How much horsepower in the P3D "at the crank?"

[Dolemite]

...or whatever we're calling it. Typically, ICE cars are quoted at the crank. I'm not sure whether there's a common language for EVs yet.

MountainPass is publishing figures at the wheel - I don't believe they're doing any kind of adjustment for drivetrain losses? Please correct me if I'm wrong.

Brooks from DragTimes is simply measuring the power output from the battery w/ this app? Or something. See @ 7:50:

So I've heard numbers from 500 hp all the way up to 580 hp. If quoting figures the same way you would an ICE car, which is more correct?

 

[Saghost]

...or whatever we're calling it. Typically, ICE cars are quoted at the crank. I'm not sure whether there's a common language for EVs yet.

MountainPass is publishing figures at the wheel - I don't believe they're doing any kind of adjustment for drivetrain losses? Please correct me if I'm wrong.

Brooks from DragTimes is simply measuring the power output from the battery w/ this app? See @ 7:50:

So I've heard numbers from 500 hp all the way up to 580 hp. If quoting figures the same way you would an ICE car, which is more correct?

Like the old Rolls Royce quote; "Sufficient."

 

[MXLRplus]

EVs don't have a lot of drivetrain loses compared to ICE powertrains.
It's a light rotating mass, single reduction gear, and 4 constant velocity or U-joints. There is no hypoid gear limited slip diff, or driveshaft or accessories. Accessories are not traction motor driven.
AWD cars are problematic, especially EVs since when both motors are at 100%, it puts a bigger sag on the voltage than if you do each end and add them.

 

[MXLRplus]

For racing purposes, you can use a trap speed measured with beams or a radar gun, or a very fast datalogger.
As you increase power, your MPH through the beams climbs. It's actually a pretty stable way to do tuning.

 

[DrDabbles]

EVs don't have a lot of drivetrain loses compared to ICE powertrains.
It's a light rotating mass, single reduction gear, and 4 constant velocity or U-joints. There is no hypoid gear limited slip diff, or driveshaft or accessories. Accessories are not traction motor driven.
AWD cars are problematic, especially EVs since when both motors are at 100%, it puts a bigger sag on the voltage than if you do each end and add them.

Yeah, to further expand on this, the reason you hear "at the crank" versus "at the wheels" with an ICE vehicle is because everything between the engine's output shaft and the wheels robs the vehicle of power. The transmission and any AWD differentials are especially bad at this, and an ICE vehicle can easily lose between 15-20% of the power from the engine.

As MXLRplus says, in an EV we don't have a lot of these losses. And, in fact, the step down gearing from the motor to the axles means torque is likely significantly increased rather than decreased. So measuring at the motor output shaft really makes no sense.

But, perhaps to answer your question better, the motor's maximum output is limited by the power you can put through its coils. So for Model 3 motors you could probably assume 400kW+ maximum per motor before doing some kind of damage. Somewhere near 540HP per motor would be my rough guess. Tesla limits the motor power well below these levels, though, and regardless of the motor's technical capabilities the battery pack will be your limiting factor. That's somewhere around 484kW max discharge (1200 Amps)

 

[Saghost]

Yeah, to further expand on this, the reason you hear "at the crank" versus "at the wheels" with an ICE vehicle is because everything between the engine's output shaft and the wheels robs the vehicle of power. The transmission and any AWD differentials are especially bad at this, and an ICE vehicle can easily lose between 15-20% of the power from the engine.

As MXLRplus says, in an EV we don't have a lot of these losses. And, in fact, the step down gearing from the motor to the axles means torque is likely significantly increased rather than decreased. So measuring at the motor output shaft really makes no sense.

But, perhaps to answer your question better, the motor's maximum output is limited by the power you can put through its coils. So for Model 3 motors you could probably assume 400kW+ maximum per motor before doing some kind of damage. Somewhere near 540HP per motor would be my rough guess. Tesla limits the motor power well below these levels, though, and regardless of the motor's technical capabilities the battery pack will be your limiting factor. That's somewhere around 484kW max discharge (1200 Amps)

I’m curious what you used to develop your estimate of the maximum power that the model 3 motors can take.

With radically different designs, I don’t see why the limits on the two motors would be the same.

You also left one of the important limiting components out. Tesla is using a couple of variations of AC motor on the car. They have to be fed synthesized 3 phase AC waveforms, which are generated by rather expensive and complicated blocks of high power transistors - the drive inverters.

The current limits on those transistors are another limit on vehicle power and torque output. It’s not obvious whether the motor or inverter limit hits first, and aside from component bench testing or getting full detailed specifications I don’t know how you can figure that out.

 

[Dolemite]

Yeah I understand all that... I just need to know what to say for penis measuring purposes. So what are the numbers that Brooks from DragTimes is quoting?

 

[Black306]

I’m curious what you used to develop your estimate of the maximum power that the model 3 motors can take.

With radically different designs, I don’t see why the limits on the two motors would be the same.

You also left one of the important limiting components out. Tesla is using a couple of variations of AC motor on the car. They have to be fed synthesized 3 phase AC waveforms, which are generated by rather expensive and complicated blocks of high power transistors - the drive inverters.

The current limits on those transistors are another limit on vehicle power and torque output. It’s not obvious whether the motor or inverter limit hits first, and aside from component bench testing or getting full detailed specifications I don’t know how you can figure that out.

First off, I completely agree; there is no way for us to know for sure what the maximum output of the system (ie motors, inverters, batteries, etc.) is capable of without proper equipment or Tesla disclosing more information.

My estimate using nominal battery voltage and Tesla’s own published maximum current ratings, the output for the motors is approximately 600hp combined (Performance model).

Model 3 performance degradation w/ battery degradation?

Again, this is over simplified, not taking all variables into account, and needs to believe the whole system was designed with a similar output target.

That said, we may not know what is the maximum power but I believe that the car is capable of more power than what is currently available.

 

[MXLRplus]

Yeah I understand all that... I just need to know what to say for penis measuring purposes. So what are the numbers that Brooks from DragTimes is quoting?

It doesn't take as much 'brochure HP' for an EV to take an ICE car.
It comes down to average RWTQ going down the strip. ICE engines need to build RPM to get maximum power, EVs do not.

 

[user212_nr]

Tesla Model 3 Performance AWD Technical Specs, Dimensions

456 hp
471 lb.ft torque
1847 kg weight

Ford F-150 2.7L EcoBoost V6 4x2 6.5 ft. SuperCrew Technical Specs, Dimensions

Ford F-150
385 hp (287 kw)
387 lb.ft torque
2087 weight

If it had a tow hook it should tow the F-150 with no trouble in a "tug of war" match.

 

[DrDabbles]

I’m curious what you used to develop your estimate of the maximum power that the model 3 motors can take

Take the power of each motor, and presume Tesla has an added pad for safety. Keeping in mind also that the Model 3 motors were used in the Semi, we know that the Semi is capable of just under 2kW output, and that the Semi had 4 motors. So that would indicate something just below 500kW per motor, which is right around 25% higher than the number I gave.

With radically different designs, I don’t see why the limits on the two motors would be the same.

They won't be the same. We know they aren't the same.

You also left one of the important limiting components out. Tesla is using a couple of variations of AC motor on the car.

For the sake of simplicity, I didn't get into the details. There was no need to do so, given the question and my answer.

They have to be fed synthesized 3 phase AC waveforms, which are generated by rather expensive and complicated blocks of high power transistors - the drive inverters.

Yeah, I mean, the SIC IGBTs used in the inverters can likely handle more power than the coils in the motors. And really, the bus bars before the inverter, the cable from the penthouse to the motors, and the fuse will blow before those components. These cars aren't designed by nobodies, the engineers understood the requirement of protection at every level. Again, describing how high frequency switching works isn't necessary to answer the original question.

The current limits on those transistors are another limit on vehicle power and torque output. It’s not obvious whether the motor or inverter limit hits first, and aside from component bench testing or getting full detailed specifications I don’t know how you can figure that out.

We don't need to bench test, we can make general assumptions given similar components on the market. You can select IGBTs that are similar to what Tesla selected, you can look physically at the fuses they've selected, and you can use extremely well known calculations based on winding count in a motor.

...or you can add a margin on top of the performance numbers we already know, assuming Tesla aren't fools, and use that as a general answer. Which gave me ~400kW, when we know Tesla is planning on just below 500kW in the Semi.

 

[Zcd1]

...So I've heard numbers from 500 hp all the way up to 580 hp. If quoting figures the same way you would an ICE car, which is more correct?

Any number you'd care to choose in between those 2 should would be accurate enough...

 

[user212_nr]

Any number you'd care to choose in between those 2 should would be accurate enough...

Tesla has stopped quoting horsepower because it is misleading. Peak horsepower is a number that can be reliably measured and isn't subject to much interpretation.

For example, the F-150 weighs the same as the Tesla, or similar from what I found, and has similar HP and torque. Yet it takes 17 seconds 0-60. Some of that is due to aerodynamics (bad car to compare), but the rest is due to the petrol engine being unable to reliably deliver the peak horsepower + torque over that distance.

But HP itself is a definitive number. You might say it has "the same effective HP" as a car with 580 HP. The Audio S8 has a 0-60 time of 3.2 seconds and it has 597 HP. It also costs over 100k.

Better just to stick to 0-60 times to avoid redefining scientific concepts like HP.

Audi S8 - Wikipedia
0-60 Times and Quarter Mile Times - Updated 2020 - 0-60 Specs

 

[Zcd1]

Tesla has stopped quoting horsepower because it is misleading. Peak horsepower is a number that can be reliably measured and isn't subject to much interpretation.

For example, the F-150 weighs the same as the Tesla, or similar from what I found, and has similar HP and torque. Yet it takes 17 seconds 0-60. Some of that is due to aerodynamics (bad car to compare), but the rest is due to the petrol engine being unable to reliably deliver the peak horsepower + torque over that distance.

But HP itself is a definitive number. You might say it has "the same effective HP" as a car with 580 HP. The Audio S8 has a 0-60 time of 3.2 seconds and it has 597 HP. It also costs over 100k.

Better just to stick to 0-60 times to avoid redefining scientific concepts like HP.

Audi S8 - Wikipedia
0-60 Times and Quarter Mile Times - Updated 2020 - 0-60 Specs

Not trying to be contrary, but everything you wrote can be inferred (and was indeed intended) via the single sentence I wrote...

 

[user212_nr]

Not trying to be contrary, but everything you wrote can be inferred (and was indeed intended) via the single sentence I wrote...

Yes, I could infer it, but I'm not sure about others. Quoting 500-581 horsepower without a disclaimer is technically wrong.

 

[PhaseWhite]

Yeah I understand all that... I just need to know what to say for penis measuring purposes. So what are the numbers that Brooks from DragTimes is quoting?

The car measures power output from the battery, I think comparing that to crank HP is reasonable because the battery is where the power is coming from, where as in an ICE car the power is coming from the engine.

I dug this one up recently after the 5% boost in November 2019 was released which shows peak power at around 430KW / 576HP
Model 3 AWD Power vs. Speed (fw 2019.8.5)

Hopefully that's big enough for you to compare sizes with your friends.

Tesla Model 3 Performance AWD Technical Specs, Dimensions
456 hp
471 lb.ft torque
1847 kg weight

Tesla's numbers haven't changed since the car was released in 2018, despite the various software updates that boosted peak power so they can't be trusted at all.

 

[user212_nr]

The car measures power output from the battery, I think comparing that to crank HP is reasonable because the battery is where the power is coming from, where as in an ICE car the power is coming from the engine.

I dug this one up recently after the 5% boost in November 2019 was released which shows peak power at around 430KW / 576HP
Model 3 AWD Power vs. Speed (fw 2019.8.5)

I just linked what I could find - it was remarkably difficult to find a number quoted in HP.

To use the energy as HP, you would need to know what is the efficiency of the motors. If the efficiency was 80%, then that number would be 576*0.8 = 460. At 90% efficiency, 518 HP.

Do the motors become less efficient as the power increases?

https://www.quora.com/Do-Tesla-cars-really-have-an-efficiency-above-85?share=1

 

[Knightshade]

I just linked what I could find - it was remarkably difficult to find a number quoted in HP.

To use the energy as HP, you would need to know what is the efficiency of the motors.

Nope.

That's the point of "at the crank"

it's how much power is coming from the source... (the engine in an ICE, the battery in a BEV)


You'd need to know the efficiency of the motors if you want to guess "at the wheel" power though... (plus you'd need to know any other drivetrain losses though they'd be quite low on a single-speed EV)


Anyway, the #s I've got using the canbus data from other sources (WUGZ has a lot on this) is:

P3 (current)- 580hp
P3 (1st 5% bump)-549hp
P3 (no bumps) - 529 hp

AWD+ (boosted)- 497 hp
AWD (2nd 5% bump)- 447 hp
AWD (1st 5% bump)- 414 hp
AWD (no bumps)- 380 hp

 

[user212_nr]

Nope.

That's the point of "at the crank"

it's how much power is coming from the source... (the engine in an ICE, the battery in a BEV)

From what I understand,

HP "at the wheel" == hook up a dyno to the wheel
HP "at the crank" == hook up a dyno to the crankshaft (the first rotational output of the engine)

That is, to measure the output of the motor before the drivetrain (transmission, axel, wheel hub, etc).

To measure the input of the motor and not its output would be like measuring the amount of gasoline used.

 

[DrDabbles]

To measure the input of the motor and not its output would be like measuring the amount of gasoline used.

Those are valuable measurements with an ICE vehicle. Measuring the engine output at the crank is valuable, because it tells you the capability of the engine itself before any losses. Measuring the fuel used is valuable for efficiency measurements. But they are dissimilar measurements.