Dual CT running on one motor

[RonM]

How would running a dual CT on one motor affect the range while highway driving, no stop and go? That is assuming one can disconnect a motor so that it is nothing but dead weight.

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[CyberDingo]

RonM... I had wondered about that too.
A friend had a Honda CRT, and it had that system.
I had driven it as a test, and you could feel the take-up from 2 to 4 wheel drive. It did get good mpg's.

 

[Crissa]

Tesla already does this. Based upon the current driving mode and demand for power, it uses or spins the motors as needed.

They actually use the different motors to gain different torque profiles, too, so that the most efficient coil can be used to extend the range of the vehicle.

-Crissa

 

[CyberDingo]

Interesting, thanks Crissa.

 

[CompMaster]

Like the new Raven S/X that uses the new efficient but powerful motor from Model 3 in the front. Leaving the previous power hungry and powerful motor in the back. Best of both worlds, always innovating and bring straight to customers the best of the best fast. Compared to waiting for others to catch up.

https://www.motortrend.com/news/tesla-raven-powertrain/

 

[Ehninger1212]

Tesla already does this. Based upon the current driving mode and demand for power, it uses or spins the motors as needed.

They actually use the different motors to gain different torque profiles, too, so that the most efficient coil can be used to extend the range of the vehicle.

-Crissa

If I'm not mistaken, they also have different gear ratios front and rear.

 

[Crissa]

If I'm not mistaken, they also have different gear ratios front and rear.

I believe these are static, though, so they don't really change the calculation. Just let the motors operate at a lower rpm than they would otherwise (unlike my Zero, which has a top speed seriously capped by the direct drive).

-Crissa

 

[Ehninger1212]

I believe these are static, though, so they don't really change the calculation. Just let the motors operate at a lower rpm than they would otherwise (unlike my Zero, which has a top speed seriously capped by the direct drive).

-Crissa

Right, in the M3P the rear motor is geared more for that performance low end grunt, with the front motor geared more towards high speed and highway driving.

 

[alan auerbach]

Right, in the M3P the rear motor is geared more for that performance low end grunt, with the front motor geared more towards high speed and highway driving.

Would have thought that rear drive would be for normal use, and the front would be added only when called for -- because it's tricky to design connections that both power and steer, as well as last without failing, wearing, or needing more maintenance than drive wheels that don't steer.

 

[ajdelange]

How would running a dual CT on one motor affect the range while highway driving,

It would reduce it to 0. If a motor fails in a Tesla I believe they will let you creep a few yards (enough to get to the side of the road) and then shut down. For reasons I don't understand Tesla will not allow its motors to be driven passively i.e. you cannot tug tow a Tesla vehicle and are strongly warned against doing so in their manuals.

Obvious question is what happens in a Rivian which will allow tug towing and even using this to charge the battery in case a motor fails. I asked this of them and was told they would have to research the answer and get back to me. I'm still waiting for an answer.

In the X there is an induction motor in the rear favored when you are accelerating and a more efficient synchronous motor up front for cruise.

 

[larryboy31]

It would reduce it to 0. If a motor fails in a Tesla I believe they will let you creep a few yards (enough to get to the side of the road) and then shut down. For reasons I don't understand Tesla will not allow its motors to be driven passively i.e. you cannot tug tow a Tesla vehicle and are strongly warned against doing so in their manuals.




I was hoping that the CT would be designed so that one could get home on any functioning motor. Seems to me that if you could pull a circuit breaker on the malfunctioning motor (motors) and flip another switch so that it could not charge the battery when it was being driven passively all would be well. Perhaps there are other reasons that this is not a good idea. I am sure someone will be willing to list several.

 

[FullyGrounded]

The problem with some of this, splitting of purposes won't help in off-road situations. If crawling or climbing or really anytime, you need the grunt at each wheel, though more to the wheel/s having the most positive grip and weighting. But, this won't always be fore or aft, nor right or left. So, all equally amazingly capable is always best, and very much preferred. Let the computer mess with, "If I shut down this motor or this combination of motors, range improves by "x"". I'm good with that. peace

 

[larryboy31]

The problem with some of this, splitting of purposes won't help in off-road situations. If crawling or climbing or really anytime, you need the grunt at each wheel, though more to the wheel/s having the most positive grip and weighting. But, this won't always be fore or aft, nor right or left. So, all equally amazingly capable is always best, and very much preferred. Let the computer mess with, "If I shut down this motor or this combination of motors, range improves by "x"". I'm good with that. peace

So if you are off road and a motor fails you will be fine with being able to move the car a few feet and then have it shut down all travel. I think even the most rabid off roaders would rather be able to drive (back up) to a point where they were near water, close to a road, in the shade or sun, where they could get cell service or what ever would make the time until they could get their CT repaired the most comfortable.

 

[Ehninger1212]

Would have thought that rear drive would be for normal use, and the front would be added only when called for -- because it's tricky to design connections that both power and steer, as well as last without failing, wearing, or needing more maintenance than drive wheels that don't steer.

Yeah I'm not sure, I have only had this explained through articles. I'm not sure what the actual source of the information is. For all I know it could be the other way around.

 

[myco.rrhizae]

How would running a dual CT on one motor affect the range while highway driving, no stop and go? That is assuming one can disconnect a motor so that it is nothing but dead weight.

I remember back when they revealed the dual motor variant of the model S and bragged about how electric awd is different from ICE awd in that ICE looses efficiency with powertrain complexity by having awd but electric gains efficiency by having awd, because they can seemlesly control torque vectoring for optimum power distribution among wheels without loosing power to the friction you would have in a 4wd gearbox.

So to answer your question, I think that the active dual motor will use less kwh per mile than the single motor, but a single motor will use less kwh per mile than dual motor with one motor inactive because of the dead weight.

why would you want to do that anyway?!