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Petition Tesla to make the Model 3 Performance 0-60 <3s
- Thread starter Sutton 3P
- Start date
Dan203
Active Member
Is there a physical difference between the motors/batteries in the 3 vs the S that would prevent them from pushing it to <3s? Or is this all just software? Could they add a ludicrous mode to the 3 that requires the batteries to be warmed up and can only be used in short stints like they did with the S?
WilliamG
Hinge Fanatic
It's not that simple. It's absolutely possible they can improve the 0-60. The question is what impact that has to the mechanical and electrical systems? Launch control shouldn't have any appreciable impact to durability, so that's an option. It won't do all that much, but it is basically free and presumably easy to do. I don't know why they decided against that.
The motor can briefly handle more power, I don't doubt that. The issue is the power below the peak is limited by the max phase current of the power electronics, and that most likely is already at its limit. If they really bin the inverters, this means they need to do this to be confident they can handle the power. They run multiple packages per side of each phase. If they have extremely minor differences, they won't share current evenly and this significantly limits the power the string can handle. And this is really only to tolerate a one time event. If you need it to sustain frequent intermittent high peaks, this means thermal cycling. Thermal cycling tends to cause differential expansion, which fatigues components internally over time. The more this can be reduced, the higher likelihood devices have to last longer. So this would mean long term reliability, assuming a good design otherwise, is limited by the thermal deltas its exposed to. Higher peak currents will generate considerably larger deltas, this is most often non linear, especially as you approach design limits of the packages. This is an oversimplification, and doesn't take into account the issues with the rest of the driveline. The summary is, higher power will adversely impact long term reliability. How much so, only Tesla knows. But its very likely a safe assumption they are running the hardware as hard as it was designed to tolerate long term. This is not witchcraft, it is well established practice at this point. Given the exceptional hardware design, its safe to assume they had a good team on the power electronics that understand the limits. There is no reason to suspect they would leave a lot on the table when the success of the company very much relies on the success of this vehicle.
Given very limited statistics, yes. Now that they have far better statistics they can reconsider this reliability/performance trade off. One thing that would seem obvious is to increase the acceleration at low speeds. With the performance package tires they could go close to 1.2g. This would not seem to result in the thermal issues you mention, as the total power output at low speeds is still relatively low.
The thermal mass of the output devices is very low, any load will cause some non zero heating and differential expansion. The output devices in the inverter are actually at highest load at lower speeds and full throttle. This is why I went into more detail on that, that's the primary limit below ~50MPH. Its unlikely it can be increased, I don't see what they could have really learned from the fleet over time with that one. It's very easy to bench test and determine a sensible design limit. The difficulty is the uncertainty, given the manufacturing variations. Binning this helps weed out the outliers, but you still need overhead to have some degree of confidence. And the mitigation of this uncertainty is highly dependent on how thoroughly you test, and how much scrap you're willing to tolerate. The peak power increase didn't appear to impact the phase current, so it probably was more of a concern for the cells or the way the bricks are assembled. I don't see why they would be concerned with 5% more power on the reduction box, axles, or even the motor given the thermal probe on the windings. But this logic would mean both the inverter and battery are at sensible limits.
Excuse my ignorance, but why would that be? We know acceleration is roughly constant up to 60mph and physics tells us the required power to maintain constant acceleration increases exponentially with speed. So why would inverters be delivering maximum power at low speeds?
most people don't consider the substantial impact a great set of tires can do for launch times..
The inverter is acting as a buck converter. At lower speeds the motor is willing to take oodles of power, and as rotor speed increases its reluctance to accept power increases. So this means if you don't restrict it, the motor would take absurd power at low speeds. The inverter needs to limit the output current to save itself, so the limit in the majority of cases at low speed is the inverters phase current limit. Be aware, since at low speeds the voltage is going to be lower, the output current is not the same as the input current. What we really care about is the acceleration, primarily caused by the output power. But the inverter primarily cares about its output current. The expected profile for this is basically going to be a flat line on the programmed limit, until it hits another limit, probably the max battery current.The inverter isn't super concerned about the power, its effectively switching current. This is a reason why ~400V systems are commonly used. Most of the best output devices are available in this voltage range, which is a positive feedback loop for more products to run on this voltage, which creates further demand. I'm probably getting totally off topic.
At low speeds with the pedal to the floor, the inverter is doing a lot more switching on and off to hold current below design limits. And its switching into a load thats willing to take a ton of jam. This is the harshest environment it operates in. As speed increases, the motors load gets softer, duty cycles increase, and phase current drops. For the Model 3, with its current gearing, the transition appears to happen around 50MPH. So getting a better launch is primarily a function of the inverter. Above ~50, the limit is either the battery, motor, or some part of the mechanical system. Most likely the battery.
You like the 4 screen tron interior?
It'll be interesting if Tesla ever posts a Nordschleife time for the 3P. And then there is the roadster, which by price is more of a competitor to the Taycan than the S. Clearly Tesla can make a great handling car, and I can't imagine that the roadster won't be able to keep up on a race track.
I don't think it's possible, but would like the option if it were. Make it a paid option and bring in some revenue.
If the P3D can beat an M3 then the roadster will no doubt beat the taycan.
Knightshade
Well-Known Member
I agree it's a lot better comparison to it than the S or 3 really are... and I'd expect it'd beat the Porsche up pretty badly on a track too...but there's still not even a production date for the Roadster... at this point it seems like it's behind the Y, and the pickup, and maybe the Semi?
And runs another 50-100k more too than the Taycan seems to (depending on optioning).
Knightshade
Well-Known Member
Swampgator
Active Member
Dan203
Active Member
That's like saying the BMW M3 canabalizes 7 series sales. They're two different cars aimed at two different types of buyers. Tesla may be losing S sales to 3 sales now, but that's because before the 3 existed people were overextending themselves to get an S because it was the only viable EV on the market. Very few people who are in the market for a 3 are willing to spend an extra $40k on an S just to get a 1s faster 0-60. Many would however be willing to spend an extra $5-10K on an upgrade to the 3 that would give them that same 1s lower 0-60.
Are you sure about this - isn't the power dissipated proportional to the energy stored in the capacitor (ie. \propto V^2)?
If this was the case, wouldn't lower current configurations like AWD non-P dissipate even more power and thus need higher power inverters?
I think that was the point, and thus the model 3 with performance package can in principle accelerate much faster.
