Oct 11, 2014
NoMoDinos I've already confirmed my order, but was just wondering. I had assumed it would be a situation like the 85 vs P85, where both are capable of the same range given the same driving style. Any ideas?�
Oct 11, 2014
pmppk I would guess that it's the 21" Wheels... since they are required on the P85D they have to be included in the range estimate.�
Oct 11, 2014
green1 Except the P85+ doesn't have less range than the S85, so that doesn't answer it.�
Oct 11, 2014
amzng_ev The S85D has two smaller motors, which are more efficient. It would still have more range if it was on 21s.�
Oct 11, 2014
stevezzzz The S85D has better range because its AWD system uses two smaller motors while the P85D uses the standard, larger P85 rear motor and a smaller motor for the front. So the S85D's drivetrain weighs less than the P85D's drivetrain (less weight == more range) and the overhead losses of the smaller motor are less than that of the larger motor.�
Oct 11, 2014
green1 The P85 had a larger motor than the S85, and yet they had the same range...�
Oct 11, 2014
stevezzzz No, they have the same motor: the P85's control electronics are just able to provide more juice to it than the S85's do. When driven the same, they consume the same amount of battery power.�
Oct 11, 2014
NoMoDinos Good thoughts. I couldn't get the guys at Tesla corporate to give me a straight answer. I think I'll try sending an email to the engineering folks. My wife made me promise I wouldn't bug the very awesome and very busy Jerome Guillen with stupid questions anymore.�
Oct 12, 2014
David_Cary The range quoted is not EPA. I suspect part of what they are doing is compensating for the tires in this quoted range.
EPA requires tire sizes to be correct on model variations for testing when certain criteria are met. Obviously, P85+ was never tested (or reported) separately from S85 because they do not have exactly the same range (whether that is relevant is another issue).
With this announcement, Tesla is giving all sorts of varying ranges which is over and above what the EPA would require.
And then there is the motor size.
The actual EPA variations on range will be smaller since city driving will likely be slightly worsened in certain circumstance with AWD - more weight. Also at slower speeds, rolling resistance matters more so tire variations matter more. The P85D looks the best on the highway but may have the worst low speed range of any 85 kwh S (who cares of course since you don't usually need tons of range in the city).�
Oct 12, 2014
Svenssons Wonder what Tesla could do with 4 smaller engines regarding range. S85Q with 350 miles range and even better acceleration and top speed? Replace battery to lighter battery with same energy and we might see a S85Q with 400 miles range and yet better acceleration because of less total weight?
Larger battery capacity will take longer time to charge and might lead to queues at the SC. Longer range is possible without increasing battery capacity and is preferable in my opinion.�
Oct 12, 2014
deonb Exactly the opposite. Batteries charge much quicker at the bottom half of the curve, so larger batteries will reduce the queue size.
Today, if you need 250 miles of range at a SuperCharger, you'll be there for 75 minutes.
If there was hypothetically a 170kw/H battery, and you need 250 miles of range, you'll be there for 45 minutes.
Now of course, if you wanted 500 miles of range at a SuperCharger on a 170kW/h battery, you'll be there for 120 minutes. But then you'd have 500 miles of range, and can skip the next 2 SuperChargers.�
Oct 12, 2014
Parisio How do we know the S85D has smaller motors?
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Hoe do we know S85D has two smaller motors?�
Oct 12, 2014
Bighorn It just does. Check out the order page.�
Oct 12, 2014
SCDrJ I asked my sales rep why there was only a modest improvement in performance in S85D vs S85, meaning why didn't they just keep the standard rear motor and add the front one like they did for P85D. He said that it was a conscious compromise between performance and range. So, slight performance upgrade in S85 and increased range rather than one or the other.�
Oct 12, 2014
scaesare It doesn't though. It simply specifies how much power the motor is specified to deliver, not what it's ultimately capable of.
I question if there really is going to be a rear drive unit engineering change or if this is going to be electronically limited, similar to the way a 40 was limited via software.�
Oct 12, 2014
Bighorn They have a new small motor that generates ~188 HP. Are you suggesting that by coincidence they are electronically throttling back a 380 HP motor to 188? Highly unlikely and cost inefficient.�
Oct 12, 2014
stevezzzz Fair point, but my engineer's sixth sense tells me it's got to be a smaller motor in back. They have to have a different drive train up front, just for space considerations (though it's also true that no one's seen the new frunk space in the D versions); at that point it makes perfect sense to use it in the back, too, which is where a good chunk of the increased range would come from. If the S85D and P85D shared all drivetrain mechanical components and the only difference was inverter electronics and/or software (as in the current 2WD lineup), the x85D's would both be capable of the same range.�
Oct 12, 2014
Svenssons Yes, I stand corrected but my assumption was to fully load the battery. That would take longer time but as you say, then you could skip a SC. However, less battery weight would mean less energy consumption and therefor less charging. With more efficient battery, you could choose either less weight, more energy storage or a combination.�
Oct 12, 2014
ToddRLockwood This question has been posed by many people since the D introduction. I imagine that it has to do with the gross weight and size of 4 motors vs. 2 motors that deliver the same overall performance. In-wheel motors have never been considered a viable option because of the added unsprung weight added to each wheel. The lighter the wheel load, the better as far as handling is concerned.�
Oct 12, 2014
scaesare I'm simply challenging out that the assertion of what they ARE doing being made in some posts based on what the ordering page says.
Tesla has chosen to quote what power the motor would deliver, not what it's capable of, therefore using that as an authoritative source of what the motor size must be is questionable.
We have at least two instances of a component being specifically upgraded solely based on matching the car configuration: inverter (for the P models), and 60 & 85kWh battery packs.
We also have several instances of Tesla including hardware on the car capable of more, but limited based on the configuration: 40kWh packs, supercharging hardware, motor (in the non-P), autopilot sensor package.
Obviously time will tell, but until then it's speculation, and thus stating authoritatively one way or the other is difficult.�
Oct 12, 2014
Bighorn Sorry, I was using an idiom with a person whom I know that posed the question. I assumed you were being contrarian to make a point, but you must admit that the economic and weight costs of leaving a big motor in the rear would not sit well with any engineer or stockholder. I appreciate the validity of your argument, but I'm guessing you wouldn't be willing to make any wagers
�
Oct 12, 2014
scaesare Nah, I have no vested interest one way or the other.
I've just simply seen thing asserted on the forum many times based on non-authoritative data (hand would Perf motors, anyone?), that I strive to be careful and add/ask for clarity when I see questionable statements go by...�
Oct 12, 2014
Bighorn I'll happily recant, but for now I'm going with it�
Oct 12, 2014
brkaus The S85D also has higher top end speed. Perhaps different gearing in one of the transmissions? Not sure if there is a specific rpm that would be more efficient with an electric motor?�
Oct 12, 2014
jerry33 The difference in the amount of heat produced by the inverters because of the different gearing is the most convincing argument right now.�
Oct 12, 2014
Bighorn I think that's a fairly good assumption. It will be interesting to see what the gear ratios to the two motors are ie will the rear motor get a different gear ratio or will the smaller front motor have more of an overdrive gear? Peak torque starts to drop off at a certain RPM far shy of peak RPMs (I forget--8 or 9K perhaps), so a second gear has always been desirable. Doing that with two separate single geared motors rather than having a transmission required to shift simplifies the process and protects the gear box.�
Oct 12, 2014
NoMoDinos It will be interesting to see what the mileage is like at varying speeds. I'm planning on plotting my energy usage per mile at a few different speeds on the same flat stretch of road and compare with a friend's P85.
(BTW, in four posts you'll hit the big jackpot!)
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You've got a whole lotta mechanical knowledge for an opthal-malologist type of feller, Big�
Oct 15, 2014
Olle It is very obvious that the 85D has small Drive Units front and rear. Some indications:
1. weight. the old rear DU weighs 150 kg and the new DU weighs 115. Ill let you add them up and then look at the weights of 85D and P85D.
2. pictures. The order page has pictures of the DUs both for the 85D and the P85D. You can clearly see how the 85D has the small DU front and rear and the P85D has the big old DU rear
Need more evidence?
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@OP: I think all the explanations people have posted are good reasons for the difference in range. I would just add that 85D probably has a combination of gear ratios, front and rear, optimized for range while the P85D probably has ratios optimized slightly more toward acceleration.�
Oct 27, 2014
Kandiru Which of course begs questions about motor longevity, especially that knowing myself (Audi S4 owner) there will be some Kalifornicators and others who will rape it at the track.
S85D future owner here also. Makes a lot more sense, I will only be sacrificing 0.1s on the 0-60 from my old car, but oh boy how I will miss the 6MT, or maibe not, to be compensated by uniform delivery of torque.�
Mar 31, 2015
henderrj It seems to me that Elon claimed the new motors were more efficient because they are newer technology. I think he said something like "2nd generation". There's also a video on the Tesla site titled "high efficiency electric drive unit" (added last November) showing off new equipment for making said units. Related?�
Mar 31, 2015
Matias I asked if there is any difference between front and rear motor. Tesla's worker said, that the front and the rear motor are geared differentially. But of course that worker might be wrong.�
Mar 31, 2015
ScepticMatt Because the new motors are more efficient (a variant of which will be used in the Model 3)
Weight is probably a pretty minor difference at high-ish speeds.�
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