"Rear Engine Off", "Car Shut Down" - Our Reader's Adventure and Story of Two Model 3 Engines • ELECTROMAGNETICS

"And it's all about driving a Tesla," a Reader who bought a Model 3 Performance last November wrote to us. While charging, his car started displaying the message “Rear Engine Off. You can drive" and "Car turns off". On D it was impossible to turn on, it was impossible to go. Tesla will go to Warsaw on a tow truck.

Is it only possible to drive a single engine in a Tesla Model 3 in exceptional circumstances?

Table of contents

• Is it only possible to drive a single engine in a Tesla Model 3 in exceptional circumstances?
  • Is it possible to drive a Tesla Model 3 all-wheel drive after one engine failure?
  • What about our reader's Tesla Model 3?

Our reader has a Tesla Model 3 Performance, he traveled 2019 kilometers since November 17. Today he joined the Superchager in Rzeszow. Back in the car, he found two messages on the screen, alternating every 5 seconds:

• The rear engine is off. You can go

  Vehicle power may be limited

• The car turns off

  STOP. IT'S FREE.

Despite the "ride", the car could not be switched to D-mode, so there was no question of driving. And now we come to the essence, that is, requests from the header.

Is it possible to drive a Tesla Model 3 all-wheel drive after one engine failure?

Well, in a Tesla Model 3, the two motors are not equivalent to each other. The one in the back contains the electronics that control the operation of the one in the front of the car, assuming the car has four-wheel drive. So if the problem is with the rear engine, chances are good that the car will be running on the front engine.. Another thing is when the problem comes from the front - then there is a chance that we will get to the destination on the rear engine, if the problem is not in the "gear breakage" category.

There's something else that gets in the way of driving the front engine with the rear engine off: physics.. The Tesla Model 3 AWD uses an induction motor at the front (with electromagnets) and a permanent magnet motor (PMSRM) at the rear.

> Tesla Designer Explains Reasons for Switching to Permanent Magnets in Tesla Model 3

The absence of voltage at the contacts of an induction motor means that we are dealing with simply rotating masses of metal, nothing is induced in them, the motor has minimal resistance. If the wheels spin such a motor, nothing is induced in the chain, there is no risk of generating energy with which you do not know what to do.

The situation is quite different in the case of a permanent magnet motor. There, a strong magnetic field is constant - because it is created by permanent magnets, not electromagnets - so even an "idle" motor will generate voltage in the circuit (source). Spinning motor wheels cause a voltage problem at the motor terminals. Voltages that you don't know what to do with and that can cause further damage to your circuit.

Theoretically, movement with such a motor is possible after it is completely turned off, i.e. physically disconnected from the propeller shafts so that the engine does not rotate. However, we are not sure if this is possible at all. We do not see a place in the Tesla Model 3 powertrain, such a clutch could be set so that the spinning wheels do not make the engine turn:

Rear powertrain Tesla Model 3 (c) Ingineerix / YouTube

What about our reader's Tesla Model 3?

The failure didn't seem to satisfy him, but he was surprised by the fast service. His car was identified by the phone number, he did not need to dictate the VIN, he only needed to confirm the color and year. Dictation can be confusing for a consultant calling from the Netherlands and speaking English.

Tesla employee remotely entered the car and made a quick diagnosis. Unfortunately, remote repair was not possible, so a tow truck was sent for the car from Warsaw. Tesla will go to the service, and our reader will receive a replacement car.

We will keep you updated on the progress of this case.

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