GreenHokie
Member
Because having carbon-sleeved rotors would presumably help address a common complaint that performance minded drivers (like myself) have with the current M3P… it kind of looses its advantage/punch at higher speeds.
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Model 3 Highland Performance/Plaid Speculation [Car announced 04.23.2024]
- Thread starter Daniel L
- Start date
That is my point. If you used the regular Model S drivetrain setup, you lose nothing up top. You don't need the carbon sleeve rotors for that level of speed. The Model S traps much higher and does the quarter mile in mid/high 10s range even without carbon sleeve rotors. I guess if you want to go 200mph, you'd need the Plaid setup but kinda overkill getting a stronger top end to something reasonable like 160mph.
GreenHokie
Member
OK, I see what you are saying. I had previously thought that the regular (non-Plaid) Model S drivetrain setup also included the carbon-sleeved rotors. So, that is why I was thinking that type of rotor would need to be added to the M3P to give it better high speed performance.
I wouldn't complain if they put in the Plaid motors in the Model 3 but I also wouldn't want my M3P to cost over $70k
Give me a upgraded M3P for $60-65k with mid 10s quarter mile times and I would be ecstatic.
GreenHokie
Member
Yeah, me too!I wouldn't complain if they put in the Plaid motors in the Model 3 but I also wouldn't want my M3P to cost over $70k
Give me a upgraded M3P for $60-65k with mid 10s quarter mile times and I would be ecstatic.
Can’t wait to see what Tesla has up their sleeves for the upcoming M3 performance trim. C’mon Tesla, I’m ready to hand over my $60-$80K. Easy money for you….
So much guessing in here.
The modern Model S (including Plaid) uses a 110s battery configuration. This gives a nominal voltage of 401.5V
The Model 3 uses a 96s configuration for 350.4V.
Yeah, the Model S will have more top end. 15% more voltage means a lot even if you change nothing else. There's some non-linearities in here too which mean each volt is worth more than the previous one. Which is why Porsche and others are going to 800V.
As for carbon sleeves on the Plaid- this is because they wanted to flat rate the car to 1000 HP from 0-200 MPH. Their innovative laminate and magnet structure along with carbon winding allows them to reduce the air gap between the rotor and stator. This increases torque at the same voltage. This is not free- this requires more current at the same voltage, but it means you can actually get that current instead of being limited by back EMF. Notice though they needed to go with 3 motors to get that 1000HP. What they are really doing is under-rating each motor at low speeds, so that they can keep the power flat all the way up in software. But it pulls all that off beautifully. I'm sure they very specifically tuned the whole system carefully for this. The Plaid even runs lower gear ratios (14.6K RPM rotor speed @ 162 MPH vs 18,500 for a Model 3 or Model S @ 162 MPH) to trade current and voltage capabilities of the battery.
What do we have in a Model 3 today? Well, we know the sum of the rating of the front and rear motors is already more than the battery can handle. So the battery sets the max current limit for the vehicle. If Tesla didn't care about the battery, the car could already be faster 0-45 MPH. Watts is watts, so you can't fix that with a different motor. All these motors are already 98%+ efficient, so there's no magic there.
So you could put a carbon rotor in a Model 3, and then you'd be able to keep up the power at higher speeds. This would slightly shorten the 45-60 MPH time, but not enough to be a big deal for overall 0-60. And the reality is nobody really cares about 60-100MPH times except racers. Plus, Tesla wants the Plaid in the 2's and the Model 3 in the 3's.
If you really want better 0-60, you need more watts from 15 MPH to 45 MPH. And that's the battery that is limiting that, even today. The motors are not the limit.
Remember- max watts out of a battery is at first order set by how big the battery is. And the Model S has a huge advantage of having 20% more capacity than a Model 3. You can't just re-organize the cells in a model 3 to be higher voltage, because then your allowed peak current is lower. So even a Plaid rotor in a Model 3 would give up much earlier than in a Plaid- but there's a good chance it could be flat rated to 100 MPH.
Oh, then there's the fact that the front and rear motors in a Model 3 aren't even the same architecture and they can't put a Plaid rotor in the front, so that factors in to the overall power curve at high speeds too.
The modern Model S (including Plaid) uses a 110s battery configuration. This gives a nominal voltage of 401.5V
The Model 3 uses a 96s configuration for 350.4V.
Yeah, the Model S will have more top end. 15% more voltage means a lot even if you change nothing else. There's some non-linearities in here too which mean each volt is worth more than the previous one. Which is why Porsche and others are going to 800V.
As for carbon sleeves on the Plaid- this is because they wanted to flat rate the car to 1000 HP from 0-200 MPH. Their innovative laminate and magnet structure along with carbon winding allows them to reduce the air gap between the rotor and stator. This increases torque at the same voltage. This is not free- this requires more current at the same voltage, but it means you can actually get that current instead of being limited by back EMF. Notice though they needed to go with 3 motors to get that 1000HP. What they are really doing is under-rating each motor at low speeds, so that they can keep the power flat all the way up in software. But it pulls all that off beautifully. I'm sure they very specifically tuned the whole system carefully for this. The Plaid even runs lower gear ratios (14.6K RPM rotor speed @ 162 MPH vs 18,500 for a Model 3 or Model S @ 162 MPH) to trade current and voltage capabilities of the battery.
What do we have in a Model 3 today? Well, we know the sum of the rating of the front and rear motors is already more than the battery can handle. So the battery sets the max current limit for the vehicle. If Tesla didn't care about the battery, the car could already be faster 0-45 MPH. Watts is watts, so you can't fix that with a different motor. All these motors are already 98%+ efficient, so there's no magic there.
So you could put a carbon rotor in a Model 3, and then you'd be able to keep up the power at higher speeds. This would slightly shorten the 45-60 MPH time, but not enough to be a big deal for overall 0-60. And the reality is nobody really cares about 60-100MPH times except racers. Plus, Tesla wants the Plaid in the 2's and the Model 3 in the 3's.
If you really want better 0-60, you need more watts from 15 MPH to 45 MPH. And that's the battery that is limiting that, even today. The motors are not the limit.
Remember- max watts out of a battery is at first order set by how big the battery is. And the Model S has a huge advantage of having 20% more capacity than a Model 3. You can't just re-organize the cells in a model 3 to be higher voltage, because then your allowed peak current is lower. So even a Plaid rotor in a Model 3 would give up much earlier than in a Plaid- but there's a good chance it could be flat rated to 100 MPH.
Oh, then there's the fact that the front and rear motors in a Model 3 aren't even the same architecture and they can't put a Plaid rotor in the front, so that factors in to the overall power curve at high speeds too.
GreenHokie
Member
Thanks for the great/detailed response. Sounds like the only way to significantly improve 0-60 times on the M3 is to go with a larger and/or different type of battery (with a higher energy density than the current 2170 cells). The 4680 cells are supposed to provide that, but at the expense of a larger size & weight. Since there is limited room in the M3 chassis to accommodate a larger size battery pack, it is unclear if using 4680 cells in the M3 Performance trim (assuming it is even practical for Tesla) would accomplish much in terms of added performance.
OK. Perhaps I should temper my expectations/hopes for the upcoming M3 Performance model…
If batteries are larger in size and weight, then they don't have higher energy density. Energy density is capacity per volume or per weight (volumetric and gravitational).
But total energy is not the first thing we need. We need peak energy output. There are chemistries that have higher peak output. Ironically, they have LOWER energy densities- because one way you make a battery discharge faster is to make some things inside it bigger or farther apart. But you could just reduce how many of them are in your pack.
This is how the super high performance electric race cars are made. They need to be able to be discharged in only 10-20 minutes. In a Model 3 that would be almost 600 HP for 15 minutes continuous. But they don't need 600 HP average, so they run much smaller capacities overall that can support 500HP peak for a few seconds before the next braking zone.
There is zero way Tesla is putting these batteries in the M3P so that they can advertise lower 0-60 times at the expense of only having a 205 mile EPA range. No matter what trim, the Model 3 is a mass market commuter car first. It's going to be a while before we see a Tesla "M/AMG/STi/N/GR" division that can sell completely bonkers cars that give up all sorts of drive-ability for performance.
Personally super excited to see Porsche's next Boxter which will be all electric.
GreenHokie
Member
While the 4680 battery is indeed physically larger and weighs more than the 2170, I thought the 4680 also has a higher energy density when you normalize/compare the two on an equal mass or equal volume basis. In other words, on a per volume (or per weight) basis, my impression is the 4680 cell still has a higher energy density than the 2170. I guess this is not true, though?
AlanSubie4Life
Efficiency Obsessed Member
Yeah I’d like to see a plot on the Model S power vs. speed. I am sure it is better for the reasons you list but betting it is not like the Plaid.
Are you sure about these statements for lower speed? My understanding is that limits would only occur closer to 45mph, where the power limit is reached.
From say 0-30mph remember the power is way off the peak. So the pack is nowhere near max current.
Of course the voltage of the pack matters at some point. But at low speeds pretty sure it is limited by motor (or inverter).
Maybe I’m wrong, and you can explain how, though.
So if they have a motor that can generate more torque (and take more current and therefore accept higher input power, producing more output power, at lower speeds), it seems like they could swap that in with no pack changes and get a benefit (potentially with some substantial benefits at high speed as well, as you mentioned, due to reduced back EMF).
Just clarifying my disagreement/confusion: this only occurs starting near 45mph. At 5-15mph, where acceleration is at its peak, for example, the draw from the battery is nowhere near peak. Neither motor is anywhere near peak output power.
Someone should post the plot (was on Reddit at some point but too lazy to go find it).
Again, happy to hear/learn how I might be misunderstanding physical limitations here. Very informative posts (I agree with most of it).
Ok, here is the excellent Reddit post (thanks Google; first link). One capture from P3D (ignore the AWD software-limited lines) showing power is way off the peak until it…gets to the peak:
I think there were some other posts too showing battery power draw at the same time and maybe separating front and rear motors. But again…too lazy to look up. They were all linked-to/posted here years ago of course.
EDIT (thanks again Google):
Looks like it was only for the AWD but you get the idea since this shows battery power. Maybe some similar capture also exists for the Performance; don’t quite remember.
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One thing is sure, when the original Model 3 performance was released it could keep up or was faster than the benchmark BMW M3 on a track. Now the M3 has X-drive and more power output than claimed so a drag race now humbles the Model 3P by a good margin! Also the "other" car manufacturers are beating the Model 3 Performance, especially in speeds over 60mph (BMW i4 M50, Kia EV6 GT) in fact a 2022 Model 3 Long Range is faster from 60-70mph and up. Tesla needs to make a true Performance Model 3 with 750ish hp, 0-60 (real time, not the one foot crap) in 2,8 seconds, a much flatter power curve and a battery that keeps the power high down to the 30% mark like the S and X plaid. the way the current model 3P looses its power above 70mph is tragic. My previous 2021 3P with 82kwh Panasonic displayed 445kw discharge power after supercharging and 95%SOC, my current 2022 3P with 75kwh LG shows 400kw discharge power at the same temps and SOC. This is info directly from the BMS using Scan my Tesla.
Lets hope they bring a 750HP, 2,8 0-60, true performance brakes, carbon sleeved rotors, 10 seconds flat (or high 9`s on the quarter) I would order as soon as fu%#&"* possible
Lets hope they bring a 750HP, 2,8 0-60, true performance brakes, carbon sleeved rotors, 10 seconds flat (or high 9`s on the quarter) I would order as soon as fu%#&"* possible
Olle
Active Member
Good points. It's going to be interesting to see what Tesla ends up doing.
While they'll likely not offer much more absolute power if they continue with the "low power" cells of later 3/Y, they could still let the power be available also at higher speeds by counteracting the high speed back EMF during voltage sag. Some ways of doing it:
A. reconfigure the 3/Y packs for the same high voltage as S/X, or even a bit more. Looks like necessary components are already in production; All superchargers can evidently deliver 450V and the new ones even more. The onboard chargers and inverters from S/X handle up to 462V battery voltage and in Munro's teardowns of S and Y, these appear to be drop in replacements between S/X ->3/Y.
or
B. wind the motors for lower voltage.
or
C. configure the inverters for voltage boost. probably the the least attractive option, since it would require a new PCB, larger inductors and reduced efficiency.
What a weird thing to quote out of context out of the whole paragraph, which was about energy needs for race cars....
But I promise you that no Tesla battery can be discharged at 4C for 15 minutes. Short term, yes. But the cooling is nowhere near good enough to deal with it for a whole discharge cycle.
Handling 100kW of heat while maintaining only a 30C or so delta to air is no simple task, nor one a Tesla needs to be designed for.
The answer is nothing. Because the whole point is to get great 0-60 times out of a high volume commuter car. Not to build a low volume sports car.
All of your options reduce efficiency. If you re-arrange cells for higher series voltage, you increase the internal resistance of the battery and increase IR losses. This isn't an issue with the 100kW packs that maintain as many parallel cells and add series strings, but there is a reason the Model 3 doesn't do that.
You can't just "wind motors for lower voltage" without tradeoffs. If this worked, Tesla would have done this 8 years ago when designing the Model 3 motors.
While you could theoretically build a boost converter, the efficiency drops are large, and a 400kW DC-DC is not small or cheap. You realize a normal inverter uses the motor itself as the inductance and hardly has any internal inductance or capacitance?
We're all discussing this as if Tesla has to make a faster Model 3, as if their goal is to compete with sports cars, or even BMW M3's. It's not. The performance is a side effect of being electric, not the goal. They absolutely cannot afford to mess with the efficiency millions of Model 3's just so a few of us that care can go slightly quicker.
Tesla's investment in sports cars does exist. It's called the roadster.
Completely different cars and markets. What's your question? The M3Plaid doesn't exist so there is no pricing and Highland pricing doesn't exist in the USA yet.
