Can I cause any harm by switching from Drive to Reverese at < 5mph?

[ucmndd]

"There is no physical mechanical connection between the application of rotational force and the motor's output."

There is force against the wheels and ground. For a demonstration, hold the chuck of an electric drill and press the button. That force ripping both your wrists off just cost the battery/electrical source a small amount of energy. That force you experienced on your wrists would be transferred to the mounts holding your wrists in place if they were mounted stationary. That force can mitigated by torque limits/current limits on the motor so it will not apply all the current all at once to force that chuck to spin, but allow it to slow or give without ripping your wrist off the mounts.

Sure, of course. But if your foot is off the accelerator, or your finger is off the trigger on the drill and you change the direction of the rotation, what force is being applied? It’s not the same as trying to change gears in an ICE transmission that is always spinning.

I wouldn’t want to change the direction of a drill while it’s running any more than I’d want to do the same to an electric car with the accelerator pressed (though as you point out I’m pretty sure there are programmed torque limits in the car that that would prevent you from doing something truly stupid), but if there’s no current applied...

 

[csanders90D]

Unlike an ICE transmission, there's no physical parts that get moved around when you switch "gears" on a Tesla. The only thing you have done is to tell the computer whether the go-pedal is for requesting torque in the forward direction, or if you're requesting torque in the reverse direction. There's nothing wrong with driving forward while the motor is providing reverse torque, that's just regen braking. Why would regen suddenly become bad when you're under 5 mph?

If you're worried about slack in the gears, that would be an issue every time the engine changes torque direction (i.e. accelerate->regen->accelerate), and the tiny forces during a 3-point turn are nothing compared to regen on the freeway. So, unless Tesla made a huge mistake and this whole regen braking idea needs to be scrapped, you're not doing any harm switching gears while moving.

The only reason they have a 5 mph limit on switching gears is to reduce driver error. What happens if you're doing 70 mph and the shifter gets bumped? It's a safe guess that nobody intends to back up in that case, so it's better to just beep at the driver instead of surprising them with reverse torque.

 

[PACEMD]

This hasn't been a problem since the introduction of the retro encabulator.........

 

[Silicon Desert]

This is because we are kind of guessing at the accurate answer.
The prudent thing would be to do this as few times as we can.
Certainly will not do the driveline any good.

yes, good point. Actually I am having a hard time understanding why some folks want to "intentionally' do this. I can understand doing it accidentally. If doing it intentionally, then it seems they have a bigger problem with time management that 2 seconds might be lost

 

[Silicon Desert]

I'd also like to think if there was risk of any harm, Tesla would not allow it. They specifically woite the software to allow a Reverse to Drive change at less than 5mph and I don't think they would have done this if there was any issue.

That is a good point I haven't considered. Then again, they also wrote the software that still lets us run into a brick wall

 

[Silicon Desert]

This hasn't been a problem since the introduction of the retro encabulator.........

huh ! Gee I am glad he doesn't come to any of my parties. We would all fall asleep listening to him.

 

[PACEMD]

huh ! Gee I am glad he doesn't come to any of my parties. We would all fall asleep listening to him.

Sorry, tl;dr.......

 

[⚡️ELECTROMAN⚡️]

Actually I am having a hard time understanding why some folks want to "intentionally' do this.

Because we can and it doesn’t hurt anything. I’m guessing applying the brakes and bringing the car to a complete stop, before shifting into drive, causes more wear than using an electromagnetic field to do basically the same thing.

 

[PhilDavid]

Because we can and it doesn’t hurt anything. I’m guessing applying the brakes and bringing the car to a complete stop, before shifting into drive, causes more wear than using an electromagnetic field to do basically the same thing.

So the expert consensus is it is safe to switch between R and D < 5MPH. Right?