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200 kWh Roadster Pack: How is Tesla Pulling This Off?

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Any possibility of different sized batteries as an option or even swappable batteries of different size? That would be one way to address the distance versus speed versus handling calculation.

Maybe. People have been speculating that a reason for the 200 kWh battery is to get the huge power needed for the 1.9s 0-60 time. So if Tesla decides to release a lower power version, maybe one that can “only” do 2.5s, then you’ll get less range, lighter battery and better handling. As people have been speculating, though, maybe the better handling you would get is marginal.

Given that this is a low volume halo car, I’m not sure it makes any sense at all to release different battery packs.
 
Maybe. People have been speculating that a reason for the 200 kWh battery is to get the huge power needed for the 1.9s 0-60 time. So if Tesla decides to release a lower power version, maybe one that can “only” do 2.5s, then you’ll get less range, lighter battery and better handling.

But Elon has said that the specs released so far are for the base version. So there is going to be a quicker version as well. I doubt they would make a slower version.
 
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Recent announcements by Elon that Tesla has a battery breakthrough in the works, and that there will be a SpaceX option package with 10 small cold-air thrusters that might enable flight, suggest that the car's 200 kWh pack may not be all that big or heavy. I'm now wondering if there's some sort of high-tech air-cooling system, which along with a next-gen battery cell with 30% greater energy density, could reduce the weight of a 200 kWh pack to roughly that of today's 100 kWh packs.
 
Elon has just tweeted:
"You have my word, Marques. Next gen Roadster will be absolutely out of this world. For those who love to drive, there is no finer car in history and we don’t think there will be another."

Any more questions?

Look, I like Elon as much as anyone, but this is the same guy that assured us, through moist eyes, that the Model X seats were going to be awesome and a friggin work of art. Instead we got second row seats that didn’t fold down.
 
Elon has just tweeted:
"You have my word, Marques. Next gen Roadster will be absolutely out of this world. For those who love to drive, there is no finer car in history and we don’t think there will be another."

Any more questions?
God-said-it.jpg

:)
 
Look, I like Elon as much as anyone, but this is the same guy that assured us, through moist eyes, that the Model X seats were going to be awesome and a friggin work of art. Instead we got second row seats that didn’t fold down.

It is indeed a work of art. There is nothing finer or more versatile than those pedestals seats for people who use the car as a people hauler as I do. There are of course people who want to use it as stuff hauler they could get versions with seats that can be folded too. Although I would never use my $100K+ car to haul plywood from Home Depot. Just use your truck or rent one.

As for if you want to believe Elon so far he has delivered everything significant he said he would "eventually".
 
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It is indeed a work of art. There is nothing finer or more versatile than those pedestals seats for people who use the car as a people hauler as I do. There are of course people who want to use it as stuff hauler they could get versions with seats that can be folded too. Although I would never use my $100K+ car to haul plywood from Home Depot. Just use your truck or rent one.

As for if you want to believe Elon so far he has delivered everything significant he said he would "eventually".

Please don’t slide the truth around. It took Tesla about a year after production start to deliver folding second row seats.

And no, Elon has not delivered everything he said he would. Full self driving is still a pipe dream. Elon also promised some sort of third party app integration for the car console, that’s probably never going to happen. Battery swap, just a head fake to get renewable credits until California took the credits away. He isn’t necessarily intentionally lieing (although the battery swap was damn close), but you can’t always take what he says as gospel. And I’m not even including his timeline estimates which we all know are crap.
 
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Look, I like Elon as much as anyone, but this is the same guy that assured us, through moist eyes, that the Model X seats were going to be awesome and a friggin work of art. Instead we got second row seats that didn’t fold down.

How does folding relate to a work of art or awesomeness?

Roadster 2020 is awesome on the whole but likely totally useless to me on the practical level. (Practical meaning I fit, not that it is fiscally practical)

Anything that can't adjust to work with my 6'8" frame fails my personal awesomeness test (I'm looking at you X front seat head rests), but I can recognize the general awesomeness.

Folding seats are practical, and for my use case, would be the version of car I'd get, but the monoposts are pretty cool and do look better when viewed through the FWD than standard types. For parents who need the back seat space for kids, the auto move/ tilt seats likely considered awesome.
 
Jeez. Just because I don’t trust all of Elon’s statements and don’t think he is always right, doesn’t mean I can’t think he’s a great person overall and like the companies he runs.

I have no problem with you don't trust Elon but that's totally irrelevant on this subject. Put you (and I too of course) out there you will not be able to achieve 0.00000001% of what Elon has done. That you don't trust what he said about the Roadster will be the best handling car out there means nothing to anyone other than to yourself.
 
Hate to put a downer here but...

Tesla might have achieved battery energy density and cost breakthroughs

“We think we have come up with some pretty cool breakthroughs on energy density and cost of the battery pack. It’s going to be pretty great.”

"As for the cost at the pack level, Musk sees Tesla achieving that important price point of $100 per kWh for the overall battery pack in less than two years.

Musk also added that he sees Tesla achieving a
30% improvement in volumetric energy density within 2 to 3 years using current proven technology that “needs to be scaled and made reliable.”

Pack.

Volumetric.

Extrapolations.


Just saying.
 
Don’t take this the wrong way, but mass and weight are proportional and easily convertible when gravity is constant (like on earth):

Weight = mass * gravity.

Mass is no better a term than weight.

You've taken my comment totally out of context. The guy I quoted was confusing weight (as in mass) with aerodynamic downforce by suggesting they are equivalent "weights", when the latter actually has no associated mass. Of course mass and its associated weight are equivalent on Earth.
 
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Interesting thing I learned from other poster on this site:
Tire frictional coefficient decreases as force increases so more weight does decrease handling/ acceleration ability.

Yeah it's true. In layman's terms, the increase in tyre lateral/longitudinal force (cornering grip/traction) you get from increased weight is always slightly less than the lateral/longitudinal force you need to react due to the increased mass, so the net result is a loss of both lateral and longitudinal grip. It's not totally intuitive when it comes to the traction part, as people often presume more weight equals better traction, but really that only applies to weight distribution between axles rather than the overall weight. There are exceptions (e.g. when tyre loading is insufficient for the tyre compound to work in its optimal temperature range) but the fundamentals are sound. A heavy car will turn, brake and accelerate slower than a lighter car with all other parameters equal. There is no positive side to the increased weight.
 
Yeah it's true. In layman's terms, the increase in tyre lateral/longitudinal force (cornering grip/traction) you get from increased weight is always slightly less than the lateral/longitudinal force you need to react due to the increased mass, so the net result is a loss of both lateral and longitudinal grip. It's not totally intuitive when it comes to the traction part, as people often presume more weight equals better traction, but really that only applies to weight distribution between axles rather than the overall weight. There are exceptions (e.g. when tyre loading is insufficient for the tyre compound to work in its optimal temperature range) but the fundamentals are sound. A heavy car will turn, brake and accelerate slower than a lighter car with all other parameters equal. There is no positive side to the increased weight.

Tires are indeed a strange realm of frictional dynamics. One paper I saw when poking around the Model 3 braking issue was that optimum grip occurs at ~10% wheel slip. Which also explains tire wear (beyond change in effective circumference during compression).

One edge case (which is it not the point of focus and only included as an aside since it involves non-optimal frictional base cases), increased weight can benefit those of us in colder climates by allowing the tire to displace the slush on the roads.
 
Lighter is of course better but that is not the only factor. I've heard 4000 lb weight of the Roadster mentioned but could not verify it. That is not even as heavy as the Bugatti Chiron. More importantly with low CoG the Roadster sure will be able to handle better than those supercars of equal weight. Heavier weight contributes to both vertical force and lateral force. The former is actually good. Only the later would degrade handling. However the same weight sitting low has less leverage and contributes less to the lateral force than weight at higher level. That's why instead of reducing engine weight, which is hard to do, those supercars would make the engine to sit as low as possible (but still not low as Roadster's battery). That's also the reason why when some cars that could only use partial light weight materials they would put an aluminum hood before they put aluminum fenders. Anyway you can't equal a heavy battery sitting very low to a heavy ICE up high.

Another thing is of course electronic assist. Modern electronics can do a lot to fix natural mechanical deficiencies. Take the 911 for example it has the worst weight distribution imaginable and it shows when the car is drove to the extreme. But that's before Porsche added electronic controls to make the car as drivable as anything either on the road or on the track. There is no doubt the Roadster will have the most advanced computer assisted steering control we have ever seen. Rest assured Tesla knows how to get this thing done right.

Okay 3 points on this:-

1. You keep insisting that weight is good for vertical force, when it actually isn't. Braking, acceleration, cornering and tyre wear all degrade with increased total weight. I worked in F1 as a vehicle dynamicist for over a decade and never once did adding any mass to a car result in improved performance. Sure you can gain traction with a more rearward weight distribution on a RWD car, but 50/50 weight distribution is actually optimal for AWD traction. Adding weight makes everything worse. Lighter is better for performance!

2. Whatever weight the Roadster achieves with improved battery tech over the next few years, it could still be at least a few hundred kilos lighter with a shorter range battery. So therefore relative to itself with the bigger battery, handling will be much improved. It doesn't matter what other hypercars happen to weigh (and I agree some of them are way too heavy to handle well on many roads), the Roadster will still be a better handling car with a lower capacity, lighter battery pack.

3. I agree the Roadster will have better inherent handling capability than an equivalent ICE car of the same weight due to the smooth EV drivetrain and very low centre of gravity. But don't automatically expect it to out handle a signficantly lighter ICE car. The laws of physics are not up for debate here. A Model S does not handle better than a Porsche Panamera despite its inherent EV advantages, simply because the Porsche is a couple of hundred kilos lighter overall.
 
Tires are indeed a strange realm of frictional dynamics. One paper I saw when poking around the Model 3 braking issue was that optimum grip occurs at ~10% wheel slip. Which also explains tire wear (beyond change in effective circumference during compression).

One edge case (which is it not the point of focus and only included as an aside since it involves non-optimal frictional base cases), increased weight can benefit those of us in colder climates by allowing the tire to displace the slush on the roads.

Yes, wheel slip is a tricky one. 10% slip is often quoted and probably quite accurate as a round figure. It's basically a level of slip that isn't obvious wheelspin to the naked eye. I did a lot of work on F1 launch systems (before they were banned) and we often did slip mapping tests, but the results were quite unpredictable due to subtle variations in road surface (even in different patches on a grid) and tyre temperature.

You are right about driving on slush and also aquaplaning resistance is higher with increased total weight. But these are exceptions rather than the norm i.e. driving on a reasonable dry or damp tarmac road.
 
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Yes, wheel slip is a tricky one. 10% slip is often quoted and probably quite accurate as a round figure. It's basically a level of slip that isn't obvious wheelspin to the naked eye. I did a lot of work on F1 launch systems (before they were banned) and we often did slip mapping tests, but the results were quite unpredictable due to subtle variations in road surface (even in different patches on a grid) and tyre temperature.

Soo... with the dual rear electric motor Roadster, the DU can set the tire speed to an exact slip level for each wheel while also measuring the torque, creating the maximum force allowed by law(s of physics).

You are right about driving on slush and also aquaplaning resistance is higher with increased total weight. But these are exceptions rather than the norm i.e. driving on a reasonable dry or damp tarmac road.

Yah, hence my preemptive disclaimer ;) (and not getting into towing or other types of things having nothing to do with the core discussion, but everything to do with my pedantic trigger of use of absolutes :D)