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