**Drivetrain-battery combo performance differences S60, S85, and P85**

*On the official Tesla Motors forum there was a thread where someone asked where the difference in performance between de S60, S85, and P85 came from. Well, I did some digging and found some answers. I thought these answers where interesting enough to share with TMC. Feel free to kick my $ss if you don't think so :wink:*

Anyways, here's my post:

Anyways, here's my post:

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 drivetrain / battery combo.)

UPDATE 1 (green)

- more accurate cell count per battery

- increased maximum load current of a single cell to 12.5 A

- replaced 'motor' by 'drivetrain' to avoid motor/inverter discussions

UPDATE 2 (purple)

- more accurate charging voltage (mainly changing the 60 kWh calculation)

Thank you all for the invaluable input!

- S60 and S85 have the same drivetrain, but different batteries.

P85 has another, more powerful drivetrain.

- Motor specs (from Tesla website)

Power:

S60: 285 kW - S85: 285 kW - P85: 350 kW (WITHOUT taking battery into account = theoretic)

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

- Number of cells per battery (each cell has a capacity of approx. 12 Wh, rounded for simplicity's sake)

=> 60 kWh battery has about 5040 cells

=> 85 kWh battery has 7104 cells (confirmed information from Tesla)

- Battery is charged at supercharger at 4.2 V charging voltage per cell

* 60 kWh battery tops off at 352 V

=> 352 V / 4.2 V = 84 cells in series in a single bank

* 85 kWh battery tops off at 402 V

=> 402 V / 4.2 V = 96 3.6 V battery cells in series in a single bank

- Number of banks per battery

* 60 kWh battery has 60 banks of 84 cells

* 85 kWh battery has 74 banks of 96 cells

- Maximum discharge current is 12.5 A per cell (based on 2) and 7))

* 60 kWh

=> 12.5 A per bank of 84 cells

=> 60 x 12.5 A for 60 kWh battery = 750 A

* 85 kWh

=> 12.5 A per bank of 96 cells

=> 74 x 12.5 A for 85 kWh battery = 925 A

- Maximum discharge power at nominal cell voltage of 3.6 V:

* 60 kWh battery:

=> 3.6 V x 84 cells = 302 V

=> 750 A x 302 V =**227 kW*** 85 kWh battery:

=> 3.6 V x 96 cells = 346 V

=> 925 A x 346 V =**320 kW**

Comparison drivetrain power output versus battery power output:

* S60: 285 kW vs 227 kW (battery limited)

* S85: 285 kW vs 320 kW (drivetrain limited)

* P85: 350 kW vs 320 kW (battery limited)

**Conclusion:**

Optional information regarding energy loss in the battery due to the cells' internal resistance:

**S60 is limited by maximum battery discharge rate of 60 kWh battery**

**S85 is limited by maximum power of drivetrain**

**P85 is limited by maximum battery discharge rate of 85 kWh battery**

8) Power loss in battery cells (dissipated heat)

The internal resistance of a fresh battery cell is about 100 mOhm (0.1 Ohm)

=> S60: 750^2 x 0.1 = 56 kW

=> S85: (285 kW / 346 V )^2 x 0.1 = 68 kW

=> P85: 925^2 x 0.1 = 86 kW

9) Total energy usage in battery (power output + heat loss):

=> S60: 227 + 56 = 283 kW

=> S85: 285 + 68 = 353 kW

=> P85: 320 + 86 = 406 kW

References:

High Power Wall Charger - Actual DC Volts/Amps Going To Battery?

Battery facts?

Analyzing car efficiency at different power outputs (accelerations) | Forums | Tesla Motors

Model S Options & Pricing | Tesla Motors (may not be the same, depending on your country)

industrial.panasonic.com/www-data/pdf2/ACA4000/ACA4000CE240.pdf

Last edited: Sep 20, 2013