Calling P85D owners world-wide for survey and complaint letter

[Andyw2100]

This qualification is my point. Your expectations are arrived at through a bias. Why hasn't Tesla responded the way you want...policy? That's conjecture on my part, but I see no reason that it isn't just as likely. It, of course, could also be exactly as you believe. However, without information neither possibility is more likely than the other...as galling as that may be.

Well, on your last point we'll just have to agree to disagree. I don't view the possibility that Tesla simply has a policy not to respond to questions about horsepower specifications as just as likely as what I believe because there is no historical basis for that. Tesla has responded to questions about horsepower before, on other models. They've responded to ALL questions before. So if it's just "policy" not to respond to these questions, there must be a reason for that policy.

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Thanks. I don't intend to jump in with both feet and reach any conclusions, I'm watching from the sidelines - but I want to feel comfortable that data is being collected properly; I *definitely* don't trust anything displayed on the instrument panel related to power (other than relative things), and don't know how much I can trust the streaming API data without knowing how it's determined and whether it can be reflective of reality.

I'm sure sorka will jump in. He's a smart guy, and I think he has done his homework with respect to the validity of the API data. And of course even if numbers obtained from the API could be inaccurate by, say 5% or even 10% (and I have no reason to believe that's the case) we still wouldn't be close to reconciling the max HP at the battery with the 691 HP claim.

 

[sorka]

How was that measured? Did someone attach a current loop to the HV cable to measure it with high-frequency/granularity calibrated equipment, or were you relying upon the streaming API data or, worse yet, the dashboard gauge? I've seen a lot of people draw conclusions from poor data sources (like the "my power is perfect and I get no voltage surges because the dashboard always shows 235V" argument)... and would like to hear how maximum power draw was determined?

I don't have a dog in the fight about the P85D, I'm happy with my P85 and will be happy with the performance X. But I do have a dog in the fight for proper data collection mechanisms and the use of bad data.

Integrating the "power" field samples (4 samples per second) together from the streaming API over a nice long run of 30 minutes adds up to precisely the amount that is ticked off in the trip energy accumulator. That test was performed with the AC off. The trip energy accumulator tracks pretty well with wh / mile usage and total battery usage. If it didn't, then the 76 kWh of battery we have wouldn't add up either.

The API reading is just another tool to correlate the dyno runs that have already been done on chassis dynos and power calculated from vbox runs as well as acceleration metrics. Nobody is pointing at just the API and saying that's proof. It's just one tool being combined with a bunch of other tools.

 

[JER]

You clearly don't understand my argument.

You clearly don't get my argument that not knowing how the number was arrived at is irrelevant, because we do know what the most generous system possible for an actual measurement is, and the car doesn't come close to it.

How was that measured?

There are two sources for peak power, obtained through three channels:

Source one is the car's internal instruments. Can be estimated from the dashboard instruments, or read in numeric form using the REST API.

Source two is the current limits disclosed by Elon Musk. This, along with known data about the battery's performance, place a theoretical maximum on the pack's output power. This is closely in agreement with source one.

Clarification: Actual current is, as expected, less than the theoretical maximum.

 

[FlasherZ]

Integrating the "power" field samples (4 samples per second) together from the streaming API over a nice long run of 30 minutes adds up to precisely the amount that is ticked off in the trip energy accumulator. That test was performed with the AC off. The trip energy accumulator tracks pretty well with wh / mile usage and total battery usage. If it didn't, then the 76 kWh of battery we have wouldn't add up either.

The API reading is just another tool to correlate the dyno runs that have already been done on chassis dynos and power calculated from vbox runs as well as acceleration metrics. Nobody is pointing at just the API and saying that's proof. It's just one tool being combined with a bunch of other tools.

Great - thanks.

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Source one is the car's internal instruments. Can be estimated from the dashboard instruments, or read in numeric form using the REST API.

This, by itself, can't be trusted. But I'm satisfied with sorka's answer that it lines up over a long period.

 

[JohnSnowNW]

You clearly don't get my argument that not knowing how the number was arrived at is irrelevant, because we do know what the most generous system possible for an actual measurement is, and the car doesn't come close to it.

Again, just like someone using dyno to try and get 707 hp on the Hellcat. You are making assumptions, and if you disagree with that, fine.

 

[JER]

Again, just like someone using dyno to try and get 707 hp on the Hellcat. You are making assumptions, and if you disagree with that, fine.

No. Not at all like that.

Battery output doesn't even include PEM or motor losses. It's even more generous than shaft bhp. There is no measurement you could make of any system performing as it would do in the car that would be higher than this. It's the complete opposite of looking for bhp at the wheels.

 

[JohnSnowNW]

Battery output doesn't even include PEM or motor losses. It's even more generous than shaft bhp. There is no measurement you could make of any system performing as it would do in the car that would be higher than this. It's the complete opposite of looking for bhp at the wheels.

BHP is measured with the engine outside of the vehicle, under lab conditions. Is it even required to be hooked up to the same fuel pump that will be installed in the vehicle? Point being you are limiting the the numbers to how it would work in the vehicle, when the same consideration isn't made for bhp.

So, again, like the guy trying to meet the specifications of the Hellcat, while using the limitations of the vehicle...and no knowledge of how Dodge's hp numbers were calculated.

It's exactly the same thing.

 

[sorka]

BHP is measured with the engine outside of the vehicle, under lab conditions. Is it even required to be hooked up to the same fuel pump that will be installed in the vehicle? Point being you are limiting the the numbers to how it would work in the vehicle, when the same consideration isn't made for bhp.

So, again, like the guy trying to meet the specifications of the Hellcat, while using the limitations of the vehicle...and no knowledge of how Dodge's hp numbers were calculated.

It's exactly the same thing.

J1349 requires hooking up the same accessories, full intake, exhaust, pumps, alternator, starter, and emission controls the engine will be hooked up to in the production vehicle. The test is performed on an engine dyno and then corrected for atmospheric conditions to sea level. The is SAE net horsepower. Prior to 1972, manufacturers measured engines without accessories and used open exhausts without emissions equipment which resulted in much higher horsepower readings than when installed in the vehicle. This was GROSS horsepower and manufacturers aren't allowed to specify horsepower like this anymore.

I'm pretty sure most P85D owners would be happy with 515KW (691hp) at the battery prior to any conversion or drivetrain losses. It still means less than 691 hp by the time it makes it all the way downstream to the motor shafts, but it would be a lot closer to what paid for than what we got.

 

[JER]

BHP is measured with the engine outside of the vehicle, under lab conditions.

Ever done this?

I have. On a Superflow SF-901. For years.

Is it even required to be hooked up to the same fuel pump that will be installed in the vehicle?

No, but it is required to be run under conditions representative of those in the vehicle. Under SAE regulations, it must have all accessories fitted and drawing their usual power. The stock exhaust system for the vehicle must be fitted - all of it. Pokes out quite a way.

The rules are intended to prevent manufacturers from publishing shaft output figures that are wildly discrepant with what actually happens in the vehicle. Those rules are essentially a record of the many creative ways that manufacturers have tried to cheat their customers; a new trick is discovered, and it goes on for a few years until its forbidden.

The intent of engine output figures is to give you a representative idea of how a powerplant will perform in the vehicle.

Point being you are limiting the the numbers to how it would work in the vehicle, when the same consideration isn't made for bhp.

As far as regulators are concerned that is the only consideration.

So, again, like the guy trying to meet the specifications of the Hellcat, while using the limitations of the vehicle...and no knowledge of how Dodge's hp numbers were calculated.

It's exactly the same thing.

Nope. It's the exact opposite thing.

To deliver 691hp at the motor shafts, output of the battery would have to be significantly higher than that. It's ~150hp lower. I'm giving the P85D a more charitable assessment than it's entitled to.

I also note that every Model S variant prior to the P85D launch actually delivered the rated motor power. Also, even now the PxxD models are the only ones where actual power is not given in the specifications. Tesla aren't even following their own conventions, past or present, where their flagship is concerned.

A time will come where regulations for BEVs have been straightened out and these shenanigans are explicitly forbidden. I think it would be far more in keeping with Tesla's ideals if it were to behave itself ahead of that and without being forced to, though.

 

[JohnSnowNW]

J1349 requires hooking up the same accessories, full intake, exhaust, pumps, alternator, starter, and emission controls the engine will be hooked up to in the production vehicle. The test is performed on an engine dyno and then corrected for atmospheric conditions to sea level. The is SAE net horsepower. Prior to 1972, manufacturers measured engines without accessories and used open exhausts without emissions equipment which resulted in much higher horsepower readings than when installed in the vehicle. This was GROSS horsepower and manufacturers aren't allowed to specify horsepower like this anymore.

Thanks for the information. See, this is great, we know the specific standards of how the testing is done for bhp. It would be nice to know how the testing was done for the P85D.

 

[sorka]

Thanks for the information. See, this is great, we know the specific standards of how the testing is done for bhp. It would be nice to know how the testing was done for the P85D.

I think we'd all like to know that. But whatever they used wouldn't be able to turn 555 hp at the battery into more than 555 hp downstream at the motor shafts.

 

[JER]

I think we'd all like to know that. But whatever they used wouldn't be able to turn 555 hp at the battery into more than 555 hp downstream at the motor shafts.

Either that or someone's getting a Nobel Prize.:wink:

 

[Hookmaker]

An update:

Last week we finally managed to get through to the Tesla Motors Executive office and this is the email that we received from Elon (through his exec. assistant Sam Teller).

"Hi Ken,



I work in Elon Musk’s executive office at Tesla. Elon received your email and wrote the following reply, which he asked me to share with you.



There is a software update in V 7.0 (only for performance versions of the Model S) that allows the driver to command the battery to the optimal temperature and charge state for maximum power. Normally, the battery is optimizing for range and long life, so 0 to 100 kmh acceleration can be affected by 0.2 seconds or more if too cold, too hot or at the wrong charge state. Occasionally pressing max performance will not have a noticeable negative effect on battery life, but it should not stay there all the time. It is important to note that being at 100% state of charge does not deliver the best acceleration -- lowest impedance is at ~90% SoC.



I do want to emphasize that there has not been any reduction in insane mode performance for customers from the benchmark vehicle used by Motor Trend to establish the 0 to 60 mph (96.6 kph) in 3.1 sec. This was achieved at the 1300 Amp level, with no upgrade to the fuse, contactor or battery spine. However, they used a base vehicle and medium weight driver. Larger occupant weight and adding options that increase weight will reduce the acceleration. Also, the Motor Trend standard excludes the first 28 cm of rollout. Including this rollout adds approximately 0.2 seconds to the acceleration.



One final note is that, while gasoline cars get worse with altitude, electric cars actually get faster. All cars experience reduced air resistance, but gasoline cars become increasingly oxygen-deprived the higher they go. The Motor Trend test was done at approximately sea level, so the Model S will outperform a combustion car of the same nominal acceleration as altitude increases.




All the best,



Sam"



We will continue from here and state progress as we go along.

 

[jerjozwik]

well thats cool you got an explanation, kinda bummed to see "Max Battery Power" coming to all PxxD cars...

 

[Niclas]

He actually wrote "all performance model s", meaning the P85 as well?
nice to finally recieve a reply!
I am also surprised that 90% SOC yields better acceleration than 100%.

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In addition, the explanation of "base model" without any options yielding acceleration of 3.1s, also indirectly implying that P90DL also is timed 0-60 with rollout subtraction.

 

[AmpedRealtor]

Seems pretty straightforward to me, not sure what else people want.

 

[AWDtsla]

well thats cool you got an explanation, kinda bummed to see "Max Battery Power" coming to all PxxD cars...

What? Why? :cursing:

Tesla should leave all new features out. Ignorance is bliss.

 

[AmpedRealtor]

well thats cool you got an explanation, kinda bummed to see "Max Battery Power" coming to all PxxD cars...

Why would you be bummed about a feature being introduced across multiple models? That's a good thing.

 

[Pete90D]

I am also surprised that 90% SOC yields better acceleration than 100%.

Tesla Racing Channel commented on one of my videos and said that all his tests at the drag strip showed he got the best times at 85%. The best time I got was right around 85%.

 

[Andyw2100]

Seems pretty straightforward to me, not sure what else people want.

How about an answer about the horsepower issue, which was not addressed at all.