 65mph" of 285 miles. That got everyone excited about a significant bump in range and no doubt contributed to a lot of people ordering the car. When the EPA range of 242 miles (later revised to 253 miles) was revealed, there was all sorts of speculation that maybe Tesla was factoring in 21" wheels and/or 90% charge limit. Turns out, it really was just 253 miles (12 miles LESS than a regular 85, and 17 miles less than an 85D). In short, adding another motor (and leaving the original motor unchanged) makes a car heavier and less efficient.

Here's a good Tesla blog to review. TLDR, the cars are all in the same ballpark in terms of range.

Driving Range for the Model S Family

Excuse me for disagreeing, but per your own link the 85D have a improved range over the 85 of 1.8% for EPA, and from 2.9% to 3.5% for actual cruising scenarios.

The dual motor does not just add more weight (which reduces range by very little) and (some unspecified) inefficiency, it is also used to effectively provide the car with two gears, since the two motors have reduction gears with different ratios. The use of different reduction gears is also part of the design of the Tesla Semi, a vehicle where the efficiency is critical for the buyer. I believe there is a (non-tesla) source stating that the dual motor M3 will use the same approach for its two reduction gears.

So like the original poster, I would not be surprised if Tesla is actually understating the range of the dual motor (non-performance) Model 3. The motivation for that could be to not offer an M3 with a range matching that of the 100D Model S.

 

[commasign]

Excuse me for disagreeing, but per your own link, the 85D have a improved range of the 85 of 1.8% for EPA, and from 2.9% to 3.5% for actual cruising scenarios.

Yes, but that’s not the analogy we’re looking at. 85 has one large motor. 85D has two small motors. If we’re trying to predict the effect of simply adding a front motor (and leaving the original rear motor unchanged), the better analogy is to look at the P85 vs P85D. Same rear motor. Only difference is addition of a front motor. Range decreases 4-5%. That’s a fact, not an opinion.

For Model 3 LR vs Model 3 LR AWD, same rear motor. The only difference is addition of a front motor. It would violate the laws of physics for something that adds weight to also increase range.

Now, if the rear motors are different (gearing ratio as you suggested), then that’s a different story. But so far nothing Tesla or Elon has said suggests this is the case.

 

[ModelNforNerd]

Yes, but that’s not the analogy we’re looking at. 85 has one large motor. 85D has two small motors. If we’re trying to predict the effect of simply adding a front motor (and leaving the original rear motor unchanged), the better analogy is to look at the P85 vs P85D. Same rear motor. Only difference is addition of a front motor. Range decreases 4-5%. That’s a fact, not an opinion.

For Model 3 LR vs Model 3 LR AWD, same rear motor. The only difference is addition of a front motor. It would violate the laws of physics for something that adds weight to also increase range.

But where your comparison fails is that I'm speculating about the NON-peformance 3. The gear ratios will be tuned more for range than performance.

 

[commasign]

But where your comparison fails is that I'm speculating about the NON-peformance 3. The gear ratios will be tuned more for range than performance.

Model S 85 and P85 have the same motor. It’s just the inverter that’s different.

I hope you’re right about gear ratios. But again, nothing Tesla or Elon has said suggests they’ve changed anything for the rear motor in Model 3. If they have, then I agree there could be a change in range.

I’m not saying I don’t want the range to be more with AWD. Just suggesting to not assume or make your purchase solely on that assumption.

 

[ModelNforNerd]

Model S 85 and P85 have the same motor. It’s just the inverter that’s different.

So that lines up with what I just said. If the P model is set up for faster acceleration/less range, through a combination of software and inverter, we may be able to expect a similar outcome in the Model 3 between RWD and AWD variants.

even the modest percentage gains pointed out above by @lklundin translate to ~319 miles-321 miles for the 19's, and ~344-346 miles for the 18 aero's at cruising speed.

 

[commasign]

So that lines up with what I just said. If the P model is set up for faster acceleration/less range, through a combination of software and inverter, we may be able to expect a similar outcome in the Model 3 between RWD and AWD variants.

even the modest percentage gains pointed out above by @lklundin translate to ~319 miles-321 miles for the 19's, and ~344-346 miles for the 18 aero's at cruising speed.

I hope you’re right and will cheer too if that’s the case. We’ll just have to wait for the official EPA numbers and updated Model 3 owners manual (gearing ratio info) which shouldn’t be too much longer if production begins next month.

 

[ModelNforNerd]

I hope you’re right and will cheer too if that’s the case. We’ll just have to wait for the official EPA numbers and updated Model 3 owners manual (gearing ratio info) which shouldn’t be too much longer if production begins next month.

Like I said above, I would think the new drivetrain would have to be certified by the EPA. So, yes, hopefully we see some new numbers soon.

 

[lklundin]

nothing Tesla or Elon has said suggests they’ve changed anything for the rear motor in Model 3. If they have, then I agree there could be a change in range.

This reasoning is flawed.

Even an M3 with the current motor + reduction gear on the rear axle and a second motor with a different reduction gear ratio on the front axle would get a range advantage, since the front motor would work optimally at a different speed, allowing the dual motor version to work more efficiently at a greater range of speeds.

So I agree we will have to reconvene here once the (non-performance) M3 dual motor specs are out.

 

[commasign]

So I agree we will have to reconvene here once the (non-performance) M3 dual motor specs are out.

Agreed. I do hope you're right.

 

[EVnut]

I just hope the AWD is not like most ICE AWD that it's not engaged until the wheel is slipping

Don't worry. This is not new territory for Tesla. The traction control and seamless integration is mature for them now. And it is a rare thing of beauty. Look high and low, and I'll bet you don't find a complaint about how AWD works for Teslas. Note that you can't even buy a non-AWD S or X today. If Tesla wasn't trying to hit a price point for the 3, it probably never would have come with RWD. This car was designed for dual motors from the beginning. The RWD is the oddity.

Both motors are engaged at all times, and the contribution from each motor is varied in real time, instantly in response to conditions.

 

[voip-ninja]

Is Elon underselling the range on the Dual Motor 3, just as he did for the RWD variant?

The RWD 3 was tested at 334 miles of range by the EPA (with the aeros). Without aeros, it was closer to the 310 miles range that Tesla asked the EPA to publish.

When EPA specs leak for the AWD/non-P variant, what do you suspect the range will be for the 2 types of wheels?

Elon stated over the weekend (when discussing the brakes) that the regen in Dual Motors is going to be stronger than the RWD. The S variants have all seen a range bump in the AWD configs when compared to their RWD variants.

I just find it hard to fathom that we won't see ANY improvement in range with Dual Motors, and I suspect the numbers are being sandbagged again.

So, what's the "napkin math" say? 4% 5% 6%? More? Less?

4% boost: aeros= 347 miles / 19's= 322 miles
5% boost: aeros= 350 miles / 19's= 325 miles
6% boost: aeros= 354 miles / 19's= 328 miles

I don't see why Elon/Tesla would undersell the range on this car when they are going to make more profit than they do on the RWD version and this one shouldn't be any harder to build.

They would want to sell just as many AWD cars as possible.

 

[commasign]

I don't see why Elon/Tesla would undersell the range on this car when they are going to make more profit than they do on the RWD version and this one shouldn't be any harder to build.

They would want to sell just as many AWD cars as possible.

That's exactly my point. I don't think Tesla is underselling. My theory is that the LR AWD and P versions have a range pretty close to 310 miles, and that Tesla purposely downrated the LR RWD version from 334 miles to 310 miles to keep all LR models consistent. I would agree that if the AWD versions had increased range (340 miles for example), Tesla would have played that up (e.g. 315 miles advertised range) to sell more AWD cars. So that's another reason I think range is actually down a bit for AWD and P versions.

 

[dhanson865]

I'm not sure how that works, but I would think that a different drivetrain would require a new EPA test, in order for the Monroney stickers to remain somewhat accurate.

I think they HAVE TO have the EPA test AWD.

EPA numbers are self reported and only a small number of car models each year are chosen for random testing. In 2017 that percentage was near 9.58% (0.0958 if I got the math right).

It'd cost them something but not much. For example in 2017 the EPA tested 0 Tesla cars. Same for 2018 as well.

See Data on Cars used for Testing Fuel Economy | US EPA for the raw data.

Reported cars for 2017 were:
Tesla Model 3 Long Range
Tesla Model 3 Long Range
Tesla Model S 100D
Tesla Model S 100D
Tesla Model S 60D
Tesla Model S 60D
Tesla Model S 60R
Tesla Model S 60R
Tesla Model S 75D
Tesla Model S 75D
Tesla Model S 75R
Tesla Model S 75R
Tesla Model S 90D
Tesla Model S 90D
Tesla Model S P100D
Tesla Model S P100D
Tesla Model S P90D
Tesla Model S P90D
Tesla Model X 100D
Tesla Model X 100D
Tesla Model X 60D
Tesla Model X 60D
Tesla Model X 75D
Tesla Model X 75D
Tesla Model X 90D
Tesla Model X 90D
Tesla Model X P100D
Tesla Model X P100D

for 2018 the list is much shorter:
Tesla Model 3 Long Range
Tesla Model 3 Long Range
Tesla Model S 100D
Tesla Model S 100D
Tesla Model S 75D
Tesla Model S 75D
Tesla Model S 75R
Tesla Model S 75R
Tesla Model S P100D
Tesla Model S P100D
Tesla Model X 100D
Tesla Model X 100D
Tesla Model X 75D
Tesla Model X 75D
Tesla Model X P100D
Tesla Model X P100D

 

[dhanson865]

It was only true on the S because two, more efficient small motors replaced a single, less efficient large motor.

It was true because the front motor had a different gear ratio than the rear and because the car could put one or the other motor to sleep.

also per this thread the same rear motor was used in all the trims Same Rear Motor in S60 and P90D?

 

[Knightshade]

For Model 3 LR vs Model 3 LR AWD, same rear motor. The only difference is addition of a front motor. It would violate the laws of physics for something that adds weight to also increase range.

... what specific law of physics do you think "something that adds weight to also increase range" violates?

I mean, adding the first motor adds weight too, and its range is 0 without that.

While we're at it, the larger battery pack obviously adds weight and increases range too.

 

[Big1matt]

I would expect there to be maybe a slight reduction in range on the Model 3 Perfomance and perhaps a slight increase in range for the AWD LR 3. But It does seem a litte strange that all versions of the long range 3 are the same exact range stat.

 

[commasign]

what specific law of physics do you think "something that adds weight to also increase range" violates?

Take two identical cars. Add a few hundred pounds to one of them. See which one goes farther or accelerates quicker.

Gearing ratios, efficiency curves, torque sleep, etc., sounds good in theory. But any improvement from having that new front motor has to overcome those few hundred extra pounds of weight. Model 3 is a lighter car overall so the motors make up a larger percentage of the total weight compared to S and X. I’m not saying it’s impossible that EPA range is increased, I’m just trying to be realistic. In fact, I’d totally agree even now that if you compared the efficiency curve of Model 3 RWD vs AWD, along some parts of the curve AWD will come out ahead. The question is, when using the EPA test cycles, which one comes out ahead overall. In any case we’ll know very soon once the final (unadjusted) EPA numbers and updated Model 3 manual are available.