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

[daniel]

You probably could almost double energy density today if you halved battery longevity. It would work for a super expensive Roadster. You’d have to buy a new battery pack every 5 years or so. I always thought the car was super cheap at $200k/$250k, so it could work.

Cost-wise, perhaps it could work if people felt this was a half-million dollar car. But emotionally, people would be unhappy having to replace the battery every 5 years.

I read about a car so exotic that it came with your own personal mechanic. I think the car was not street-legal. So it was for racing or just doing laps on a racetrack.

I'm not quite sure what the point is of a street-legal car that does zero to sixty mph in 1.9 seconds, but I don't think a street-legal car would go over well if it needed a new battery every five years. Unless they charged enough up front to include a new battery at no extra charge every five years for the next twenty years. Sort of like some companies bundle the maintenance service into the car price. But then, I have no idea who are the potential customers for Roadster II. I had hoped Roadster II would be in the same price class as Roadster I, and a little quicker than the S-P100DL. It makes sense that they want to make the quickest street-legal car in the world, but I really think the battery has to last the life of the car. Or at worst, one replacement at 10 or 15 years.

 

[Brando]

Rimac C_Two they will make 25 or 125 or I'm not sure and I think only $1.2 Million each.
BUT it might well beat the Tesla 2020 Roadster.
anyway you can check it out and maybe available next year??

Rimac Automobili C_Two hypercar — A car alive with technology.

 

[Cosmacelf]

Rimac C_Two they will make 25 or 125 or I'm not sure and I think only $1.2 Million each.
BUT it might well beat the Tesla 2020 Roadster.
anyway you can check it out and maybe available next year??

Rimac Automobili C_Two hypercar — A car alive with technology.

The car might be “alive with technology”, but their website doesn’t work on an iPad.

 

[Brando]

The car might be “alive with technology”, but their website doesn’t work on an iPad.

Glad to know that my giving up on Apple doesn't just save me money.
Is this why Tesla doesn't use Apple CarPlay??
Or is this why people often refer to Model S as having a big iPad on the dash?

PS- to solve all computer problems is easy - just get rid of all your computers.

Not to worry, Few can even consider such an expense.
Sure I'll never see one in real life - maybe on Jay Leno's Garage?

 

[daniel]

Rimac C_Two they will make 25 or 125 or I'm not sure and I think only $1.2 Million each.
BUT it might well beat the Tesla 2020 Roadster.
anyway you can check it out and maybe available next year??

Rimac Automobili C_Two hypercar — A car alive with technology.

Gad! What a horrid web site. It is hard to look at, and harder to move through, and I didn't see any actual information. You quoted a possible cost and availability date, but I could not find those on the web site. It claims 1.85 seconds zero to sixty (one-foot rollout) but I could not find whether this was the time measured on a run of a prototype or a calculated estimate based on theoretical considerations. I could not even find whether this company has ever built a car before.

They say it has "bespoke technology." What the Donald Duck is "bespoke technology"? I don't think that actually means anything.

ETA: I also could not find whether they even have a prototype, or just the intention of building one. (Or scamming investors and not even doing that.)

 

[Reciprocity]

I very much doubt Tesla will create a third cell shape. People here seem to think it no big deal to create a taller, squatter cell. It is a big deal, lots and lots of R&D required to make it work, then a retooling of a huge factory to build them. I think the 2170 cell will be their one and only cell for at least 10 years...

Exactly. The retooling at the scale Tesla is operating where every machine is purpose built for speed and efficiency would be crazy. You would be better off cooling a new plant. I thought maybe they had a different cell for the semi based on the specs, but really it's not necessary to achieve their goals. My assumption was that if 18650 was great for consumer electronics but only marginally adequate for cars necessitating the 2170 which is optimal for autos. Well the same idea would be applied to semis and later aircraft or large ships. But now I don't think it's really required, in part because the semi had more room for cells, so it's really a cost and weight issue more then energy density. The biggest challenge for the semi is not the energy density but the recharge cycles with little degradation. It points to something like NMC 811 for the semi instead of NCA like the S/X. But the roadster would need the most energy dense cells to pack in as many KWh in a small space as possible. And cycle rate is not as important because $200,000 cars are but usually daily drivers.

 

[Cosmacelf]

Gad! What a horrid web site. It is hard to look at, and harder to move through, and I didn't see any actual information. You quoted a possible cost and availability date, but I could not find those on the web site. It claims 1.85 seconds zero to sixty (one-foot rollout) but I could not find whether this was the time measured on a run of a prototype or a calculated estimate based on theoretical considerations. I could not even find whether this company has ever built a car before.

They say it has "bespoke technology." What the Donald Duck is "bespoke technology"? I don't think that actually means anything.

ETA: I also could not find whether they even have a prototype, or just the intention of building one. (Or scamming investors and not even doing that.)

“Bespoke” is one of my most hated words. I’d only use it if I wanted to sound like a total douchbag.

 

[mongo]

My assumption was that if 18650 was great for consumer electronics but only marginally adequate for cars necessitating the 2170 which is optimal for autos.

I think they looked at size since they were going to be making lots of them along with all the new machinery, so they had a clean slate. From their analysis, the 2170 was the optimum size for a cylindrical cell in general (and is used in both the 3 and Powerwall/ Powerpack)

But the roadster would need the most energy dense cells to pack in as many KWh in a small space as possible. And cycle rate is not as important because $200,000 cars are but usually daily drivers.

Again my opinion: the driving force behind pack size/chemistry on Roadster is hitting the acceleration and top speed numbers (power vs energy). With a fixed gearbox, the higher top end calls for more motor torque at the low end, so high current.
The 600+ mile range will reduce SOC usage in daily driving, it seems too nice to leave in garage.

 

[Cosmacelf]

Who are we kidding? No one is going to get 600 miles in a Roadster 2 since no one will be able to drive that slow in it

 

[mongo]

Who are we kidding? No one is going to get 600 miles in a Roadster 2 since no one will be able to drive that slow in it

Oh, you know someone is going to spend a week setting a new 2,000km single charge drive record.

Tesla Model S 100D Sets Production EV Range Record Of 1,078 km/670 Miles On Single Charge

 

[MikeBur]

Gad! What a horrid web site. It is hard to look at, and harder to move through, and I didn't see any actual information.

They say it has "bespoke technology." What the Donald Duck is "bespoke technology"? I don't think that actually means anything.

*Hard* to look at? Try using an iPad, lol (pic below)

Bespoke is effectively “custom”, though more used when something is hand-crafted/created.

 

[Sonic86]

Still no clue how they will get 200kWh into the Roadster

The Model 3 LR has a pack density of 150wh/kg

Scale up to 200kWh and that's over 1300kg of batteries

Which is insanity for a supercars

Even a 30% improvement over Model 3 is still 1000kg

Can't really be more than 500kg pack weight for handling/power to weight ratio

Crazy how little progress has been made with battery density when you think about it

Roadster 2008 117wh/kg = (53kWh, 450kg)

Model 3 2017 150wh/kg ( 75kWh, 500kg )

Roadster 2020 200wh/kg ( 200kWh, 1000kg)?

 

[AWDtsla]

Still no clue how they will get 200kWh into the Roadster

The Model 3 LR has a pack density of 150wh/kg

Scale up to 200kWh and that's over 1300kg of batteries

Which is insanity for a supercars

Even a 30% improvement over Model 3 is still 1000kg

Can't really be more than 500kg pack weight for handling/power to weight ratio

Crazy how little progress has been made with battery density when you think about it

Roadster 2008 117wh/kg = (53kWh, 450kg)

Model 3 2017 150wh/kg ( 75kWh, 500kg )

Roadster 2020 200wh/kg ( 200kWh, 1000kg)?

Density goes up as you fit more cells into the pack. The shell and auxillary parts are very heavy, it does not double for doubling the size of the pack. Seems entirely achievable.

 

[MP3Mike]

The Model 3 LR has a pack density of 150wh/kg

You have to remember that the Model 3 battery pack contains a lot of parts that the Model S&X pack does not. For example the charger, DC-DC converter, HV junction box, etc...

So it isn't easy to compare the density to other cars.

 

[James Anders]

So what would be wrong with a 100kWh Roadster with 300 mile range, significantly lower weight and more affordable.

 

[mongo]

So what would be wrong with a 100kWh Roadster with 300 mile range, significantly lower weight and more affordable.

Dropping half the pack would mean giving up over half of its performance (acceleration and regen). It would have half the available power, but more than half the weight. The useable SOC window (in kWh) would also shrink by more than 50%. Basically it would be a restyled, slightly more efficient S P100DL.

 

[daniel]

So what would be wrong with a 100kWh Roadster with 300 mile range, significantly lower weight and more affordable.

Dropping half the pack would mean giving up over half of its performance (acceleration and regen). It would have half the available power, but more than half the weight. The useable SOC window (in kWh) would also shrink by more than 50%. Basically it would be a restyled, slightly more efficient S P100DL.

Or to say the same thing in different words: Half the battery would mean fewer amps available for acceleration. Also 600 miles range would mean that all but the most extreme extreme drivers would be able to go an entire driving day without a charging stop. Destination charging alone would be sufficient. (Though Level 2 charging would take 20 hours to charge from empty. Your destination charger would have to be a supercharger.)

I think 100 kWh would be plenty. I think a lot of us wanted Tesla to make a new Roadster that would basically be an upgrade from the Old Roadster. Musk apparently wants the quickest street-legal super car in the world. It will give Tesla serious bragging rights. And maybe they'll still make a reduced version later.

 

[Cosmacelf]

Yes, drop $50K off the Roadster 2 price tag with a smaller battery and less performance, and that would satisfy a lot of people. If they did that, it would be a year or two after first production.

 

[scaesare]

I do wonder if the announced pack sizes for both the roadster and 500-mile semi are predicated on a planned energy density gain at the cell level.

 

[Cosmacelf]

I do wonder if the announced pack sizes for both the roadster and 500-mile semi are predicated on a planned energy density gain at the cell level.

My guess is yes. We had 1st gen Roadster cells in 2008, Model s/x cells in 2012. Model 3 cells (gigafactory) in 2017. 2020 would seem to be a good time for a new generation of cells.