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Tesla blog post: AWD Motor Power and Torque Specifications

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LOL. The issue here is that Tesla flat out lied about the power the car made. It makes nothing close to 691HP. You are trying to justify it by muddying the waters with things that are irrelevant. The car will not make anywhere close to the power advertised with a battery at 100%. That is a fact.

So in your world, people should take it easy on Tesla because there are people out to get them etc., so it's okay for Tesla to lie in order to survive? Awesome logic.

Lied implies intent. The two motors added together under ideal test conditions do make 691 motor hp. Tesla never said 691 hp at shaft or wheels. Yes, it was vague and misleading anyway.
 
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LOL. The issue here is that Tesla flat out lied about the power the car made. It makes nothing close to 691HP. You are trying to justify it by muddying the waters with things that are irrelevant. The car will not make anywhere close to the power advertised with a battery at 100%. That is a fact.

So in your world, people should take it easy on Tesla because there are people out to get them etc., so it's okay for Tesla to lie in order to survive? Awesome logic.

Thanks. I agree it is awesome logic.


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Fuzzy logic is a form of many-valued logic in which the truth values of variables may be any real number between 0 and 1. By contrast, in Boolean logic, the truth values of variables may only be 0 or 1. Fuzzy logic has been extended to handle the concept of partial truth, where the truth value may range between completely true and completely false.[SUP][1][/SUP] Furthermore, whenlinguistic variables are used, these degrees may be managed by specific functions

Classical logic only permits propositions having a value of truth or falsity. The notion of whether 1+1=2 is an absolute, immutable and mathematical truth. However, there exist certain propositions with variable answers, such as asking various people to identify a colour. The notion of truth doesn't fall by the wayside, but rather on a means of representing and reasoning over partial knowledge when afforded, by aggregating all possible outcomes into a dimensional spectrum.
Both degrees of truth and probabilities range between 0 and 1 and hence may seem similar at first. For example, let a 100 ml glass contain 30 ml of water. Then we may consider two concepts: empty and full. The meaning of each of them can be represented by a certain fuzzy set. Then one might define the glass as being 0.7 empty and 0.3 full. Note that the concept of emptiness would be subjective and thus would depend on the observer or designer. Another designer might, equally well, design a set membership function where the glass would be considered full for all values down to 50 ml. It is essential to realize that fuzzy logic uses truth degrees as a mathematical model of the vagueness phenomenon while probability is a mathematical model of ignorance.
 
delivering 1MW of power to the motors
The whole question is about "for how long" and you completely missed it.
Take 1F 400V capacitor that is "fully" charged and short circuit it via thin (0.8 mm[SUP]2[/SUP]) 1m long copper wire (0.021 ohm resistance). Voila, +7MW "instant" power that wont even heat up the wire but that does not change the fact that there was short ~7MW burst.

I was hoping to hear more ...

instantly
There is no such thing as "instantly". *Everything* needs some time to happen. And if/when times are really short, really funny things can also happen. Power by itself means nothing, it needs some temporal quantification to have real meaning.
People are used to some numbers without much understanding what they mean.

Would you be happy with 550kW for 0.1 seconds?
 
Lied implies intent. The two motors added together under ideal test conditions do make 691 motor hp. Tesla never said 691 hp at stay or wheels. Yes, it was vague and misleading anyway.
We have been over this before. 691HP will sell more high margin cars than 555HP. All of their other offerings make the power they state, even though the capability of the motor is higher. How can anyone say that this was not deliberate?

I would bet that there is no way that most P85 owners that traded up would have taken the loss that they did on their cars, if the power difference was only 100HP.
 
Lied implies intent. The two motors added together under ideal test conditions do make 691 motor hp. Tesla never said 691 hp at stay or wheels. Yes, it was vague and misleading anyway.

When I buy a *motor* from Tesla, this is the rating I'm going to want to see.

When I buy a *car* the numbers they advertise should reflect what the *car* does at least somewhere on the power train. Therefore the methodology they used is flat out wrong and a flat out lie since they know the car can not make this power, yet it was touted everywhere as the headline of the car.

Give me a break.

I feel a little guilty about leaving sorka and the few others in the trenches to fend off crap like this on their own.
 
This post is yet another obfuscation attempt that might work on people who don't know what you're talking about, just like JB's post. You add no relevant information to the topic and are simply grabbing two small portions of my in-depth post in an attempt to discredit the information I provided by throwing out things that have no bearing on the topic. As mentioned in my post which disappeared, Tesla should definitely hire people like you to support their position on this matter because this post is definitely a prime example of people trying to bury the reality of the situation, just like they attempted to do.
I think what I point out is the core point of my analogy that you responded to originally. The crux of the issue here is whether horsepower standards must reflect the system as a whole, so I gave an example where it doesn't: SAE Gross hp. That horsepower standard characterized the engine, not the system as a whole. I hope we have agreement with that. I see this as an exact parallel with "motor power" in this case (which characterized the motor/inverter and not the system). And it also happens that the end effect in terms of percentage is very similar.

This is laughable. Really? My analogy works perfectly fine, where your attempt to explain it away definitely does not. I mean, sure a bench power supply puts out electricity... just like a nitrous oxide tank puts out a combustible fuel. The "engine" is unchanged in both cases, and can run from whatever fuel source you feed it if it is fed correctly. In an ICE this is something that explodes. (I've personally run an old cabureted ICE car from a hydrogen and oxygen mixture with zero modifications to the stock engine.) In the P85D this is a high voltage high current DC source (assuming you're allowing the inverter, which is physically welded to the motor, to be part of the engine in this case... or have we stooped low enough to be arguing the rating the AC side only?). What you're saying is that Tesla is allowed to choose any fuel that they want in an effort to inflate the actual advertised performance numbers of *the car*, regardless of the performance of the actual fuel used in the real world (the battery's power output). By your logic, Audi, BMW, etc should be allowed to test their engines and advertise power numbers using any fuel they can come up with that gets the best numbers (nitrous oxide is the first to come to mind, but I'm sure there is probably something better) and we should be OK with that.
I see the fuel analogy as kind of a side point and a very imperfect one. In your original example, you said diesel and gasoline. If you put diesel fuel in a gasoline engine and vise versa, will likely not even work (and will damage the engine). An ICE can tolerate some fuels, but it will run completely differently even if you put the fuel with the same equivalent amount of energy. It is very hard to match up such an analogy with a DC power source, where what matters is the voltage and current (not the characteristics of the DC supply other than that).

I've been in arguments over ECE R85, the power rating standard Tesla uses in the EU, which doesn't specify that the motors must be tested with the DC source as installed in the car (while it does for the accessories attached to the drivetrain). I have been waiting to be corrected on this point, but it appears to be 100% true, esp. after Straubel's statements.

In fact, a poster pointed out a line on page 9 that seems to suggest that the standard does not expect the manufacturer to use the factory installed battery during test:
"Note: If the battery limits the maximum 30 minutes power, the maximum 30 minutes power of an electric vehicle can be less than the maximum 30 minutes power of the drive train of the vehicle according to this test."
http://www.unece.org/fileadmin/DAM/trans/main/wp29/wp29regs/2013/R085r1e.pdf

That statement seems to match with Straubel's statements:
"Since the battery electric horsepower rating varies it is not a precise number to use for specifying the physical capability of an EV. The motor shaft horsepower, when operating alone, is a more consistent rating. In fact, it is only this (single or combined) motor shaft horsepower rating that is legally required to be posted in the European Union."

Unfortunately for you, this speaks volumes to your lack of actual knowledge of the subject, or that maybe you do understand and are using that understanding to obfuscate the situation even more. Let's break it down.

Just like Tesla, you've pulled a switcheroo without explaining yourself. You've switched your own defense of "motor power" to now include the limitations of the car, since it suites your obfuscation in this case. The *car* will certainly artificially limit the amount of power flowing to the motors until it is not traction limited (the ~40 mph area you mention). The *motors* have no such limitation and would happily accept their full rated power regardless of traction, if that power were available. Any limitations to the power flowing into the motor are artificially created by software. So, I stand by pointing out the fact that the sentence from the blog post, "With the P85D the combined motor shaft power can often exceed the battery electrical horsepower available," is a lie (misleading at best) since the combined motor shaft power (a static rating) is never less than the battery power available. I'm not sure how math works over there in California, but as far as I know 415 kW or less is always less than 515 kW, not "often" less.
I have seen the claim by others that electric motors can always output their peak power in the low rpm ranges, but I don't believe this to be true. Horsepower is a factor of torque and rpm. At low rpms, the peak torque of the motor limits the amount of power it can output. And given the torque is a direct function of input current, which is in turn limited due to inverter and the current limit of the motor windings, it would be impossible for the motor to output peak power at the lower rpms.

This is more readily shown with a power curve of a car that is not traction nor battery limited (the Roadster; if you doubt that, you can look up a Leaf power curve too):
torque.png


Here is the power curve of a UQM Powerphase motor (not installed in a car):
image008.269191236_std.png


In both cases, the peak power is not reached until later in the power band and it does not appear to have anything to do with traction, but rather because the motor is hitting its maximum torque limits at the lower rpms (the graphs seem to make that clear).

As for SAE ratings, there are pretty good reasons why for the past 40+ years car manufacturers have advertised the actual horsepower ratings of their vehicles. What you're saying is that Tesla should be allowed to ignore that and get away with it.
Look at the history. Car manufacturers did not switch to net power ratings in the 1970s because they wanted to be more honest. They switched because during the fuel crisis, it was bad to be seen as making a car with irresponsible amounts of power (it was the time when CAFE fuel economy standards were introduced). Switching to net power gave them a convenient way to adjust their advertised power numbers down without having to reduce it in real world use.
 
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The whole question is about "for how long" and you completely missed it.
Take 1F 400V capacitor that is "fully" charged and short circuit it via thin (0.8 mm[SUP]2[/SUP]) 1m long copper wire (0.021 ohm resistance). Voila, +7MW "instant" power that wont even heat up the wire but that does not change the fact that there was short ~7MW burst.


I was hoping to hear more ...


There is no such thing as "instantly". *Everything* needs some time to happen. And if/when times are really short, really funny things can also happen. Power by itself means nothing, it needs some temporal quantification to have real meaning.
People are used to some numbers without much understanding what they mean.

So now you're trying to tell me that I don't understand what the numbers mean. Come on really? This is getting super old. For the record the Model S does not have a 1F 400V capacitor in the drive unit... the fact that you would even imply that it does shows your ignorance.

Would you be happy with 550kW for 0.1 seconds?

Happy? Not sure happy is the word I'd use. Less cheated? Yes, I would.
 
the fact that you would even imply that it does shows your ignorance.
Sorry, I was sure I was clear enough that I am not speaking of any real product, but mere academic example. You failing to notice it shows what?

There are dynamometers capable of measuring thousands of HP and Torque.
Yes, there are.
What would such dynamometers say about a motor that outputs 1000 HP for a second and then 0 HP for another second and again 1000HP for a second and yet again 0 HP for a second etc?
Will they jump between 1000 and 0 or between 800 and 200 or between 600 and 400 or will they simply show 500? Or 1000? It is called sensitivity.
All dynamometers sample the output in some intervals and average the result.
What if those seconds turn into miliseconds?

How long must a dynamometer run last for results to be representative? You run it for 2 hours and it will show 0 HP for Model Sbecause battery will run out.
You run it for 20 minutes and it may show 60kW because motor/pem will overheat.
You run it for 1 minute and it may show ~300kW or something?
You run it for a second and it wont show anything because it needs more time to come up with a result.

What is the right time?
 
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It is not lying if it is halfway true! Haha

The sad reality is consumers have been programmed to buy cars and brag about cars using one number: peak hp

Imagine if Tesla came out with a P90Q with four motors, but it had the exact same battery hp as the P90D. They would be stupid to advertise it using battery hp. People need to stop being naive. Tesla would be stupid to be "honest" in this situation.

Should they also be forced to state the battery hp at 1% capacity? Or maybe the battery hp at the -20C. Or maybe the battery hp when it is in overtemp mode. No motor power is the best correlation to cost. A P85DM could be made with one rear motor and have the exact same battery hp, but use a Mechanical gearbox instead of two motors. Under your proposed system from the average customer perspective they would be the same car. When porsche makes an awd 911 they don't add another motor to the front. Is it also fair the the 918 hybrid gets to state combined system hp even though they use a tiny 6.6kw battery pack that will be quickly depleted. We are in a new world but most people are still living in the past.

I think we would have at least been satisfied if they'd stated the actual power at 100% charge under ideal conditions which in this case is 555 hp. The power drops considerably as charge declines(something the other Model S variants don't do until they get to much lower SOCs than the P85D does). Bu they didn't even do that. They took the power that each motor can and does make on their own and added the two numbers even though both motors never make that added up number together.

Should give Tesla a discount for the fact that the power band is wider than an ICE? Perhaps. It certainly is the main reason why the P85D can do 0-60 so fast as that wide power band provides a lot of power down at low RPMS (torque) compared to an ICE but once you're at freeway speeds, modern sport sedans with their 8 speed transmissions keep the ICE very near their peak power as the run through the gears while accelerating that wide power band advantage *mostly* disappears compared to an ICE. I say mostly because an ICE that make 560 hp at it's peak will only make maybe 540 at the gear shift, head back up to 560 as the gear hits the middle and then back down to 540 on the other side before the next upshift(this is just an example and will vary from ICE to ICE depending on the characteristics of it's power band). So the ICEs is going to average 545 through the gear shifts rather than it's peak of 560. We can give Tesla a small discount for that which is why I would have been fine with power rated at the battery rather than further downstream at the motor shafts where it would be less due to conversion losses.


Would there still be those that complain had Tesla stated true hp but only under ideal conditions? Yes, I'm sure there would have been some, but it would have been a very small number compared to what it is now. The main complaint at that point would be what the original 691 * thread was all about and that is declining power as the battery charge goes down. Even if the P85D produced 525KW at the battery, they still should have said that the car will lose power as the charge goes down. Most consumers aren't going to understand this and in fact many previous Tesla owners didn't realize this because their previous S85 or P85 didn't start losing power until a much lower SOC. The S85 is full power all the way below 40% while the P85 is full power all the way down to 60%. The P85D starts dropping immediately in the normal daily driving range.
 
Sorry, I was sure I was clear enough that I am not speaking of any real product, but mere academic example. You failing to notice it shows what?


Yes, there are.
What would such dynamometers say about a motor that outputs 1000 HP for a second and then 0 HP for another second and again 1000HP for a second and yet again 0 HP for a second etc?
Will they jump between 1000 and 0 or between 800 and 200 or between 600 and 400 or will they simply show 500? Or 1000? It is called sensitivity.
All dynamometers sample the output in some intervals and average the result.
What if those seconds turn into miliseconds?

How long must a dynamometer run last for results to be representative? You run it for 2 hours and it will show 0 HP for Model Sbecause battery will run out.
You run it for 20 minutes and it may show 60kW because motor/pem will overheat.
You run it for 1 minute and it may show ~300kW or something?
You run it for a second and it wont show anything because it needs more time to come up with a result.

What is the right time?

Not sure what the above rambling is about but Elon claims the P85D makes the most hp at 90% SOC. Charge the car to 90%, strap it to a dyno and measure the hp. Compensate for drive line loss and you have the HP of the p85d. That's it. You're done...
 
And they are lying from the start and for all their models.

You want proof? Here:


Tesla Model S can only sustain 69 kW of continuous power and even that power disappears after an hour or so.
Any higher number than 69kW can only be output for some shorter time.

It all boils down to dash display. It is to damn slow to show short bursts of X kW.
How high can X go? Depends entirely on dash refresh time.

There is some energy in those wires and capacitors that is 'spent' in microseconds after applying it to the motors.
Even if it is just 2,5 mAs, if it is spent in a microseconds, that results in 1MW of power burst.

Is that not a long enough time to be relevant? What is? A milisecond? A tenth of a second? A second? Ten seconds?

There is no such standard. I agree it would be useful, say 10 second window sounds good.
But than again in a car with 3s 0-60 time those 10 seconds may be to long to distinguish cars that can do 100kW for 10s from those that can do 200kW for 6s and only 50kW after that.
Should we shorten that time down to 5 seconds then? Then it wont say enough about cars that drasticaly drop after 5 seconds.

How do we know there is no 550kW for even tenth of a second? Just because it is not displayed on the dash or in REST log?
What if it does not have enough resolution?

I tell you Model S can output 1MW of power. But for such a short time, one does not notice it.

Yup, and that will come into play later as the EV industry is forced to quote 30 minute continuous power, but that is not relevant here. The P85D doesn't produce 691 hp for *any* amount of time. Heck, I'd be happy if it only did so for 10 seconds at a time requiring a cool off of minute in-between. I'm not that demanding. I'm not going to the track. I don't need to drive at 100+ MPH for long periods of time.
 
Charge the car to 90%, strap it to a dyno and measure the hp.
You didn't answer the question: how long must it stay on the dyno at full power?
If you say one second (assuming a dyno with enough resolution) the result will differ from a dyno that needs 5 seconds to assess the power.

Is it really that hard to understand?

- - - Updated - - -

The P85D doesn't produce 691 hp for *any* amount of time.
"Any" being any time longer than what?
Don't say you looked at it at microsecond resolution?
 
To see how complicated this issue is read the report linked to below. Note the rated peak power of the motors of both the LS600h and the Hybrid Camry is disputed by our own government. Compare the motor power rating vs the dc-dc converter power rating vs the inverter power rating vs the battery power rating. Note all these "ratings" are still arbitrary.

In an "ideal" world Telsa would only advertise the peak hp delivered to the ground, but again that would be completely stupid because people would use that number when comparing cars.

There is a simple way to compare the Tesla P90DL vs the Porsche Mission E. Put them on drag race strip. Keep running them until the battery is drained in back to back races. Put them on difference race tracks. Put them on a high speed oval. Put them on a short track. Compare 1 lap performance vs 10 laps or whatever.

Magazines are not going have the capability to scientifically benchmark electric cars in every operating condition.


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Continuous duration varies significantly with motor speed and specified stator temperature limit for eachpower level. For example, the 2010 Prius PMSM is able to sustain a power level of 25 kW at 5,000 rpmwith 50ºC coolant for about 25 minutes with a stator temperature limit of 150ºC. However, the durationfor the same conditions held at 3,000 rpm is only about 6 minutes. There is no standard for establishingcontinuous or peak power rating specifications for motors designed for HEV applications such as the LS600h, Camry, and Prius motors. The significant impact of these conditions highlights a very importantreason for performing benchmarking tests on HEV subsystems – current technologies must be verifiedand thoroughly examined objectively before the results are used by the FCVT program and researchers.The influence of HEV specifications on technical goals and program planning would be drasticallydifferent if unclear published specifications of HEV systems were used as a baseline.

http://info.ornl.gov/sites/publications/files/Pub26762.pdf
 
Lied implies intent. The two motors added together under ideal test conditions do make 691 motor hp. Tesla never said 691 hp at stay or wheels. Yes, it was vague and misleading anyway.

You mean in ideal conditions where the power supplied is from some source other than the battery that is supplied with the vehicle. Really??? Or did I just misread your statement?
 
You didn't answer the question: how long must it stay on the dyno at full power?
If you say one second (assuming a dyno with enough resolution) the result will differ from a dyno that needs 5 seconds to assess the power.

Is it really that hard to understand?

- - - Updated - - -


"Any" being any time longer than what?
Don't say you looked at it at microsecond resolution?

I don't think you understand how cars work............

+1...
 
You mean in ideal conditions where the power supplied is from some source other than the battery that is supplied with the vehicle. Really??? Or did I just misread your statement?
Yah, I have trouble with this explanation too.

If I (somehow) plugged in my P85D's two motors directly to a bank of a dozen supercharger stalls and was able to run them for 10 seconds before they ate themselves, would the HP measured during that period be considered the "true" HP of the car? No. I don't think any sane person could believe "Yes".