I actually think it is very central point when it comes to the point of this thread. Now we know that the fuse is THE part that is limiting the car from actually making the power Tesla initially claimed it would. And from what data we have available it seams like the current limit on the P85D is less than 1100 amps.
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[updated with *] P85D 691HP should have an asterisk * next to it.. "Up to 691HP"
- Thread starter krisg81
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- Driving Dynamics Model S
I actually think it is very central point when it comes to the point of this thread. Now we know that the fuse is THE part that is limiting the car from actually making the power Tesla initially claimed it would. And from what data we have available it seams like the current limit on the P85D is less than 1100 amps.
ERP
Ludicrous Member
Kind of missed my point. Power is the central point of the thread, and we are missing some critical information to complete the calculation, which is leading to a lot of assumptions. My point was that we can not take the 1300 or 1500 amps as the breaking point of the fuses. I agree something still seems wrong. 400 volts and 1300 amps does not make sense with the max draw seen of 416 kw. So is voltage sag that significant, or is the current being limited below 1300 amps for some reason other than fuse factor of safety?
stopcrazypp
Well-Known Member
It's more complicated than that. The first thing they did was advertise motor power (again, this applied to all models, not just the P85D). This is a number that models can't achieve at the shaft or wheels because of battery limitations, except for single motor 85kWh versions (S85 and P85). All it does is point out what the motor/inverter is capable of.
The next thing they did was add the two peak numbers for motor power for all the dual motor versions. This is fine for the ones with the same motors front and back, but the P85D has different motors/gearing front and back which makes it so the peak numbers might not match at the same rpm (so adding the two might be invalid, even putting aside the whole battery limitation).
They removed both numbers after there was much complaint over here at TMC about the 691hp number being misleading (I think it was mentioned somewhere in this same thread). Recently they added back motor power, although they never went back to putting a combined motor power for the dual motor versions. The only thing they didn't do so far is quote an actual power number for the P85D/P90D (they have done so for the other models). Offering the Ludicrous mode cheaper for P85D is a slight mea culpa. However, I think it is wishful thinking that they will offer it for free. After all, the S60, 60D/70D, 85D owners never got anything, even though they got quoted higher motor power numbers also, which their cars also can't achieve because of battery limitations.
Personally, I don't think they were trying to be maliciously misleading with the motor power. I think they are thinking of after-factory pack upgrades (which is beginning to happen with the 90kWh version), which is why it makes sense to quote a motor power (so you know what your car would be capable of at the max, in case a pack upgrade is offered). That's probably why they added it back. Perhaps they should have had both numbers from the start, but hindsight is 20/20.
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Yes, that's with a 1 foot rollout which is how manufacturers typically publish times.
There's a more complete discussion of this here:
Playing around with VBOX Sport.... 0-60 times...
Where I include times with and without the 1 ft rollout. My times did not decrease after 188. Also, I've rarely seen a manufacturer that can meet their 0-60 claims without a profressional race car driver trying multiple times under ideal conditions. Even launch controls on most cars doesn't usually meet the spec.
With the P85D, grandma can do it every time.
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What matters is they can't meet a 10.9 second spec from 11.7 actual with only an 86 hp increase.
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Agree and agree.
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Don't agree here. That would be the case for torque, but X kW piped into a motor will produce y hp at the motorshaft on an engine dyno at any RPM.....almost. I say almost because there are some small efficiency losses as RPM increases but they are tiny at the PRM ranges (18K RPM range) we're talking about.
There are more losses with the non linear friction of oil viscosity as the RPMs increase in the reduction gear and open diff, but even those are fairly small up to speeds 90 MPH. But we're not penalizing the MS for drivetrain losses after the motor. ICE cars have their lowest drivetrain loss in the 1:1 gear and they lose more at any other gear so when you get to higher speeds (on a dyno without air friction), shifting to a higher gear will result in an obvious hp reduction at the same peak hp RPM.
My calculated RWHP acceleration runs using my VBOX track within 2% of the REST API up to 80 MPH and then after that they start to diverge quite a bit more, but at that speed, air resistance starts to become the bigger factor here.
Car and Driver has conventionally used a 1-foot roll-out, for all its 0-60 times. That they do not affirm this standard in reporting their "3.3" result, makes me more cynical of them than Tesla. Too many others have.
I'm surprised there isn't already a 2.8 / 10.9 car someplace?
stopcrazypp
Well-Known Member
I'm not talking about efficiency losses between the two motors, but rather matching the peak power point. For example if the rear motor makes peak power at 50mph and front motor at 60mph (just making up the numbers) then together they will never make the sum of the two peak power numbers. At 50mph the rear motor may make the peak 470hp, but then the front won't make the 221hp. At 60mph the front makes 221hp, but the rear won't make 470hp. Thus if you measure the power from both at the same time, it will never be 691hp total at any point, even though independently there is a point that they make their rated output.
Yea, that's my point. It's an electric motor. They make peak power at all RPMs...or rather whatever kW your pumping into them.
stopcrazypp
Well-Known Member
Not according to the dyno graphs posted so far. They still have to ramp up to a peak power point and then ramps down afterwards. This is because power is a factor of torque and rpm. Torque is directly related to current and motors can't handle infinite current. Thus at lower rpms, there is still a limit to how much power you can output (even though you can output peak torque at an instant). As you reach higher rpm, the torque drops (because of back emf) which also limits power. That is why the peak power point is the somewhere in the middle.
The ideal power graph for the Roadster really illustrates this.
The only reason why there is some "plateauing" in some of the graphs is because the bottleneck is elsewhere besides the motor (likely the battery so far).
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Not according to the dyno graphs posted so far. They still have to ramp up to a peak power point and then ramps down afterwards. This is because power is a factor of torque and rpm. Torque is directly related to current and motors can't handle infinite current. Thus at lower rpms, there is still a limit to how much power you can output (even though you can output peak torque at an instant). As you reach higher rpm, the torque drops (because of back emf) which also limits power. That is why the peak power point is the somewhere in the middle.
The ideal power graph for the Roadster really illustrates this.
The only reason why there is some "plateauing" in some of the graphs is because the bottleneck is elsewhere besides the motor (likely the battery so far).
....and the REST API KW numbers exactly match the power output so the power fed into the motor matches what is measured at the wheels minus about 10%. The P85D hits peak power at 36 MPH at 90%.
The motors could handle 415 KW at 0 RPMs, but then you'd just spin all 4 tires. Elon even said 0-30 MPH is currently traction limited.
BTW, that dyno graph looks like one produced from using REST API KW and RPMs to calculate the torque and looks more like an S85 rather than P85D.
S85:
Heres one for my P85D:
The power at the wheels matches exactly the cars API kw * 1.34 (hp / kw) * (0.91 power train loss).
ERP
Ludicrous Member
You are probably correct on this point. They are different motors and do not need to make max torque at the same rpm. If the data showed the P85D drawing ~670 hp max, this would be a good explanation for missing the 691 mark. But the data indicates significantly less than this, which would mean the motor output would have to be incredibly peaky or significantly far apart to make this the main reason of missing the 691 combined hp.
So if the difference in peak output between the motors was only a few 100 rpm, or even 500-1000, there would be a huge power fall off on either side to account for the total combine power being much less than the 691 figure. I don't believe this is the case because power would have to fall so quickly that top speed would be severely restricted. Or the power output would have to be very non-linear.
The other possibility is that one motor makes a peak at 1,000 rpm and the other at 10,000 rpm (made up numbers). The power curve could be smooth and would combine to be significantly under the 691 figure. I suppose this is possible, but why would one motor be designed to make max power so late in the usable rpm range. Also, measured power curves do not appear to support this.
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stopcrazypp
Well-Known Member
If the Ludicrous update is actually going to deliver the HP that was promised many months ago, shouldn't that update be given free to P85D owners? I would think, if you bought your car based on Tesla representing 691 HP, that being asked to pay another $5,000 to get what you felt was already included in the original bargain would be upsetting. I'm not trying to stir the pot, I'm just making an observation that people don't seem to be as nearly upset as they were earlier. Nobody seems to be demanding a free retrofit based on the claim of false advertising, which some have accused Tesla of in this thread. So was that really the concern to begin with?
Speak for yourselfIn my conversations with Tesla this has definitely come up.
A-HA! I think you're heading down the right road with this, in my opinion.
Andyw2100
Well-Known Member
I've actually suggested that a few times. I think not only is it the right thing to do, but the good press Tesla could get by doing it would be worth a lot. Insane mode made quite the splash. People who know next to nothing about cars and next to nothing about Tesla have heard about Insane Mode. The value in "Tesla just replaced Insane Mode with Ludicrous Mode, and did it for free." would be huge!
Somebody at Tesla needs to realize this would be a lot smarter to do now then later when it's forced as part of a settlement in a class action. If they do it now, it will look like good will. If the do it after a class action suit is filed, it will just look like they're being forced to do it.
Unfortunately, based on the little bits of info I've gathered on this, I'm doubting Tesla will actually do the upgrades for free.
Changing their tune on that now, while it would likely mean that such a lawsuit could be avoided just because customers concerned about it would likely be appeased, probably won't happen for a few reasons:
a) They're still selling the Ludicrous mode changes as a $10,000 add-on for new P85Ds, meaning that if you don't choose that option you're still getting the power output that exists currently... which is totally unspecified so can be whatever they want really. So one way people would see this would be that they're giving existing owners a $10,000 upgrade for free.
b) More importantly, offering it for free to existing owners, especially if it is to fix their initial claims of 691 HP, would essentially be admitting their initial false advertising and thus likely making such a lawsuit easier for them to lose. While currently there are many owners who aren't even aware of this issue due to the impressive 0-40-ish straight line speed, many more would become aware of the initial issue if this were the case and thus many more chances for them to be sued. Keep in mind that the majority seem to be dismissive of this issue for whatever reason.
c) I'm not convinced the P90DL (or whatever we're calling it) or a Ludicrous-updated P85D is going to be capable of reaching the originally advertised 691 HP number on a dyno anyway, making such a giveaway to fix the original false advertising not really a fix anyway.
No matter how you slice it, providing the 691 HP number was false advertising. This isn't something the media pulled out of their butts, folks, like a lot of other numbers thrown around about Tesla. This was on the Tesla order page when I bought my P85D. While they may be able to get a pass on a technicality currently by not actually showing the combined number anymore for current buyers they certainly do not for anyone who purchased while the order page showed 691 HP. Combining the output numbers implies that the car could output this much power. Period. Since multiple tests confirm that it comes no where close, I'm pretty sure the implications of this are pretty black and white.
A free or at least reasonably priced (maybe $1-2k) update to make the car get reasonably close to the advertised 691 HP would be fine by me and would certainly put legal action out of my mind and the minds of many others, but at the same time it would likes put the thought in other's minds who hadn't previously considered it and who are previously unaware of this issue.
Currently no service center or person I've spoken with at Tesla even has any info whatsoever on the P85D Ludicrous mode retrofit nor any information on when it will be available for purchase... which I find odd since the CEO made a public announcement on the cost and all and many I spoke with weren't even aware of those details.
Tesla's lack of communication strikes once again.
stopcrazypp
Well-Known Member
For those suggesting a lawsuit, I'll put it out there again:
1) There is no SAE standard for EV power ratings (it is still under development) and Tesla never claimed that number was an SAE number.
2) Tesla claimed that number was "motor power" (which per their meaning is referring to what the motors can output on a motor dyno, given that they show both numbers now). Outside of the caveat about gearing that I mentioned, where the actual combined motor peak number may be lower than 691hp because of gearing differences, I find it unlikely that the motors can't handle the output claimed.
3) Tesla appears to be following electric motor industry standards in rating their motor(s).
I'm not a lawyer, but I presume that "motor power" terminology there was added with input from lawyers and that Tesla's lawyers are probably well aware there is no standard yet for rating EV power. And that allows them to say they have not made a factually false statement. It then becomes a case of how misleading that statement is. Any plantiff trying to sue Tesla on false advertising would have to demonstrate that a significant portion of customers was misled in regards to this (not simply themselves or the judge/jury).
I do agree with wk057 that there is no advantage to Tesla for offering a free upgrade, given that is essentially admitting fault. Keep in mind even if they do so, they can still be sued for false advertising (esp. if as people speculate that the Ludicrous upgrade doesn't give 691hp either on a dyno).
1) There is no SAE standard for EV power ratings (it is still under development) and Tesla never claimed that number was an SAE number.
2) Tesla claimed that number was "motor power" (which per their meaning is referring to what the motors can output on a motor dyno, given that they show both numbers now). Outside of the caveat about gearing that I mentioned, where the actual combined motor peak number may be lower than 691hp because of gearing differences, I find it unlikely that the motors can't handle the output claimed.
3) Tesla appears to be following electric motor industry standards in rating their motor(s).
I'm not a lawyer, but I presume that "motor power" terminology there was added with input from lawyers and that Tesla's lawyers are probably well aware there is no standard yet for rating EV power. And that allows them to say they have not made a factually false statement. It then becomes a case of how misleading that statement is. Any plantiff trying to sue Tesla on false advertising would have to demonstrate that a significant portion of customers was misled in regards to this (not simply themselves or the judge/jury).
I do agree with wk057 that there is no advantage to Tesla for offering a free upgrade, given that is essentially admitting fault. Keep in mind even if they do so, they can still be sued for false advertising (esp. if as people speculate that the Ludicrous upgrade doesn't give 691hp either on a dyno).
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