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I completely agree. The Tesla's make their pace 0-30.
I went out in the Lotus Exige V6 today. 0-60 time is 3.8-4.2 depending on who tested it, so the same as a P85. From personal experience I know it would destroy a P85 after 40 even in a drag race (forget corners). The instant torque of the Tesla would get the jump on it at the lights though, to get close you would have to press the launch mode button and look like an idiot sat revving waiting for the lights to change in city traffic
Can't wait until the P85D is available to try over this side of the Atlantic.
I believe that the EPA Wh/mile numbers are the "derived" from actual test data with some kind of multipliers and therefore did not want to use them.
The EPA range miles, however, are obtained based on test data, so I calculated Wh/mile using EPA range numbers and usable capacity of the battery (capacity - "bricking" reserve), as was shown in my original post.
The chart below, perhaps, will better illustrate what I was trying to explain.
The chart shows four points corresponding to the various Wh/mile that I calculated in my original post:
60 --> 274 Wh/mile
85 --> 305 Wh/mile
85D --> 299 Wh/mile
70D --> 277 Wh/mile
Step 1. Consider the progress from point 274 (60) to 305 (85): as battery cells added to the pack the battery capacity goes up from 60 kWh to 85 kWh, and energy consumption increases from 274 Wh/mile to 305Wh/mile due to increasing weight of the pack.
Step 2. Consider the progress from point 305 (85) to 299 (85D): as dual motor drive is added the energy consumption goes down from 305 Wh/mile to 299 Wh/mile due to optimized blending of two motors.
Step 3. The resultant line in blue (Step 1 + Step 2) represent combined effect of the increased weight due to added cells and dual motor drive on the energy consumption. What I was trying to explain in my original post is that energy consumption for 70D, if additional 10kW capacity would be added by adding cells to the battery pack similar to 85 variants, would be located on or very close to the blue line. As chart, however, shows 70D energy consumption is significantly lower than the corresponding point on the blue line. It is actually very close to the energy consumption for S60. This implies that the additional 10kW of battery capacity did not add appreciable weight to the pack. This giving credence to my theory that additional 10kW capacity was not obtained by adding cells to the pack, but keeping the same quantity of cells, but using 16.7% higher energy density cells, the same quantity of them as in the original 60 kWh pack.
brucet999
Active Member
I think your chart might be connecting the wrong dots. You have drawn a line from smallest pack and less efficient single motor, to largest pack and more efficient dual motors. If you connected the two RWD points and the two AWD points, I think you would have nearly parallel lines whose values track well with pack weight.
BTW, when attributing Wh/mi differences strictly to pack weight because presumably two small motors weigh about the same as one large one, you also have to consider the extra weight for AWD of a second reduction gear, front drive axles and articulated linkages to enable powered front wheels to steer.
Or am I missing something?
I think you are. Please read again description in Steps 1,2 and 3. In Step 1 I go from 60 (RWD) to 85 (RWD). In Step 2 - from 85 (RWD) to 85 (D). The line shown in my chart is just representaion of Step 1 and Step 2 combined. It therefore accounts for **both** increase in energy consumption as battery cells are added to the pack (from 60kWh to 85kWh) and decrease in energy consumption due to dual motor drive. This line is designed to model effect of increasing battery capacity by adding cells (as opposed to the case of adding battery capacity by using cells of the same weight, but with higher volumetric energy density).
The chart shows that 10kWh of capacity added to the 60 in order to get pack for 70D was not achieved by adding cells because if it would the 277 (70D) point would be located on the blue line.
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No. You have me draw a line between two points where two variables change (size of battery and single versus dual motor). You can't linearly interpolate for the second variable which is what you suggest we do. Besides, the Wh/mile curve should be parabolic. Add some generic weight savings anywhere but the battery because the EPA for the 70D model is measured on the latest release versus an earlier release for the 60 and there you have it. The point is exactly where we should expect it.
chickensevil
Active Member
But the problem with your numbers are all based on the assumption that the "reserved" pack amount is always .95% of the battery. First, why would it be a percentage in reserve? The car systems, electronics, and battery management would all draw the same amount of power as a vampire drain over time regardless of how big the battery is (within reason). No one has definitively answered that question. If anything, the closest thing to deriving that number points toward 300wh/mi being the EPA rating on the 85 (I can't speak for the others as I don't drive the others). When you look in the car on the energy gauge as soon as you go to 302/303 the dotted line appears slightly above the rated line and as soon as you go 298/297 it appears slightly below. Since you can't zoom in to be more granular on the car's energy gauge, the best I can do is take the middle number which is 300. But it certainly shows a dotted line *above* the rated line when you average 305 or more on your gauge.
This points toward 79.5kWh as usable. Or rather, 79.5kWh when the gauge will read 0 miles remaining (there is a slight buffer there, but again, noone has really gotten a definitive answer to how much range you have before the car shuts down and you have to be towed.
The real question is, did they choose to *always* keep 5.5kWh in "reserve", or even using your 4.25kWh in "reserve" or is it a percentage as you imply? Changing to a fixed number like that would certainly throw off all your calculations. I haven't done the math to see by how much, but I think it would be worth validating based on the car's output what it is saying the rated usage should be. This was why I took from the EPA's website since that at least was some kind of definitive source.
It may not seem like much, but 300 vs 305 is a little more than 1 kWh difference in the whole pack, which is more than enough to throw off all the numbers in your calculation. Your thought process is sound, but I think your assumptions are skewing the results.
This points toward 79.5kWh as usable. Or rather, 79.5kWh when the gauge will read 0 miles remaining (there is a slight buffer there, but again, noone has really gotten a definitive answer to how much range you have before the car shuts down and you have to be towed.
The real question is, did they choose to *always* keep 5.5kWh in "reserve", or even using your 4.25kWh in "reserve" or is it a percentage as you imply? Changing to a fixed number like that would certainly throw off all your calculations. I haven't done the math to see by how much, but I think it would be worth validating based on the car's output what it is saying the rated usage should be. This was why I took from the EPA's website since that at least was some kind of definitive source.
It may not seem like much, but 300 vs 305 is a little more than 1 kWh difference in the whole pack, which is more than enough to throw off all the numbers in your calculation. Your thought process is sound, but I think your assumptions are skewing the results.
Because reserve is not there for other consumers to keep on working while the car is stranded but for the voltage not to drop too low too quick.
Reserve can change when tesla decides they can afford to allow voltage to drop lower or when they change their minds and raise the "EndOfFun" bar.
These maximum and minimum battery voltages have already changed a few times.
dirkhh
Middle-aged Member
Of course we're all just theorizing about what is happening inside the battery pack, but it's fun. Lets see 85 kwh X 1.167 =99.2 kwh. Pretty close to that magic 100 kwh mark. Just sayin...
The problem with that is that the range changes rarely hold, and revert back to the pre-FW update estimates once the systems have a chance to re-calibrate. If the absolute voltage ranges had changed, that wouldn't happen.
dirkhh
Middle-aged Member
There are a ton of factors that go into the estimated range. I would not consider those "evidence" that the boundary voltages (on either end) have been changed.
I noticed on the specs tab that the S70D is listed as having both 85 kWh and 70 kWh battery packs.
I'm guessing that's incorrect.
Or could it mean 85 kWh, software limited to 70 kWh?
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Doesn't work like this. The Model S is traction limited at low speeds, so power increases linearly until peak output where it stays mostly linear until it drops at higher speeds.
(theoretical+dyno graphs from TMC user WarpedOne)
Interesting. I was wondering if Tesla might replace the old 85 kWh packs from all of the returned S85, P85, P+85 when people upgraded to the 85D. If those old packs had "degraded" by 10-15%, they would be in the 70D range. Tesla could put new batteries in the 85 kWh CPO's, put the old packs into the 70D's and nobody would know that they had degraded. It's probably not legal to put "used" parts into a new vehicle, so just speculation and definitely not an accusation.
Olle
Active Member
That's why I wrote AVERAGE 257kW DURING its travel toward 60 mph. Yes peak power is higher at some point.
Gtoffo
Member
I think I agree with you, but the correct graph would still leave the 70D out of the line. The weight increase from the addition of a dual motor should be more significant for the 60kWh battery (lower overall weight) so the real graph should have the second orange line sloping less and starting from a higher point than the one I've drawn. Still we can consider this a conservative estimate which should confirm that the new point is OUTSIDE of the efficiency made possible by just increasing cells. Agree?
@vgrinshpun do you agree that the two effects should not be combined in that way? Or am I missing something? The increased efficiency effect of a dual motor should shift the data point for the 60kWh battery down.
Rampant speculation is that the modules are now the same as the modules in the 85kWhr pack. This would mean a higher voltage than 60kWhr modules and additional efficiency gain from lower losses. I think this is the best explanation I have seen for them being the same cells.
That being said, I believe tesla and panasonic have to be testing gigafactory cells now. They may even be at the module and pack level testing.
That being said, I believe tesla and panasonic have to be testing gigafactory cells now. They may even be at the module and pack level testing.
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