Dual CT running on one motor

[Crissa]

Would have thought that rear drive would be for normal use...

The normal use of low end torque is acceleration?

why would you want to do that anyway?!

...Because when you're not accelerating, you don't need to power the extra torque.

Even a quad-motor Rivian has a simpler powertrain than any AWD ICE configuration.

-Crissa

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[Diehard]

"I was hoping that the CT would be designed so that one could get home on any functioning motor. “

it looks like this guy went home only on rear motor:
https://forums.tesla.com/discussion/145046/front-drive-unit-failure

 

[Crissa]

it looks like this guy went home only on rear motor:
https://forums.tesla.com/discussion/145046/front-drive-unit-failure

The car was drivable in sort of a limp mode, ...

That's cool ^-^ Tho driving in limp mode is no fun.

-Crissa

 

[TI4Dan]

I am assuming that Tesla's has active stability control and it would be better if both motors stayed active to have better control of CT AWD( dual and tri motors) during varible road conditions. When I have used A Better Route Planner it does not make a difference between single or dual motor CT as far as WH/mile goes.

 

[ajdelange]

The car can independently ask for as much torque as it wants from each motor. Thus in any given situation it will "torque vector" control for stability and economy. Economy does not mean running one motor or the other. It means blending the two (or three) as required for optimum performance.

ABRP does not distinguish between the configurations in terms of consumption because it does not have the information it needs to do so for any of the models at this point in time. it has to use an estimate based on its experience, intuition and engineering experience.

 

[Crissa]

Yeah, the lead foot probably affects range more than the number of motors from ABRP's pov. Though you can put in your average efficiency manually in some versions of the app.

-Crissa

 

[Diehard]

That's cool ^-^ Tho driving in limp mode is no fun.

-Crissa

I would have loved to know the downsides of the limp mode so I can judge for myself how long I wish to drive that way. Does anyone know if, how and how much technical info Tesla shares?

 

[Daweism]

I mean if u can turn off the front motor and redirect all power to the rear motor, that could have its uses.

 

[Crissa]

Limp mode varies. Usually it means capped speed and torque, sometimes it means flashers on. Teslas have a few layers of it before they become a lump, the last one being 'I won't move more than 5mph so you can tow me'.

-Crissa

 

[TI4Dan]

The car can independently ask for as much torque as it wants from each motor. Thus in any given situation it will "torque vector" control for stability and economy. Economy does not mean running one motor or the other. It means blending the two (or three) as required for optimum performance.

ABRP does not distinguish between the configurations in terms of consumption because it does not have the information it needs to do so for any of the models at this point in time. it has to use an estimate based on its experience, intuition and engineering experience.

I thought The dual motor would have a little higher power consumption than the single motor. When I discovered that the powered used per mile was the same on ABRP figured what do I know about the actual WH/M, glad you mentioned it.

 

[Diehard]

I am assuming that Tesla's has active stability control and it would be better if both motors stayed active to have better control of CT AWD( dual and tri motors) during varible road conditions. When I have used A Better Route Planner it does not make a difference between single or dual motor CT as far as WH/mile goes.

If you are on a 6 hour highway trip, the system probably could relax a little more with one of the motors since there are still some mechanical loss associated with getting power to the wheels. and since it is all electric, it can kick in at any time with no delay. Of course this is all an assumption. I wonder if there are any current dual motor owners can see on display and share how the motors behave when you are cruising on a highway.

 

[ajdelange]

I drive a dual motor X and believe the synchronous motor to be in the front and the induction motor to be in the rear. The car gives no clues as to which motor is emphasized when but common sense says that the more efficient PM motor would carry most of the load in cruise whereas the torque brute induction motor would handle demands for acceleration, especially off the line. About all I can say is that Tesla squeezed an extra 55 miles of range out of the X battery by going to 1 PM and 1 induction (from 2 induction) and tweaking the software that controls them.

Note that the CT will have, presumably, only PM motors.

In one of the Rivian videos I did spy for a second a display that clearly showed the amount of power going to each wheel. I'd certainly love to have that but I'm pretty sure Tesla won't give us that and I rather doubt it will be available in the production Rivians either.

 

[Bill906]

About all I can say is that Tesla squeezed an extra 55 miles of range out of the X battery by going to 1 PM and 1 Synchronous (from 2 synchronous) and tweaking the software that controls them

I believe you I misspoke here. I think you meant induction (or asynchronous) where you say synchronous. But I do not know the history of the MX to know for sure. PM motors are synchronous motors.

 

[Gvardaman]

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.

Well, if you are pushing/pulling a motor that is engaged, it starts generating power. So, if a Tesla fails and needs to be towed (or one motor out of two fails) and you start rolling that “bad” motor, the electricity generated needs somewhere to go. If it pumps back into your battery, what happens when it gets to 100%? Or if it is “charging” too fast? The car may be (most likely will be) powered down, so the battery management system and computer can’t help. Also, even if it were on and monitoring, while the driver is in the cab of the tow truck or in jail, whatever, what would the car do to warn that is was getting too hot/overcharging, etc.? Maybe it could turn on the headlights to drain off electricity, but that’s not enough. Besides, if the car is damaged and being towed, what if the headlights are broken?
without knowing exactlywhat the situation is, is is pribably too much of a liability to risk a flat tire tow turning into a a car fire.
Another thing I would consider is the motor itself,spiningalong, with possible damage.if it shut off or was stopped, it is possible that foracing it to move would cause far more damage.

 

[CyberDingo]

In the doco, "Long Way Up", they tow / charged the Rivens when they couldn't get to a charger.
I thought, GREAT, now that may come in handy!

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