Gen III Range & Pricing Speculation

[raymond]

If the weight is 35% less, it needs 35% less energy to drive it.

As richkae said: No. The rolling resistance may be around 35% less, but that only makes up a small portion of the energy required to drive the car. A 35% lighter car will accelerate around 35% faster (given the same energy to accelerate) and in stop-and-go traffic less energy will be wasted (although with regen the advantages of a lighter car are less than with an ICE).

What reasons (pro and con) would Tesla have to build Gen III using aluminium vs. steel? It basically seems a cost trade-off towards acceleration. And for a mass-market car that trade-off may be different than for a premium sedan. But perhaps Tesla being "used" to aluminium the once-off costs will be higher for steel?

 

[JRP3]

Gen III will be smaller which will immediately give a lower CdA (and thus reduced drag). A lower Cd may be hard, but I'm not sure. Does anyone here know if a smaller (width and length) car would typically have a lower or higher Cd? I would think a smaller car being "boxier" would typically have a higher Cd, but not having a background in aerodynamics I could be 100% wrong.

Smaller frontal area is a large part of the picture, but so is the shape and the way it tapers in the rear. The Audi A2 looks rather boxy but had a pretty low cd Audi A2 - Wikipedia, the free encyclopedia

 

[richkae]

If Tesla could take something like this and tweak it I think they could have a nice looking car with very low cd.

View attachment 6801

http://en.wikipedia.org/wiki/Volkswagen_XL1#2011_model

If they made that an EV I would buy.

 

[richkae]

True, but giant wheels and giant wheel wells look better. They're actually the same size as what's on the Model S currently. I figure you can improve the Cd just by removing the side mirrors and reducing the width of the car. Not sure if reducing the length really matters. The purpose of that would be to reduce the weight and differentiate it from the Model S. You're got to justify the additional cost of the Model S somehow. By limiting the passengers to only 4 it would appeal to an entirely different kind of customer. Younger and more budget conscious.

Drag is CdA, where A is area. Reducing the width will reduce A, which helps. They can't remove the side mirrors, they are required by law. I would love to see them try to change the law, but I bet ICE manufacturers fight them and it will take a long time.
By having the same size wheels on a smaller car - the Cd will go up, not down - because more of the car is wheel well.
Without improving aerodynamics and rolling resistance you are not going to get 160 miles out of 30kWh.
The biggest aerodynamic flaw of the current Model S is the giant wheels.

 

[JRP3]

Folding mirrors with a camera would help.

 

[vfx]

... They can't remove the side mirrors, they are required by law. I would love to see them try to change the law, but I bet ICE manufacturers fight them and it will take a long time.....

All cars would benefit. Why not a coalition of efficiency minded automakers?

Start a list by finding all auto prototypes/design studies/concepts built without side mirrors.

 

[richkae]

All cars would benefit. Why not a coalition of efficiency minded automakers?

Start a list by finding all auto prototypes/design studies/concepts built without side mirrors.

Cars that need the efficiency ( EVs ) benefit disproportionately more than gas cars.
Yes it would be like cutting off your nose to spite your face, but I don't think it would be the first time.

 

[dsm363]

Nice. Everything looks right about it except the price. At $58k I wouldn't bet against you in the Tesla prediction pool. As it stands though, I feel like it'd be stealing cookies outta your cookie jar

I think it says $38,000 on the picture which sounds about right.

 

[Fredrik S]

As richkae said: No. The rolling resistance may be around 35% less, but that only makes up a small portion of the energy required to drive the car. A 35% lighter car will accelerate around 35% faster (given the same energy to accelerate) and in stop-and-go traffic less energy will be wasted (although with regen the advantages of a lighter car are less than with an ICE).

What reasons (pro and con) would Tesla have to build Gen III using aluminium vs. steel? It basically seems a cost trade-off towards acceleration. And for a mass-market car that trade-off may be different than for a premium sedan. But perhaps Tesla being "used" to aluminium the once-off costs will be higher for steel?

Sure, I got a bit carried away :smile: The more I live the more I learn, as Schwarzenegger once said.
I asked some people who know these things, and they said, a 35 % lighter car would reduce the energy needed by 6 %. That would mean that a lighter and smaller Gen III would need 80 kwh to drive 300 miles, if CD is the same. Let's say a smaller car, improves CD by 10 %. That gives you a 16% smaller battery than the Model S to drive 300 miles, about 70 kwh.
Let's say TM get the batteries for $175 per kwh. A 300 miles battery pack for Gen III would then cost 12 250. To sell the car for $39 950 after incentitives (the same sum as the incentative, $ 7500, is the 20% profit), would mean TM has $27 700 to spend on production. And they will not need that. How much do you think the car will cost to produce without the battery?

 

[jerry33]

Sure, I got a bit carried away :smile: The more I live the more I learn, as Schwarzenegger once said.
I asked some people who know these things, and they said, a 35 % lighter car would reduce the energy needed by 6 %.

That assumes the car is the same size. It also depends on the driving done. Weight means very little on highway trips. Reduce the frontal area, use more aerodynamic styling, put on a sensible tire size, and reduce the motor size and you should be able to easily get a 25% and perhaps as much as a 50% range increase.

 

[stopcrazypp]

Rather than guessing, it's instructive to look at the best in the industry right now, the Fit EV at 118MPGe vs Model S 89MPGe. That's 32.5% better. That includes charging losses.

If we look at pure battery range, it's 82 miles on 20kWh = 4.1 mi/kWh. Model S is 265mi on 85kWh = 3.1mi/kWh. That's 32.3% better.

I'm not sure how much more can be squeezed out. Keep in mind, the Fit EV uses a battery that likely has much lower internal resistance than the Model S's. Also in terms of aerodynamics, smaller cars in the compact class tend to be taller and shorter in length. This makes it actually harder to get the same Cd of the Model S. In terms of weight, the Fit EV uses a steel chassis, much like the Gen III likely will (which will make it harder for weight reduction).

In summary, for the Model S vs the Fit EV you get about 32.5% better efficiency/range and from 30% less weight and 16.5% more CdA (rectangular), details below:

The Fit EV is 3252lbs vs 4,647.3lbs for the Model S. 1395.3lb difference (exactly 30% difference).

Cd of Fit EV is ~0.29 (14% better than the 0.34 of the gas Fit).
Frontal Area (just a rough rectangle, not actual) = 67.7"W * 62.2"H = 4210.94 square inches.
CdA (rectangle) = 1221.2 square inches

Cd of Model S is 0.24.
Frontal Area = 77.3"W * 56.5"H = 4367.45 square inches.
CdA (rectangle) = 1048.2 square inches

So Fit has a 16.5% higher CdA (rectangle).

http://automobiles.honda.com/fit-ev/specifications.aspx
http://www.teslamotors.com/models/specs

 

[JRP3]

The Fit battery does have lower internal resistance and can safely use a larger portion of it's capacity, but it also has lower energy density, so it probably is heavier per kWh.

 

[WhiteKnight]

Cd of Fit EV is ~0.29 (14% better than the 0.34 of the gas Fit).
Frontal Area (just a rough rectangle, not actual) = 67.7"W * 62.2"H = 4210.94 square inches.
CdA (rectangle) = 1221.2 square inches

Cd of Model S is 0.24.
Frontal Area = 77.3"W * 56.5"H = 4367.45 square inches.
CdA (rectangle) = 1048.2 square inches

So Fit has a 16.5% lower CdA.

The number for the Model S looks to be less than the Fit not vice versa. 1048.2 versus 1221.2.

 

[vfx]

Tesla was way off on their weigh goals. I would think they would rein that in on the next car giving better range.

 

[Doug_G]

Tesla was way off on their weigh goals. I would think they would rein that in on the next car giving better range.

As I've mentioned elsewhere, I think the overriding desire to have an across-the-board 5-star crash rating led to extra weight. All engineering is a compromise, and something has to give... more mass = more robust.

 

[stopcrazypp]

The number for the Model S looks to be less than the Fit not vice versa. 1048.2 versus 1221.2.

You are right, edited my original post for correctness. I guess I really have to do an actual CdA analysis for good numbers, since the rectangle is too rough (apparently the Fit EV is 2.2 inches higher than the normal Fit from a higher ride height).

And it's hard to quantify what's the effect purely from weight, since the the Leaf is lighter than the Focus EV, but the Focus is more efficient. Probably looking the differences between a mid-sized to full-sized sedan vs a compact (ideally using the same engine) might show the pure effect of weight and CdA better.

 

[zachster]

One of the most interesting bits from the Q2 conference call was about the Gen 3 battery chemistry (very last question of the Q&A):

Jesse Pichel – Jefferies

I guess it not quite as exotic as picking up your Mercedes from Stuttgart, but I guess you can give them a burger and send them on their way. But you made an interesting comment, Elon, about battery pack replacements allowing the car a better range versus today. You said this before. When can we expect the next battery chemistry improvement, and what’s your roadmap for that?

Elon Musk

I think it’s probably with the Gen III that we’ll see a change in the fundamental chemistry, as we did with Roadster. With Roadster we went from a cobalt cathode to a nickel-cobalt aluminum cathode, and effectively a few percentage increase - roughly [50%] increase in both gravimetric and volumetric [energy density]. And then also a drop in cost, because of the much lower cobalt content. I can’t comment on the specifics of some of the technologies that I’m aware of, because of confidentiality agreements, but I can say I’m highly optimistic about seeing substantial reductions in cost per kilowatt hour in the three to four year time frame.

I'm reading this as Tesla plans to transition ALL it's battery packs to the next chemistry advance. With reservations on Model S being a year out and Model X production being 1 and 1/2...I think we're not too far from the point it would make sense to postpone a reservation to take grab the next battery chemistry.

Then again, with this attitude, you would never be satisfied with your electronics purchase. Thoughts?

 

[stopcrazypp]

One of the most interesting bits from the Q2 conference call was about the Gen 3 battery chemistry (very last question of the Q&A):



I'm reading this as Tesla plans to transition ALL it's battery packs to the next chemistry advance. With reservations on Model S being a year out and Model X production being 1 and 1/2...I think we're not too far from the point it would make sense to postpone a reservation to take grab the next battery chemistry.

Then again, with this attitude, you would never be satisfied with your electronics purchase. Thoughts?

With that attitude, you will have to keep waiting because by the time the next chemistry advance is in production, the next one after that would be in planning phases in 3-4 years.

It does make sense however to wait out the first generation of a product for all the bugs to be worked out. Usually the second generation would be a lot more polished.

 

[vfx]

... phases in 3-4 years.

It does make sense however to wait out the first generation of a product for all the bugs to be worked out. Usually the second generation would be a lot more polished.

Same think here though. Is the X a second generation? With AWD and crazy doors maybe not. Is the Bluegenlll 2nd generation? Smaller all new form factor, new battery chemistry, Elon surprises, maybe not. Roadster ll? High power, handling and on and on and on...

 

[stopcrazypp]

Same think here though. Is the X a second generation? With AWD and crazy doors maybe not. Is the Bluegenlll 2nd generation? Smaller all new form factor, new battery chemistry, Elon surprises, maybe not. Roadster ll? High power, handling and on and on and on...

I'm thinking more in the lines of the next model year of the Model S. Not something that is necessarily completely new. The Model X is quite close given it shares the same platform, but you make a good point about the doors and AWD.

Roadster II is essentially an entirely new product, even though it keeps the same name. I'm thinking something more in the lines of Roadster 2.0 and 2.5, which are a relatively minor refinement of a 1st gen product.

The general idea is you have a year or so where consumers have evaluated the product and any early bugs and kinks would have been worked out by then (or at least discovered).