A longer range Tesla

[tga]

All I am asking is what additional range could the 85 get if it was less powerful?

Much less than you think. Possibly none.

Smaller motors will not significantly increase efficiency. Electric motors are not like gasoline engines, where the is a significant loss in efficiency running an oversized gas engine.

Because of their very high efficiency, you could run a 250 HP electric motor at 1/5 power output, and a 100 HP electric motor at 1/2 output, and they will both have (approximately) the same efficiency and use the same power (37,250 kW) to produce 50 HP.

The smaller motor will be slightly lighter, so the car will be a little more efficient, but the gains won't be significant.

The D's gain range (efficiency) because of the different gearing in the front motor, not because of 2 smaller motors vs one large one.

 

[WarpedOne]

Because of their very high efficiency, you could run a 250 HP electric motor at 1/5 power output, and a 100 HP electric motor at 1/2 output, and they will both have (approximately) the same efficiency and use the same power (37,250 kW) to produce 50 HP.

Actually, that 100HP motor outputting 50HP has higher losses than 250HP motor outputting same 50HP.
Maximum power of electric motor is determined by heating constraints. One increases the maximum power by improving cooling and/or reducing resistance. Improving cooling is harder than reducing resistance - just use fatter copper wires. 250HP motor hence has lower resistance than 100HP and has lower losses at same power output.

It has a bit higher weight that offsets things in another direction.

 

[Model 3]

Not really. Why not a smaller motor in the back too?

In the P85D they chose to keep the old motor behind to give preforms model as much power and rapid acceleration as possible. In the 85D has replaced the large motor in the rear with the same small motor that they have in the front.

 

[Tasdevil]

In the P85D they chose to keep the old motor behind to give preforms model as much power and rapid acceleration as possible. In the 85D has replaced the large motor in the rear with the same small motor that they have in the front.

So because they have the same range there must be no efficiency gains between the 2 different sized motors

 

[glhs272]

So because they have the same range there must be no efficiency gains between the 2 different sized motors

They don't have the same range. The S85D with 2 smaller motors has more range than the P85D 1 small motor and 1 large motor. 295 (S85D) vs. 275 (P85D). Thus all things being equal, the smaller motor has more efficiency.

 

[Kevin Harney]

They don't have the same range. The S85D with 2 smaller motors has more range than the P85D 1 small motor and 1 large motor. 295 (S85D) vs. 275 (P85D). Thus all things being equal, the smaller motor has more efficiency.

View attachment 61550

It is not that the smaller motor is more efficient it is that the two motors can be used at each one's top effeciency for the moment thus creating a more efficient final product. At least that is how I understood it from Elon's announcement.

 

[Saghost]

They don't have the same range. The S85D with 2 smaller motors has more range than the P85D 1 small motor and 1 large motor. 295 (S85D) vs. 275 (P85D). Thus all things being equal, the smaller motor has more efficiency.

The smaller motor implemented by Tesla in the AWD model S on the (unknown) gearing Tesla chose appears to be more efficient than the larger motor implemented by Tesla on the 9.4:1 gearing it has, yes.

I think the point some other folks are trying to make is that we believe this has more to do with the other factors (most likely much taller gearing) than it does the fact that the motor is smaller in and of itself.

It might be possible to extend the efficiency improvement further, but that may have consequences beyond the reduced horsepower that aren't evident without knowing exactly what Tesla did.
Walter

 

[David99]

The Model S is designed to be exciting and fast. It's overall the most un-efficient EV on the market. (Look up EPA ratings of all EVs, the Model S is the worst). It's not because Tesla doesn't know what they are doing, it's because they designed the car to be large, comfortable and fast. These things had slightly higher priority over being the most efficient. By sizing the battery large enough they still beat everyone in range by far. It also made the car expensive but as we can see, buys want an exciting, high quality car over one that is boring and optimized for long range. Elon said they can make a car that goes 500 or more miles, but it would require so many compromises and cost that it wouldn't sell much.

The 85 has more than plenty of range. There is almost no gain in every day use if the car had a 400 mile range, but it would add significant cost and compromise space and performance.

There are very few people that drive much more than 200 miles a day and don't have access to a charger all day. Those few people don't justify designing a car for just that need. It make much more sense to invest into expanding the Supercharger network with partners because this benefits not just this small group of people, but everyone. I'm sure at some point Tesla or someone else will make a super long range EV, but it certainly won't be a big seller.

 

[Saghost]

The Model S is designed to be exciting and fast. It's overall the most un-efficient EV on the market. (Look up EPA ratings of all EVs, the Model S is the worst).

Not the worst. It's noticeably worse than the Volt/Leaf/Spark crowd, but it is better than both the Fisker Karma and the Toyota RAV4 EV.
Walter

 

[glhs272]

The smaller motor implemented by Tesla in the AWD model S on the (unknown) gearing Tesla chose appears to be more efficient than the larger motor implemented by Tesla on the 9.4:1 gearing it has, yes.

I think the point some other folks are trying to make is that we believe this has more to do with the other factors (most likely much taller gearing) than it does the fact that the motor is smaller in and of itself.

It might be possible to extend the efficiency improvement further, but that may have consequences beyond the reduced horsepower that aren't evident without knowing exactly what Tesla did.
Walter

Ok, perhaps if I word it differently. The smaller drive unit appears to be more efficient. Be it due to the fact that the motor is smaller, or the inverter is more efficient, or if it's geared differently I can't say. Just stating the facts published from Tesla.

 

[WarpedOne]

Still wrong.
Two drive units together can be / are more efficient than a single one.
Stop thinking in ICE terms.

 

[glhs272]

Still wrong.
Two drive units together can be / are more efficient than a single one.
Stop thinking in ICE terms.

Yes Two drive units together can be / are more efficient than a single one. No doubt about that.

My original point was the difference of the larger rear drive unit vs. the smaller rear drive unit and which configuration turns out to be more overall more efficient on the D series cars. Perhaps there are other factors in explaining the difference in published efficiency of the S85D and the P85D such as the wheels (19 vs. 21). However, I suspect a percentage of that difference is because of the drive units (motor, inverter, gearing). I suppose it could just be Tesla being dodgy with the numbers. Why go through the bother of redesigning the rear drive unit to make it smaller if didn't somehow improve the car?

 

[Tasdevil]

However, I suspect a percentage of that difference is because of the drive units (motor, inverter, gearing).

If the major difference is gearing, maybe tesla will look at a gearbox for gen3 and the updated s/x platform.
The front drive unit would be heavier than a gearbox too.

 

[David_Cary]

Yes Two drive units together can be / are more efficient than a single one. No doubt about that.

My original point was the difference of the larger rear drive unit vs. the smaller rear drive unit and which configuration turns out to be more overall more efficient on the D series cars. Perhaps there are other factors in explaining the difference in published efficiency of the S85D and the P85D such as the wheels (19 vs. 21). However, I suspect a percentage of that difference is because of the drive units (motor, inverter, gearing). I suppose it could just be Tesla being dodgy with the numbers. Why go through the bother of redesigning the rear drive unit to make it smaller if didn't somehow improve the car?

Cost? And they will probably use the same unit in the X. And then maybe the 3.

 

[tdelta1000]

It will come soon enough, when the battery technology is mature. To do it with today's batteries would make it 6000 pounds heavy or something.

I agree but only batt tech gets better and lighter.

 

[Red Sage]

If a Tesla can go 0 - 60 mph in 3.2 sec, why not give up on some performance (and price) to check just how much battery can be stuffed into a sedan?

This is a faulty argument for a wide range of reasons. Just because the Tesla Model S P85D is capable of reaching 60 MPH in 3.2 seconds (or less) doesn't mean you have to drive it that way. The ultimate range of a Tesla Motors vehicle is controlled by your right foot. If you stomp on the accelerator from a dead stop all day long, or constantly accelerate to demonstrate speed and quickness, or refuse to drive anywhere at anything less than the posted speed limit plus twenty-five miles per hour, then stomp on the brakes when you see a cop, you will empty the batteries sooner. Period.

Other manufacturers seem to have limited their 'economy' electric cars to a maximum 0-60 of 7.2 seconds. That is because their tiny battery packs would be emptied on a single run of 0-60 MPH otherwise. Other manufacturers also limit the top speed on their 'economy' electric cars to around 85 MPH, and some barely crest 70 MPH. That is because their tiny battery packs would be emptied in thirty minutes or less on a run of 100+ MPH otherwise. By setting arbitrary limits on performance traditional automobile manufacturers can maintain the illusion that electric cars are 'not ready for prime time'... Right up to the point where someone takes a test drive in a Tesla Motors product.

Tesla Motors allows the driver to choose how their range is affected by their driving style. Set the cruise control at a constant 65 MPH get near EPA mileage or better. 'Drive It Like You Stole It' and pray you get 200 miles... 'Drive It Like A Hippie Tree Hugger' and cruise to 400+ miles...

Tesla Motors could have limited the top speed on the Model S 85 to 85 MPH... Tesla could have limited its acceleration to a more sedate 7.2 seconds 0-60, like everyone else did... It would have garnered them pats on the back, kudos, nice try, no cigar... and none of the accolades and awards that were received... and a lot fewer sales... and a much lower stock price. Oh, and the company would be out of business now.

Battery packs of higher capacities will resolve a lot of the perceived issues. At 135 kWh a Tesla Model S would have a range of around ~420 miles. At 170 kWh it would be closer to 530 miles. At 220 kWh the range would be ~685 miles, better than even today's Lexus LS 600h. That will come come within the next decade, and far sooner than the traditional automobile industry will be able to bear.

 

[Red Sage]

There is something that people seem to be overlooking. All of the motors that Tesla Motors offers for the rear wheel drive Tesla Model S are different than they were prior to the Tesla 'D' Event. Thus, none of the 'old' motors are being used any more:

VEHICLE	WAS	NOW
Model S 60	302 HP	380 HP
Model S 85	362 HP	380 HP
Model S P85	416 HP	470 HP

The Tesla Motors website shows the EPA ratings for the OLD motors... The new motors have not been tested by the EPA -- none of them. It seems that since the new rear wheel drive cars have the same names (60, 85, P85) as before, it is still considered 'OK' to list the EPA ratings, even they were achieved using the old motors. Either that, or Tesla Motors has made a mistake, and needs to update the language on the Design Studio page.

If you'll remember, Tesla Motors estimated the range on the Model S 60 at 230 miles... and the Model S 85 at 300 miles -- before the EPA tested those cars. The official EPA range rating was lower on both vehicles 208 and 265 miles, respectively. The new Model S 60D is estimated by Tesla Motors at 225 miles -- five miles less than their estimate for the original rear wheel drive car. The new Model S 85D is estimated by Tesla Motors at 295 miles range -- five miles less than their estimate for the original rear wheel drive version.

I would not expect an EPA rating of the Tesla 'D' vehicles to have a better range rating than the original versions of the cars -- unless the EPA has learned how to properly drive an electric car since their original tests.

 

[glhs272]

There is something that people seem to be overlooking. All of the motors that Tesla Motors offers for the rear wheel drive Tesla Model S are different than they were prior to the Tesla 'D' Event. Thus, none of the 'old' motors are being used any more:

VEHICLE	WAS	NOW
Model S 60	302 HP	380 HP
Model S 85	362 HP	380 HP
Model S P85	416 HP	470 HP

The Tesla Motors website shows the EPA ratings for the OLD motors... The new motors have not been tested by the EPA -- none of them. It seems that since the new rear wheel drive cars have the same names (60, 85, P85) as before, it is still considered 'OK' to list the EPA ratings, even they were achieved using the old motors. Either that, or Tesla Motors has made a mistake, and needs to update the language on the Design Studio page.

If you'll remember, Tesla Motors estimated the range on the Model S 60 at 230 miles... and the Model S 85 at 300 miles -- before the EPA tested those cars. The official EPA range rating was lower on both vehicles 208 and 265 miles, respectively. The new Model S 60D is estimated by Tesla Motors at 225 miles -- five miles less than their estimate for the original rear wheel drive car. The new Model S 85D is estimated by Tesla Motors at 295 miles range -- five miles less than their estimate for the original rear wheel drive version.

I would not expect an EPA rating of the Tesla 'D' vehicles to have a better range rating than the original versions of the cars -- unless the EPA has learned how to properly drive an electric car since their original tests.

My understanding is that Tesla modified the way they report what the motor is capable of, not what the actual performance with the battery. Thus the RWD cars are not getting different motors. The RWD cars will have the same performance they always had. The 60kwh RWD is still limited by the battery, thus not capable of getting the full 380HP out of the motor. I guess they wanted it to be more confusing. My guess they wanted to align the RWD numbers to the AWD numbers and the AWD numbers report total HP of both motors, not necessary stating that the car can output both motors at peak (maybe they can, maybe not).

With respect to the D series cars, I fully expect they will have better range than the single motor versions, as stated by Elon himself.

 

[Red Sage]

My understanding is that Tesla modified the way they report what the motor is capable of, not what the actual performance with the battery. Thus the RWD cars are not getting different motors. The RWD cars will have the same performance they always had. The 60kwh RWD is still limited by the battery, thus not capable of getting the full 380HP out of the motor. I guess they wanted it to be more confusing. My guess they wanted to align the RWD numbers to the AWD numbers and the AWD numbers report total HP of both motors, not necessary stating that the car can output both motors at peak (maybe they can, maybe not).

With respect to the D series cars, I fully expect they will have better range than the single motor versions, as stated by Elon himself.

Uh... What?

 

[AluminiumStork]

Question: What if you take that extra 20K that is applied to the P85D Remove the P and add an E making the E85D (E for 'Extended' Range) I am sure there are some of us out there that would pay the extra cash for more range on the S (I really don't much care for 0-60 in 3.2... I am fine with my 5.2 seconds). So how much KW will 20K buy hell how much will 10K get you? Once that is figured out then we can figure out range... can it get close to 400? There are a few $110K luxury cars that can only go less than 400 miles per tank...