JRP3
Hyperactive Member
That is simply not true. Higher C rate cells can produce more power from a smaller pack, and if you don't care about your pack lasting 200,000+ miles you can get high C rates from lower C rate cells for short periods.
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Shocked by the new Roadster rolling out of the Tesla Semi!
- Thread starter rudholm
- Start date
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- Tags
- Roadster 2020
That is simply not true. Higher C rate cells can produce more power from a smaller pack, and if you don't care about your pack lasting 200,000+ miles you can get high C rates from lower C rate cells for short periods.
Assuming they use 21700 cells vertically, the pack is at least 7 cm tall for single stack, 14 cm for double, not including structure.
Original Roadster had wheelbase of 2.342m and width of 1.873m. Knock off 20cm on each side for structure and you have 1.9mx1.4m = 2.66 m^2.
If the Tesla cells are 3.6V 4.75Ah, then it takes about 12,000 to make a 200kWh pack. In pure area (100% density) that's 4m^2. So double stack gives a density of 4/5.32= 75%. Cylinder pack at a maximum density of 90%, so it fits.
If they use close coupled phase change cooling, they can even out and improve the temperature. This would be simplified if they stack cells sideways to provide continuous cooling channels with reversed flow in alternating tubes.
Original Roadster had wheelbase of 2.342m and width of 1.873m. Knock off 20cm on each side for structure and you have 1.9mx1.4m = 2.66 m^2.
If the Tesla cells are 3.6V 4.75Ah, then it takes about 12,000 to make a 200kWh pack. In pure area (100% density) that's 4m^2. So double stack gives a density of 4/5.32= 75%. Cylinder pack at a maximum density of 90%, so it fits.
If they use close coupled phase change cooling, they can even out and improve the temperature. This would be simplified if they stack cells sideways to provide continuous cooling channels with reversed flow in alternating tubes.
Just stumbled on a video where they showed the tires on the one on stage clearly - a very wide, low profile version of the same Pilot Sport Cup 2s that I believe the P100Ds usually wear. It's around 5:38-5:40 in this video - I can't quite make out a size, despite freezing the 4k frames:
JRP3
Hyperactive Member
Random Google result for 21700's.
Looking again the 18650's seem to be in the 3.4-3.6 range. Based on volume 4.75Ah seems reasonable.
3.6Ah puts density right at 100%, so that wouldn't fit....
rajram
Member
These pictures are courtesy of forum member SageBrush:
As noted by Saghost, tires on the Roadster are Michelin Pilot Sport Cup 2s, 265/35-20 in front, and 325/35-21 in the rear. However, these are different from the Pilot Super Sports that are optional on the Model S P100D; the MPSC2 is an R-compound tire and is standard fitment on many uber supercars, notably the Porsche 918 Spyder. The track intent and worthiness of the roadster is clear just from the choice of rubber.
As noted by Saghost, tires on the Roadster are Michelin Pilot Sport Cup 2s, 265/35-20 in front, and 325/35-21 in the rear. However, these are different from the Pilot Super Sports that are optional on the Model S P100D; the MPSC2 is an R-compound tire and is standard fitment on many uber supercars, notably the Porsche 918 Spyder. The track intent and worthiness of the roadster is clear just from the choice of rubber.
Attachments
It's because it's 620 at highway speed.
In the city it will be 1500+, on the highway it will "only" be 620 miles.
https://teslamotorsclub.com/tmc/attachments/upload_2017-11-18_15-42-29-png.261139/
They see 75 miles as highway speed
rajram
Member
Another thing to note is that the brake rotors are clearly carbon ceramic. The new Roadster will come ready to tango with the big boys! 
That's wild, departing from the EPA as typical claimed range approach. What's the source and context of that image?
Also odd that best range is achieved at much lower speeds than seen in Model S (23-25mph?). What might cause that?
I know, right? A Hypercar and yet still manages the same efficiencies as their sedans!
Awesome!
JenniferQ
Active Member
Thank goodness that worked with my SCTY stock!It just dawned on me: The Semi is a massive diversionary tactic, and not just this announcement. Elon’s going to form a Tesla Truck company, transfer all the Tesla debt and losses to that entity, then bankrupt the hell out of it. Cool if you can do it, and maybe he better get it done before the tax code changes.
;-)
Yes, I'm sure people paying for a car with this price tag would be thrilled with the prospect of its pack's range and performance rapidly degrading (/sarcasm).
There's a simple answer (the vehicle's pack doesn't fit entirely inside the wheelbase, like Model 3, and/or is 2x high), weighs a bit over 1 tonne, and a volume of around 0,4 m³ . We don't need to postulate that Tesla is going to damage cells to get the Roadster's performance.
I agree. This will use less than half the energy of the Prius. The most energy efficient non plug-in, while out performing the $1M+ Hyper-cars
I would recommend revisiting seating positions
Sell your SUV for $25k. Buy TSLA stock. Wait 3 years. Presto!
JRP3
Hyperactive Member
JRP3
Hyperactive Member
Where did I say anything like that? I'm only talking about the car used for the demo, obviously not production cars. Point being I don't think they can fit 200kWh into the Roadster platform, yet. Having the pack extend beyond the wheelbase as you suggest would expose it to greater crash intrusion, not a good idea. Making the pack twice as tall would mean the ride height would be rather tall, especially for a sports car. The easiest and most likely way to get the performance needed for the demo is to simply push the cells harder for the demo only or use higher C rate cells, again, for the demo only. In 2 or so years from now they can probably fit 200kWh into the vehicle.
Where did I go wrong?
10 cm clearance + 14 cm cell + 10 cm structure = 34cm and you are under the wheel radius of 34.6 for the fronts (265/35-20), that's seems low to me. Need to get out of the car eventually.
