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

[croman]

Everyone says they can do all these magic things with the new Roadster "because its so expensive" but it isn't that expensive. Its only 30% more expensive than the P100D. Granted, in 2020 batteries will be cheaper and more plentiful but still, this car shames $1M+ cars and costs a fraction of that. Something has to give.

Put me down for 2170 cells + double stacked battery. The battery modules on the 3 are differently shaped but likely could be converted to the 200kwh of the Roadster (10 modules). I could see them just as easily using 18650s (32 modules).

 

[Krazaak]

Everyone says they can do all these magic things with the new Roadster "because its so expensive" but it isn't that expensive. Its only 30% more expensive than the P100D. Granted, in 2020 batteries will be cheaper and more plentiful but still, this car shames $1M+ cars and costs a fraction of that. Something has to give.

Put me down for 2170 cells + double stacked battery. The battery modules on the 3 are differently shaped but likely could be converted to the 200kwh of the Roadster (10 modules). I could see them just as easily using 18650s (32 modules).

I don't think there's any magic here with the roadster. A 200 kWh battery back can clearly put out the 1100+ horsepower required for 250 mph, two of the P rear motors plus a standard front can easily make the 10,000 Nm with anything over a 7.5:1 drive ratio. The range is nothing more than a byproduct of the battery needed to produce the sustained power for speed. The biggest question is the transmission, my bet is on a 2-speed gearbox.

It's not going to be light, but torque vectoring will make it more nimble in the turns than would seem possible. It remains to be seen if they'll be able to pull off the kind of track performance that comes with the other super cars or if it'll just be king of the straight line.

And the price is a joke, in my opinion, $200,000 is an absolute bargain. A Model S P100D with carbon ceramic brakes, carbon fiber rims, 250+ mph rated tires and a spare 100 kWh battery pack would cost more than $200,000.

 

[ggnykk]

That's is far too optimistic. You're setting yourself up for disappointment, if you're planning on getting one.

The battery pack alone will weigh in the area of 900 kg/1984 lb. For comparison, an original Roadster without battery pack weighs 852 kg/1878 lb. Adding 75 kg/165 lb for the driver means the bottom line is 1827 kg/4027 lb. There's no way it will weigh less than that. This is a larger car, and the Elise/Roadster is built to be extremely light. I expect they'll be able to use the battery pack for a lot of structural strength and use more carbon fiber, but on the other hand, they'll be stuffing in three motors vs one, plus more creature comforts, two more seats, etc. I think 1900 kg is probably close to spot on.

Here is the official specs of Model 3. Are you saying that the new roadster is heavier than the steel construction Model 3?? Extremely unlikely. Remember that the new roadster is also physically smaller than Model 3.

• Curb weight:
  • 3549 lbs. (Model 3)
  • 3814 lbs. (Model 3 Long Range)
• Weight distribution:
  • 47% front, 53% rear (Model 3)
  • 48% front, 52% rear (Model 3 Long Range)

 

[ggnykk]

Everyone says they can do all these magic things with the new Roadster "because its so expensive" but it isn't that expensive. Its only 30% more expensive than the P100D. Granted, in 2020 batteries will be cheaper and more plentiful but still, this car shames $1M+ cars and costs a fraction of that. Something has to give.

Put me down for 2170 cells + double stacked battery. The battery modules on the 3 are differently shaped but likely could be converted to the 200kwh of the Roadster (10 modules). I could see them just as easily using 18650s (32 modules).

Even double stack the battery won't get you to 200 kwh in the new roadster. Model 3 long-range model battery is 75 to 80 kwh (depends on which source you believe). So let's double stack that battery only get you to 160 kwh. Also, remember that Model 3's wheel base is longer than the new roadster. The physical dimension and the math just don't add up to the double-stack battery theory that you have.

It is super clear to me that Tesla has some new battery technology (with much higher energy density) that is working at laboratory level right now. And Tesla will be using the super expensive new roadster to first commercialize the new battery tech in the market. That new battery would be very expensive and can only be produced in extremely low volume. Perfect fit for using new roadster to get the initial R&D and high production costs out of the way, before it can trickle down to the next version of Model S/X/3 in around 2021 or 2022.

 

[mongo]

Also, remember that Model 3's wheel base is longer than the new roadster.

What is your source for that? Image analysis I've done shows it to have longer WB than the 3. With enough room between wheel wells for double stack 200 kWh 2170 pack.

 

[ggnykk]

What is your source for that? Image analysis I've done shows it to have longer WB than the 3. With enough room between wheel wells for double stack 200 kWh 2170 pack.

Look here: Comparing new Roadster exterior dimensions to original Roadster

Counting pixel is way more accurate. Wheelbase for new roadster is right around 108 inch. Model 3 is 113 inch.

 

[Krazaak]

Even double stack the battery won't get you to 200 kwh in the new roadster. Model 3 long-range model battery is 75 to 80 kwh (depends on which source you believe). So let's double stack that battery only get you to 160 kwh. Also, remember that Model 3's wheel base is longer than the new roadster. The physical dimension and the math just don't add up to the double-stack battery theory that you have.

It is super clear to me that Tesla has some new battery technology (with much higher energy density) that is working at laboratory level right now. And Tesla will be using the super expensive new roadster to first commercialize the new battery tech in the market. That new battery would be very expensive and can only be produced in extremely low volume. Perfect fit for using new roadster to get the initial R&D and high production costs out of the way, before it can trickle down to the next version of Model S/X/3 in around 2021 or 2022.

There's nothing that says the battery packs can't be 3 or even 4 layers deep where the body shape permits. Nothing about the cost of the new Roadster makes me think there's new battery technology at play. $200,000 may sound like an expensive car, but it's nothing compared to the prices of the cars that Roadster competes with.

 

[ecarfan]

Also kind of confused with the 200kWh concept, Musk said they are staying at 100 for S and X, as its a good balance of range and price and weight. Now they say 200 in the roadster, totally destroying the other models in range and giving everyone the idea that in 3 years we will have 200kWh in the S and X.

The 100kWh is a good balance of range and price and weight. Part of the reason for the new Roadster’s high price is the 200kWh pack, which is needed to achieve the acceleration, top speed, and range goals that Elon apparently set for the car. That 200kWh pack size does not indicate that the S and X are going to get that pack in 3 years.

 

[ecarfan]

They're going to need auto closing doors on this as my short arms won't reach that far to grab the door.

I suspect the production Roadsters in 2020 will have powered doors like the S and X now have. It appears the prototype Roadster does not have powered doors.

That photo showing how the door sill is cut out to allow you to get your feet out of the car more easily is quite interesting.

 

[gregd]

Ok, so how do they get the battery pack inside that (slightly) shorter wheelbase? Remember, in addition to the battery between the wheels on the Model 3, there's also the motor. On the Roadster, there's two of them in the back. If you look at the Semi, they have them staggered, and those are supposed to be the same motors as are on the Model 3. I'm guessing they can't fit two of them inline between the wheels. Granted the Roadster's not sporting Dualies, but do you think they can get two motors and the gearing box(s) in the same space as the single one on the Model 3? Or, are the motors outside the wheelbase? Or above?

 

[shokunin]

If the wheelbase is shorter, they're most likely not using the same skateboard frame or pack dimensions. The Roadster looks wider than a 3 so if they lose a few inches in wheelbase length but gain a few inches in width, they could actually end up with more cells.

 

[gregd]

Hmmpf. Hadn't considered that. If it's wider than the Model 3, it might not fit in my garage...

 

[mongo]

Hmmpf. Hadn't considered that. If it's wider than the Model 3, it might not fit in my garage...

The pixel counting I did said it was very similar to the 3.
Nope too wide for your garage, bring it to mine, pretty sure it will fit.

 

[bonnie]

Report from folks that sat in prototype was that seat was quite elevated... like a double stack of batteries

I didn't think it was that elevated. It was definitely easier to get out of than the original Roadster, but it didn't seem THAT high. They had an employee standing by the passenger side when the test ride was over, ready to offer a hand for those who couldn't pop up on their own.

 

[mongo]

I didn't think it was that elevated. It was definitely easier to get out of than the original Roadster, but it didn't seem THAT high. They had an employee standing by the passenger side when the test ride was over, ready to offer a hand for those who couldn't pop up on their own.

Would you say the floor was about a foot off the ground?

 

[ggnykk]

If the wheelbase is shorter, they're most likely not using the same skateboard frame or pack dimensions. The Roadster looks wider than a 3 so if they lose a few inches in wheelbase length but gain a few inches in width, they could actually end up with more cells.

I agree with your assumption that the new roadster has shorter wheelbase, and wider in width than the model 3.

 

[ggnykk]

There's nothing that says the battery packs can't be 3 or even 4 layers deep where the body shape permits. Nothing about the cost of the new Roadster makes me think there's new battery technology at play. $200,000 may sound like an expensive car, but it's nothing compared to the prices of the cars that Roadster competes with.

If they stack the battery 3 layers or 4 layers deep in even part of the wheelbase, the new roadster would be way heavier than Model 3. I don't think the Tesla designer would be that stupid.

Also, remember that Elon and Tesla like simple and elegant design. A lot of people suggested to Elon before that they can pack Model S and X rear trunk and the frunk with more batteries to extend the range, but they keep saying no to it. The car would be carrying a lot of "dead weight" all the time. It is a diminishing return equation if u try to stack batteries in every open space as possible in a car. The more battery you add to it, it would add range, but it would negate part of the range because of higher energy consumption per mile (because your car is now heavier with the extra batteries). Elon and their team know this fact for years and years.

Like I mentioned before, I am pretty sure that Tesla is achieving the 200 kwh battery with new battery chemistry that has a much higher energy density than even the latest's Model 3 cell. The new roadster would simply have a single-stack battery between the wheelbase (just like Model S/X/3 nowadays)

 

[Yggdrasill]

Here is the official specs of Model 3. Are you saying that the new roadster is heavier than the steel construction Model 3?? Extremely unlikely. Remember that the new roadster is also physically smaller than Model 3.

• Curb weight:
  • 3549 lbs. (Model 3)
  • 3814 lbs. (Model 3 Long Range)
• Weight distribution:
  • 47% front, 53% rear (Model 3)
  • 48% front, 52% rear (Model 3 Long Range)

Yes. 200 kWh battery adds a lot of weight. Probably around 450 kg. And another two motors probably adds at least 100 kg. That's around 1200 lb. Adding the driver, that would mean a 200 kWh Model 3 with three motors would weigh around 5200 lb. I'm assuming Tesla would be able to eliminate 1000-1200 lb from the body/glider on the Roadster vs Model 3. That seems challenging, but not impossible.

 

[Yggdrasill]

If they stack the battery 3 layers or 4 layers deep in even part of the wheelbase, the new roadster would be way heavier than Model 3. I don't think the Tesla designer would be that stupid.

Now you're starting to get it. And a 1.9 second 0-60 mph time, 4.2 seconds 0-100 mph time, 8.9 second 1/4 mile and 620 miles range isn't stupid.

Also, remember that Elon and Tesla like simple and elegant design. A lot of people suggested to Elon before that they can pack Model S and X rear trunk and the frunk with more batteries to extend the range, but they keep saying no to it. The car would be carrying a lot of "dead weight" all the time. It is a diminishing return equation if u try to stack batteries in every open space as possible in a car. The more battery you add to it, it would add range, but it would negate part of the range because of higher energy consumption per mile (because your car is now heavier with the extra batteries). Elon and their team know this fact for years and years.

The weight hasn't been added to increase range, it's been added to increase battery power and therefore performance.

Like I mentioned before, I am pretty sure that Tesla is achieving the 200 kwh battery with new battery chemistry that has a much higher energy density than even the latest's Model 3 cell. The new roadster would simply have a single-stack battery between the wheelbase (just like Model S/X/3 nowadays)

There's nothing indicating that such a chemistry exists.

 

[ggnykk]

Yes. 200 kWh battery adds a lot of weight. Probably around 450 kg. And another two motors probably adds at least 100 kg. That's around 1200 lb. Adding the driver, that would mean a 200 kWh Model 3 with three motors would weigh around 5200 lb. I'm assuming Tesla would be able to eliminate 1000-1200 lb from the body/glider on the Roadster vs Model 3. That seems challenging, but not impossible.

If Tesla uses new battery tech (which is most likely the case) for the 200 kwh battery, the energy density per cubic volume or weight is a lot higher than the model 3 battery. So that 200 kwh battery could be a lot lighter than you think.