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Less overall drag.
Model 3 is:
- a bit lighter resulting in lower rolling resistance
- has narrower wheels resulting in lower rolling resistance
- is fitted with smaller wheels and rims resulting in lower rolling resistance
- is fitted with optimized LRR Hankook tires with lower rolling resistance
- it is a bit narrower and lower hence having smaller cross section resulting in less aerodynamic resistance
- it is supposed to be a bit more aerodynamic than S (target was 0.21, S is 0.24)
- less resistance means less power needed for some given speed and that means less losses and higher range with same amount of kWh
20% higher efficiency is thus plausible.
Rashomon
Member
Lower weight, slightly less frontal area, lower coefficient of drag (almost 15 percent), and perhaps some efficiency improvements from lower rolling resistance tires, the new inverter, and perhaps a smaller motor.
Hi, everybody. Well done to those who guessed 75 kWh correctly, who didn't estimate crazy numbers like 100 kWh and who didn't downvote others when they said 75 kWh. I always said 55/75 kWh and I got downvoted a few times by weirdos who don't understand that the Model 3 75D will have more range than the Model S 90D.
Hi, @smak. There are 3 reasons:
◘ 12.5% better efficiency because of lower drag coefficient (the shape of the car is more aerodynamic)
◘ 2.9% better efficiency because the frontal area is 2.9% smaller.
◘ 2.7% better efficiency because of weight reduction
See my range calculations HERE. I posted those on 1st Dec 2016.
Hi, @smak. There are 3 reasons:
◘ 12.5% better efficiency because of lower drag coefficient (the shape of the car is more aerodynamic)
◘ 2.9% better efficiency because the frontal area is 2.9% smaller.
◘ 2.7% better efficiency because of weight reduction
See my range calculations HERE. I posted those on 1st Dec 2016.
Pretty safe to assume/think that they will just slap a 75 kWh battery in every car and dumb it down to say a 55 or 60 kWh as they did with the S. Thoughts?
nope. Too expensive. The margins will already be pretty tight. Also that means that they are "wasting" almost 30% of the cells they put in. So for every 4 model 3 55kwh cars that are sold they wasted enough cells to make another car. Maybe in a few years when the gigafactory if fully ramped up they could do that.
Yeah thats true. So I guess they will have probably no more than 3 options? 50/55, 60/65 and a 75?
my guess would be just two options. They need to keep things simplified. That is why they are launching with no P or D.
No. They are trying to reach 30% gross margin. Click HERE to read things Elon promised to the board. Let me copy that:
Successful completion of the Model X Alpha Prototype; [completed]Successful completion of the Model X Beta Prototype; [completed]Completion of the first Model X Production Vehicle; [completed]Successful completion of the Model 3 Alpha Prototype; [completed]Successful completion of the Model 3 Beta Prototype;[completed]- Completion of the first Model 3 Production Vehicle;
- Gross margin of 30% or more for four consecutive quarters;
Aggregate vehicle production of 100,000 vehicles; [completed]- Aggregate vehicle production of 200,000 vehicles; and
- Aggregate vehicle production of 300,000 vehicles.
No, not even 3. I would expect 2 battery sizes. Btw, there is a topic here for predictions: Prediction Thread - "You Called It" In that thread, I made predictions for both of the topics you mentioned. My predictions are:
- The Model 3 won't have any software limited battery pack option when released.
- Model 3 will be released in two battery sizes, not three.
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cdub
OG 2011 Leaf / 2023 Model Y LR
Too costly. In a year or two they might make a limited 55 kWh to get people to get a Model 3. Like a 45 kWh introductory version in 2019 or 2020. Tesla would need a fully operational gigafactory pumping out tens of millions of batteries so that Tesla has enough margin to make it a worthwhile endeavor.
Thermal problem in the pack is due to power, not due to current nor voltage (there is very slight current related heat in conductors, but let's concentrate on chemical reaction only).
Definitely not. Not a single normal sized passenger vehicle will be able to receive 250kW without external cooling system. 5% charging inefficiency would be 12.5kW of heat. Only way is to make charging process extremely efficient, which might be more than 5-6 years from nowadays.
And keep in mind that the Model 3 is supposed to have a thinner margin than the Model S and Model X. That has been mentioned on many occasions. S and X are supposed to have 25% to 30% and the Model 3 was supposed to have 15% to 25% since it is a mass market vehicle. It's going to be very tough for the next few years for Elon to hit that goal.
Is it reasonable to expect that 75kWh Model 3 will have full house in the pack (8 modules)
and 55kWh pack will miss 2 modules, so 6/8 out of 75kWh = 75*0,75=56,25kWh?
Hmm, I would rather reduce cells in parallel rather than cells in series. I would want to keep
voltage near 400V on the 55kWh pack too
and 55kWh pack will miss 2 modules, so 6/8 out of 75kWh = 75*0,75=56,25kWh?
Hmm, I would rather reduce cells in parallel rather than cells in series. I would want to keep
voltage near 400V on the 55kWh pack too
Actually drag coefficient is just about the shape. The smaller frontal area will have an additional effect besides drag coefficient. In fact, you multiply the two numbers. This is the drag equation. This is from Wikipedia:
In this formula, Cd is drag coefficient. A is the frontal area. Cd*A is the drag area. Here is how it would look like:
Model S: 0.24 drag coefficient * 2.43 m^2 frontal area = 0.5832 m^2 drag area
Model 3: 0.21 drag coefficient * 2.36 m^2 frontal area = 0.4956 m^2 drag area
Why is this difference important? Because the difference between 0.21 and 0.24 is 12.5% which does not include the frontal area difference. The frontal area needs to be added as well. This means the difference becomes 15% when you calculate the drag area.
Btw, this is what frontal area means.
Amen.
(although I do sort of expect the rhetoric about uber Supercharging rates to ramp up now...)
stopcrazypp
Well-Known Member
Here I'm talking about the supercharger cabling/connectors and also the cabling inside the car to the battery.
250kW charging was achieved a decade ago in a passenger vehicle (the Phoenix Motorcar SUT). That uses a 35kWh Altairnano pack, which is a lithium titanate based pack. That has extremely low internal resistance and is a low density chemistry, so I didn't bring it up initially.
AeroVironment Achieves Electric Vehicle Fast Charge Milestone (NASDAQ:AVAV)
In the second part I talk about the pack generating 17.5kW of heat using 200kW charging. In a typical ICE, 35% of total energy is heat through the cooling system and 20% is useful work, which means 17.5kW is equivalent to when an ICE is outputting 10kW (13.4hp).
http://www.saldanaracingproducts.com/Cooling System Principles.pdf
I looked around and even a relatively low power 335i (N55 rated at 300hp by BMW) idles at around 20hp. Something like an M5 makes even more power. It might be closer to an ICE's cooling system, rather than the reduce sized one Tesla is using, but I don't see how it would be a challenge to design a cooling system than can handle the heat that 200kW charging might generate.
Dyno Test: BMW 335i and 335is - N54 vs. N55 engine
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To be fair, the battery pack needs to be kept cooler than an ICE, which means you need more efficient cooling, especially with high ambient temperatures.
The Model S battery pack is kept at under 55C, using active cooling. If the ambient temperature is 40C, you only have a 15C temperature difference. If you need to get rid of 17.5 kW, that means you need to have a radiator heating roughly one cubic meter of air from 40 to 55 C every second.
It makes for a big radiator, but it's certainly not impossible.
The Model S battery pack is kept at under 55C, using active cooling. If the ambient temperature is 40C, you only have a 15C temperature difference. If you need to get rid of 17.5 kW, that means you need to have a radiator heating roughly one cubic meter of air from 40 to 55 C every second.
It makes for a big radiator, but it's certainly not impossible.
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