The Tesla Model 3 “P” version has 500 HP available at the battery but uses only 95% of it - we do the math
Our calculations show that the P AWD version of the Model 3 requires 471 hp out of the battery and into the drive unit. Based on Electrek hacked number the battery is good for 500 hp so we have 5% margin. Leaving room for additional performance.
As we discussed in “Has Tesla changed how it controls the front and rear motors in Model 3” the computer model has a cruise gear ratio in the back and an acceleration gear ratio in the front, which is opposite of the Model S. The primary reason being that the Tesla rear motor is now a permanent magnet motor, which is more efficient than an induction motor. It seems logical to use the more efficient motor as the cruise motor. See the bottom of the above slide for the gear ratio’s we ended up with. Our models also predict the same range for all three versions of Model 3- matching spec.
Detailed discussion of our math analysis
We have modeled quite a number of different EVs by now starting with the Tesla truck, Tesla gen 2 Roadster, BoltEV, Porsche Mission e, and Model S P100D. One thing we have learned is that the battery is the driver when it comes to estimating a vehicle's performance. The problem is, when these EV manufacturers mention how much power a certain vehicle has, they don’t always quote the same number. Sometimes they will throw out some big number that the motor is good for, sometimes not, but more times than not the battery ends up being the pinch point. We saw that in our analysis of the Tesla Roadster. It’s usually a power limitation of the battery pack that drives the performance numbers.
We were trained from the ICE days to look at power out of the engine, so it’s just natural to think of EVs in terms of output from the electric motor (drive unit). We must retrain ourselves to think in terms of battery power, not motor power.
Here’s our estimate of the drive unit outputs for the Model 3. We estimate that the total drive unit output power delivered to the wheels of Model 3 “P” AWD at 410 hp. Next down the ladder the AWD “non-P” is estimated at 330 hp, the RWD model now shipping to customers at 271 hp and the SR RWD at 220 hp.
Of course, torque is where it’s at for EV’s. That is where we get the advantage over an ICE. An EV has torque all the way to zero RPM, an ICE does not.
Coming off the line is where the ICE has trouble, then it needs to shift which slows it down even further. In the Car and Driver article on the BMW M3, the driver could not get below a 4-second 0-60-time, even though it is rated at 3.7 seconds (versus 3.5 for Model 3 “P” AWD).
Of course, we used motor maps in our analysis. We’ve included the motor maps for the “P” AWD Model 3. Notice there are 2 break points in the power torque curves. Breakpoint 1 is where we transition from constant torque to constant power. Breakpoint 2 we transition from constant power. We let the power fall off at a specified rate.
Of course, there’s more than just motor maps. There’s a fairly extensive list of constants that need to be input as well.
Here’s an example input sheet:
Even after all this, it is still just a computer model and it has its limitations. There’s always room for improvements and, as time goes by, more and more improvements get added.
Keith Ritter (HVACman) must take most of the credit for writing this spreadsheet. Keith knows the motors while I am more in the battery department. We volunteer all our time.
We are working on a math model of the Model 3 battery’s heat transfer performance. It’s right up Keith’s alley since he is a licensed HVAC engineer and owns his own business in Redding California- ME Systems. We hope to have some interesting comparisons of Tesla’s cooling methods versus the flat plate cooling method used by GM and the German manufacturers. Thanks for reading our articles. Stay tuned.
George and Keith