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where does the extra acceleration come from in 85/P85 vs. 60?

This is just a technical question out of curiosity -

Where is the extra acceleration coming from in the 85 and P85? For the 85, is it that the additional batteries (I assume) are dynamically switched to run the motor in series, and therefore you get that much more voltage to the system? And then for the P85, is there actually a larger motor?

Thanks.

the P85 has a different inverter and if I have heard correctly, the 85 and 60 are about the same speed. Tesla likes to jack up the 0-60 times to keep insurance rates down

The P has a different inverter. It is hand wound which apparently allows for denser windings. The 85s can deliver more current than the 60s so are slight faster for 0-60 times per the Tesla website.

O

It's the motor in the P that is supposedly hand wound. The inverter is higher capacity so it can pass along more juice to the hand wound motor.

Cheers!

When you have fewer cells (the voltage is the same, so the difference is in the number of parallel cells), the power available at a given discharge rate is lower.

Ie, if you have 17 cells in parallel supplying 1A each, you get 17A at the cell voltage. If you have 12 cells in parallel, you only get 12A. Now you might be able to draw more current from the smaller pack, but you are then discharging at a higher rate which causes greater degradation and builds up more heat in the batteries.

@ goneskiian : During the factory tour I asked specifically if there was a difference between the 60 and the 85 motors, and if so what it was, and I was told it's the same motor. So that leaves the inverter as a source for the difference.

@diegoPasadena - I am pretty sure the inverter is the same as for S60 and S85, and is different only in the P85 and P+.

jat, yes, this was settled long ago. Inverter is upgraded on the P85. All Tesla sources confirm.

May not be handwound in volume production, the Roadster Sport had those, and perhaps the first Ps.

85 and P85 is well understood - definitely a different inverter, and allegedly a hand wound motor.

60 to 85 has not been confirmed (to my knowledge). If the 60 is indeed slower to 60mph and down on power, then that implies fewer kW. If the motor and inverter are the same, then the 60 must be lower on voltage, current or both. This could be fewer cells, or same # of cells but different chemistry.

I think the baterry voltage is likely always 360 VDC to correspond with the Superchargers.

The S60 and S85 may easily have the same inverter with a different inverter firmware onboard, effectively limiting the power of the S60.

@chrisdl - if the voltage is the same, which I believe to be the case, lower kWh storage capacity means lower peak current output.

jat: That makes sense.
You'd still need an adjusted inverter (firmware or otherwise), or you'd fry your battery.

I talked to the advisor in Fremont and he explained.

All three cars have the exact same motor. The S60/85 both have the same inverter, while the P's have a high powered inverter. The S60 is software limited in its acceleration, though the limitation is fairly minimal (only a fraction of a second), so telling the difference between a 60 and an 85 would be fairly hard to do, even driving them back to back. The high powered inverter on the P provides a larger pipe for electrons to flow, thus allowing faster acceleration. To be clear though, he was very clear that the S60 is neither firmware nor hardware limited, it's software, not hardware/firmware.

Hum... Firmware = Software :-)

yodasminion:
The difference between an S60 and S85 is a fraction of second for which acceleration? 0-60 mph, I guess? Official number is that an S80 is half a second faster than an S60. I agree that you'd be hard-pressed to feel that difference in practice.

When driving the car, the difference between 302 and 362 bhp should be noticeable though. We're talking about a 20% uplift in power, after all.

This is interesting stuff. I guess that about 40% of the buyers will choose a 60 kWh Model S, and about 40% of the buyers will choose a 85 kWh Model S, and about 20% of the buyers will choose a Performance or Performance + 85 kWh Model S. That's just a rough guess, by the way.

Don't think so, as far as i can tell most have the P version, then 60, then 85.

@Navi - in the ATL group, there are about 3 P85s, 1 P+, 1 S40, 2 S60, and over 25 S85s (a couple of those are signatures).

Tesla Motors have never mentioned about this. Elon Musk once mentioned that the demand for the 40 kWh Model S was only 4% of the total of all Model S demand.

Is that ATL group a good and reliable source? What exactly is ATL group?

Maybe Tesla will undisclose this information in 2014, when the full year of 2013 will have been ended.

the s60 and s85 both have power limit of 240kw, the p85 has power limit of 320kw.

don't know why the s85 is faster than the s60. think it may have to do with more cells allowing power to be pulled out quicker. but peak for both the same.

Guys, you're all wrong - THIS is the difference:

http://www.youtube.com/watch?v=3S4_1z50rqs

eddiiemoy:
Where do those numbers come from?
From the Tesla spec page:

Peak Power (Vehicle specific power when battery is taken into account):
60: 225 kW
80: 270 kW
80P: 310 kW

Long term, Elon originally thought the 60s would be the most popular. So far, 85s are in the lead.

lmao @shop

I have achieved 318kW peak in my S85 at the track, as reported by the streaming API and confirmed roughly from the power gauge (though it gets cramped at the top end since it is log-scale so it is hard to be accurate).

@Benz - ATL = Atlanta

Typo in my post: 80 = 85 and 80P = 85P ... Duh! :)

What have we learned so far:
(Side note: Some numbers are approximate (but all are based on actual specs!), however they still give quite an accurate idea of what you can do with each motor / battery combo.)

1) S60 and S85 have the same motor, but different batteries.
P85 has another, more powerful motor.

2) Motor specs (from Tesla website)
Power:
S60: 285 kW - S85: 285 kW - P85: 350 kW (WITHOUT taking battery into account = theoritic)
S60: 225 kW - S85: 270 kW - P85: 310 kW (power WITH battery taken into account = realistic)
Torque:
S60: 440 Nm - S85: 440 Nm - P85: 600 Nm

3) Number of cells per battery (each cell has a capacity of approx. 10 Wh, rounded for simplicity's sake)
=> 60 kWh battery has about 6000 cells.
=> 85 kWh battery has about 8500 cells.

4) Battery is charged at 360 VDC at supercharger
=> About 100 (one hundred) 3.6 V battery cells in series in a single bank.

5) Number of banks per battery
* 60 kWh battery has about 60 banks of 100 cells
* 85 kWh battery has about 85 banks of 100 cells

6) Maximum discharge current
Maximum discharge current is approx. 10 A per cell.
=> 10A per bank of 100 cells
=> 60 x 10A for 60 kWh battery = 600 A
=> 85 x 10A for 85 kWh battery = 850 A

7) Maximum discharge power, at 360 V per bank
* 60 kWh battery: 600 A x 360 V = 216 kW
* 85 kWh battery: 850 A x 360 V = 306 kW

Considering my rounding errors, this sounds like a pretty accurate calculation.


Conclusion:
* S60 is limited by maximum battery discharge level of 60 kWh battery
* S85 is limited by maximum power of motor
* P85 is limited by maximum battery discharge level of 85 kWh battery

There you go :-)

@chrisdl - I agree with your conclusion. One thing you don't consider is that resistive losses become quite large at high currents. Ie, at 320kW output you are losing about a quarter of the power to waste heat (which is also why it heats up quickly when driving at the track). A 60kWh car will have this problem worse, as the current per cell is higher at lower overall power levels as well.

http://www.teslamotors.com/en_GB/forum/forums/analyzing-car-efficiency-d...

jat:
Thank you, that's excellent info. I'll try to incorporate that as well.
It seems that Tesla draws a seriously high current out of the cells under full load. Probably more like 14 A instead of my initial estimate of 10 A. Wow! I need to recalculate :-)


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