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I ordered a Performance 3. The car at delivery was an AWD.
- Thread starter yul sam
- Start date
This is called "assuming facts not in evidence"
This is why I suggested that the person who was at the SC trying to get this issue resolved see if they could get some hard evidence one way or another. It's possible that there are hw differences, but I haven't seen anything posted that would prove it one way or another.
From a business model perspective, it would give Tesla lots of flexibility and future high-profit revenue streams if they could convert any AWD car to P3D- with an OTA update (this of course would depend on the definitive answer if there is a hw difference or not).
Daniel in SD
(supervised)
It's too bad some of us AWD owners didn't accidentally get performance enabled. Of course if I did I wouldn't be posting it on the forum. haha.
I still believe that all AWDs are Performance capable. Mainly because I believe that the rear motors in the Performance are identical to the LR. The Performance is only 50% more powerful than the LR and they've added another 200+lb motor to the front. How could such a large motor not produce 50% of the power of the rear motor?
I suppose it's possible they're using weak rear motors for the AWD. They could have stockpiled a bunch of them during first production. I'm just skeptical that the tolerance are loose enough to have significant power differences between motors and inverters.
I still believe that all AWDs are Performance capable. Mainly because I believe that the rear motors in the Performance are identical to the LR. The Performance is only 50% more powerful than the LR and they've added another 200+lb motor to the front. How could such a large motor not produce 50% of the power of the rear motor?
I suppose it's possible they're using weak rear motors for the AWD. They could have stockpiled a bunch of them during first production. I'm just skeptical that the tolerance are loose enough to have significant power differences between motors and inverters.
Perry
Active Member
"performance chassis” on the inside of the door is P+ only. My P- also have “no performance chassis” on the doors.
This is called "assuming facts not in evidence"
If you want to say that Elon's tweet was untruthful regarding drive unit binning and double burn in, that is your choice. However, it then makes it difficult to discuss anything since he is/was the major source of data.
I really think the issue is thermal versus short term motor net power handling. A 10% variance in on resistance is miniscule compared to pack voltage, but generates 10% more heat at the most temperature critical point.
Just look at the variation on this ST part. 18 to 25 mOhm at 25 C, typical is 30mOhm at 200C.
That's a 50% variance in resistance so a 50% increase in dissipation which increases the die temp which increases the resistance and so on...
Daniel in SD
(supervised)
Those are maximum specs. If you actually measure those devices you will probably find that they have much tighter tolerances. Manufacturers want their customers to design with plenty of margin so that a 6 sigma part that costs $.10 doesn't cause the failure of a $1k drive inverter.
50A * 25mOhm = 1.25W of power loss. That's a small fraction of ~400kW of power.
Right, it is likely conservative, but you don't know untill you test it, hence the burn in.
You calculated the voltage drop, like I said the net power to the motor isn't the important factor. Power dissipation is I^2*R so 50A @ 25 mOhm is 2500×.025 or 62.5 Watts. Compare to 18 mOhm at 45 Watts. Basically, for the same power dissipation, the current or torque or power drops by the square root of the deviation. So a 50% increase in resistance requires a 22% decrease in power. Conversely, if you know you have low resistance parts, you can get more power out of the drive unit.
Knightshade
Well-Known Member
Good thing I never said that, huh?
I said there's no evidence there's any actual HW difference.
YOU on the other hand claimed there was, with 0 evidence to support the claim.
I already explained what the binning is in my opinion-
They take complete drive units (whcih is what Elon ACTUALLY described as binned)- which are the exact same parts as each other- because otherwise "binning" them makes no sense.
They they test them (whole drive units, because again that's what Elon said)- and the highest scoring ones go into known-Ps from the factory... because that likely gives them a marginal reduction in future warranty costs.
But likely all of them are good enough to go into a P... because as Daniel notes, tolerances are really quite tight in all but the most tiny nanometer type electronics these days.
The fact we have at least 4 different reports of AWD-from-factory cars being flashed to P after/during delivery seems to support this case too.
If I have a bin of 1k 10% resistors and build two boards using them I can have one board with 9k of resistance and one with 11k of resistance. Those two boards have definate measurable performance differences. That is what I mean by hardware differences. One is over a threshold, one is below.
Regarding drive units, one is tested and proven to be P capable and one is (potentially) not (in the case of a motor that passed as AWD/RWD but failed as a P).
As to the exact tolerances, I do know know the spread, but I'd be interested to see a power SiC part with a sub 20% range for the important parameters.
Daniel in SD
(supervised)
Haha. My bad. And I'm an EE. This is embarrassing.
You're right that small changes in the efficiency of the drive unit will result in large changes in heat dissipation even though the differences in power output would be small.
So what's your theory on the cars that were delivered as AWDs and converted to Ps? Did they give those people the right cars but forget to enable the Performance?
It's funny that we're all arguing about this since it seems like there really is no way of knowing.
I know about Elon's tweet but that was a long time ago. Maybe they figured out that binning the drive units was a waste of time.
diamond.g
Active Member
Daniel in SD
(supervised)
The thing is they're not using a single SiC transistor on a board. They're using a bunch and unless they're sorting them before building he board all the variation will average out and the final product will have less variation. The chances of putting two parts on a board that are both at the max spec for a parameter are infinitesimally small.
Same VIN due to same drive units. Motors are equal, some are just more equal than others.
Ok I am now happy again. Whether or not the hardware is different I’m not sure. But if there a difference I have the performance setup. Thanks to an amazing and relentless service tech here in Vegas all has been resolved. They flipped a switch and I received the performance identifiers red lines , menu option and definite speed upgrade. Not a download of any kind but just opening up the options. To prove it I was given the attached paper. Notice the P75D and performance package noted. Also birthday is Sept 26View attachment 340225
Yes, on the macro it evens out, but on the individual part level the higher resistance part is not carrying its share of current (V/R), that causes the other parts to dissipate more and they hit the thermal limit.
I figure GF1 is producing more Ps than Fremont needed and they were put in AWD cars. Or the cars were intended to be Ps and were misconfigured...
It may very well be that it turned out after testing that all the parts are all good enough to be P. Or that only 10% get locked to non-P.
Shrugg...
That makes me feel better, perhaps they will do an over the air update and get me straight. I’m two states away from a service center.
Daniel in SD
(supervised)
Jedi2155
Model 3 has Arrived.
Maximum support ENGAGED. I finally realized what that round side button on powered car seats does....never played with it on my wife's car and haven't had powered seats until my Model 3.
That is a very interesting screenshot with the most interesting parts below
- Tesla refers to the P model as a P75D
- Pack Energy says 74 kWh?
- Birthday (exact build date?)
- Rear Glass Type: Would the models with the orange effect be different that than those with?
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