iKhalid
Member
Anyone knows when the weight became lighter? My model S left the factory in Feb 2014... Did I get the lighter version? (I doubt it)
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chickensevil
Active Member
Ok, so for those who hadn't heard or keeping tabs on this one, the weight has been modified slowly over time. As they have improved different parts, the weight has just naturally dropped. There is no definitive way to say what you have and don't have. The comment from the Earnings Call (feel free to go listen to it or read a transcript!) was that the car the released in 2012 and the car today are two different cars in terms of weight. They have shed "a couple hundred" pounds... but it wasn't noticeable changes from week to week, but rather small adjustments over time. Hope that helps
1) Could you mean 436 HP or even 336 kW? In another test last year they got 428 HP.
2) In an ICE vehicles specs, is the listed horsepower at the wheels?
No, generally vehicle specs (including the Tesla, AFAIK) are not done at the wheels, but rather at the output shaft of the motor/engine. In an ICE vehicle, the general rule of thumb is that there are between 15 and 20 percent driveline losses between the engine output (measured out of the car on an engine dynamometer) and the power you'll measure on a dyno at the wheels.
The parasitic loss for a Tesla is presumably a lot less, since there isn't a transmission, but it's also not zero since there is still a gearbox and U-joints between the motor and the wheels.
That said, wheel dynos are notoriously fraught with their own inaccuracies, so comparing pulls from one dyno to another is really not that instructive.
iKhalid
Member
Thanks for the clarification. Now I feel betterOk, so for those who hadn't heard or keeping tabs on this one, the weight has been modified slowly over time. As they have improved different parts, the weight has just naturally dropped. There is no definitive way to say what you have and don't have. The comment from the Earnings Call (feel free to go listen to it or read a transcript!) was that the car the released in 2012 and the car today are two different cars in terms of weight. They have shed "a couple hundred" pounds... but it wasn't noticeable changes from week to week, but rather small adjustments over time. Hope that helps
chickensevil
Active Member
Sorry yes, I was flipping back and forth between windows to get the right values and I think I just typed the wrong thing. I have corrected the post to say 436HP
I believe manufacturer specs are always listed as coming from the source, not the wheels. But all a normal person is able to test is power at the wheels. So this is why I was suggesting that while we likely are only going to see HP somewhere around 436-440, the real power being able to pull through the inverter is much higher. There is likely some loss as that power goes into the motor, and then some more loss as it comes out of the motor and spins the wheels (although not nearly as much as the motor loss). I believe the motor was something like 80-85% efficient at power conversion so taking the better of that (85%) would put the power off the inverter somewhere around, 512HP or 382kW, is that about what people are seeing on their Performance cars?
So I pulled some screen grabs from youtube videos and they all seem to cap at around the same point on the dial:
You are welcome to try to guess what that actual value is... it is a Log scale, so being slightly above 320 is quite significant.
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Using some rough guesses, The top of the gauge would be 640. Based on the two visible tick marks and the spacing of the line on the current read out, I can make a guess that it is pretty close to the equivalent of one tick mark up from the 320 point with there being 6 ticks to get to the top. The middle point would be 480 so one tick would be ~53.3 kW. So, based on that, if it is one tick up (or pretty dang close) that would be a whopping 373kW off the inverter (assuming that is where this readout is being pulled from). That puts me pretty close to what I was guessing up above using what I could recall about the inefficiency of the motor being 85%. If you max at 373kW you would be pulling 500HP.
Again, these are just guesses... without seeing Tesla's real numbers. But it would line up with what we know and see happening.
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Who was complaining? I thought people were thrilled that they were getting better than advertised? Just trying to figure out what the real value is
I don't know why any of this would be surprising. But just as fuel consumption is a very imprecise indicator of performance, so is power at the battery. If we accept that the power meter is accurate, then the dyno measures efficiency, but I would say that is a very interesting measurement
About >320 kW being more than rated - yes, and by no small amount either. But that is before all the losses, probably right at the battery. I think it's measured at the battery because it clearly shows power being used when the AC or the battery heater is running.
I assumed that Tesla listed the power at the motor shaft in the 362 hp figure, which would yield an efficiency of about 84 % - not bad at full power. When RS Tuning measures 405 hp, that would be more like 94 %, which is stunningly good. And as if that wasn't enough, that number includes the mechanical losses in the gearbox and differential! The percentages should be reduced a little, by the way, as the power meter is showing more than 320. The next number on the scale would have been 640. Maybe it's showing 350?
*edit* I agree with chickensevil's estimate. If it's taking 370 kW (496 hp) from the battery and the measurement of 405 hp at the wheels is correct, then the efficiency would be 82%, which may be a realistic figure.
My display looks exactly like the middle one in chickensevil's post above.
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See this thread:
Peak KW on S60, S85, and P85
brianman reported circa 367 kW on his P85. Don't have time to look it up now.
Previously, the highest an S85 saw was 320 kW, but now we have reports of an S85 exceeding 320 kW power draw.
Peak KW on S60, S85, and P85
brianman reported circa 367 kW on his P85. Don't have time to look it up now.
Previously, the highest an S85 saw was 320 kW, but now we have reports of an S85 exceeding 320 kW power draw.
If you look at the DragTimes video, you will see that his SoC is fairly low, around 40 %. Even so it almost reaches 320 kW. It actually limits power and does 0-60 in 4.9 anyway.
When I get the dashed "power limited" line I can feel that it's slower (ehrm - less quick) than usual, and I think I can feel it before the dashed line actually appears. I think it has to have a high state of charge and the battery must not be cold to go over 320.
When I get the dashed "power limited" line I can feel that it's slower (ehrm - less quick) than usual, and I think I can feel it before the dashed line actually appears. I think it has to have a high state of charge and the battery must not be cold to go over 320.
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Yes. I've only seen over 320 in my S85 once or twice. ~90% SOC, beginning of trip (a couple of 100 m from home) and ~25 deg C outside. I'd say it looks exactly like the screenshots above. But on an S85 and not P85.
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Ehm. No. If the scale is logarithmic, then the middle mark between 640 and 320 wouldn't be 480. It would be lower. Or do you assume that the scale is linear between each printed number?
Oops. I said I agreed, but you're right, of course.
I did some testing today. I charged from 80 % to 90 % on a supercharger while buying lunch, disconnected and parked away from the chargers as it was finished when I got back. Then I ate for about 20 minutes and left. Ambient temp about 20 deg C. Accelerating from 100 to 125 km/h it would repeatedly hit 320 and stay there, but the needle did not completely clear the 320 mark. It edged above the mid-point of the mark every time, though. Later, at about 75 % SoC, it stopped a pixel or two below 320.
I swear I've seen it pass the 320 mark by several pixels on earlier occasions, but I could not make it do it today.
I'm convinced SoC affects how much power you get.
Yes, I had the same idea. From somewhere around 120 km/h power started to drop again, it may be past the power peak at 110. If so, it may not have reached full power before well past the peak.
chickensevil
Active Member
You are right, hrmmm if only there way a way to sort out the scale... I am not aware enough about log math to get the right number... Hrmmmm.
Guys, just read the actual value from the API and there is no sorting out that needs to be done. Grab yourself a copy of VT or write your own.
chickensevil
Active Member
Hmmm I have that and never realized that was a value that was captured
Seems like you would have to go test it a couple times in order to hit it within the 4 second window.
scott jones
Member
It NEVER made sense to me mathematically that a 60, S85 and P85 would have the times Tesla lists.
It's my opinion their claimed GAP between S85 and P85 is not true.
There's a 60 "hp" difference between the S60 and S85, with a .5 second difference in 0-60 times. (5.9 v 5.4)
Yet between the S85 and P85 there's only a 56 "hp" difference (from memory) between the two.
And YET, there's a HUGE 1.2 second difference in 0-60 times! (5.4 v 4.2) BS!!!
My bet is, they wanted it to look like a huge difference when trying to sell the more expensive P85.
Here are my armchair guestimations. They should be far more evenly spaced.
S60 = 5.8 (or better. I think it's under-rated) I've driven a 5.8 second car, and this is faster.
S85 = 4.9 (The testers figures. And the S85 is a hell of a lot faster than the claimed 5.4. This would make it .9 seconds faster than S60.)
P85 = 4.2 (Tesla's rating. That makes sense given the slightly less "hp" increase and extra weight of the car which gives it a .7 increase)
Now doesn't this make more sense! Sorry if this repeats what anyone else said.
It's my opinion their claimed GAP between S85 and P85 is not true.
There's a 60 "hp" difference between the S60 and S85, with a .5 second difference in 0-60 times. (5.9 v 5.4)
Yet between the S85 and P85 there's only a 56 "hp" difference (from memory) between the two.
And YET, there's a HUGE 1.2 second difference in 0-60 times! (5.4 v 4.2) BS!!!
My bet is, they wanted it to look like a huge difference when trying to sell the more expensive P85.
Here are my armchair guestimations. They should be far more evenly spaced.
S60 = 5.8 (or better. I think it's under-rated) I've driven a 5.8 second car, and this is faster.
S85 = 4.9 (The testers figures. And the S85 is a hell of a lot faster than the claimed 5.4. This would make it .9 seconds faster than S60.)
P85 = 4.2 (Tesla's rating. That makes sense given the slightly less "hp" increase and extra weight of the car which gives it a .7 increase)
Now doesn't this make more sense! Sorry if this repeats what anyone else said.
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