Tesla Model 3 Dual Motor AWD - 4x4 test on rollers

[FraKam]

Hello Everyone,

I would like to share video with you about Tesla Model 3 AWD for all people considering how traction is working.
This is not a super proper test, but can show how the car handles with no traction.

 

[bhzmark]

not sure what to conclude from that. i guess that it takes longer than we might think to get power to the one wheel w traction?

 

[destructure00]

It's a lot better than the other cars I looked up doing the same test...

 

[Nuclear Fusion]

Ha ha! Most 4WD vehicles struggle with the tests, often failing at the point of only one wheel with traction.
Another area that electric trumps fossil!

 

[FraKam]

This test shows how traction on every wheel is working, first we test no traction on front wheels and check if car can handle that, than on back wheels, diagonal and the final testing: 3 wheels no traction and the car needs to handle traction only on 1 wheel

Look how this looks in Toyota RAV4

 

[TORQU3]

This test shows how traction on every wheel is working, first we test no traction on front wheels and check if car can handle that, than on back wheels, diagonal and the final testing: 3 wheels no traction and the car needs to handle traction only on 1 wheel

Look how this looks in Toyota RAV4

Wow, that is eye opening.

 

[M109Rider]

This test shows how traction on every wheel is working, first we test no traction on front wheels and check if car can handle that, than on back wheels, diagonal and the final testing: 3 wheels no traction and the car needs to handle traction only on 1 wheel

Look how this looks in Toyota RAV4

Wow. Total fail for the Rav 4.
Yikes.

 

[Daniel in SD]

This video shows that the Model 3 is RWD at low throttle inputs until it senses slip and then transfers power to the front. They should really have true AWD mode for winter conditions that sends equal torque to all wheels.

 

[SammichLover]

This video shows that the Model 3 is RWD at low throttle inputs until it senses slip and then transfers power to the front. They should really have true AWD mode for winter conditions that sends equal torque to all wheels.

That'd require a lot of duty cycle on the brakes. Given that it will do it in a relatively short time as show in the video, in seconds, this seems a decent trade-off to potentially excessive brake wear/heating in poor traction conditions.

If I'm driving in crappy conditions all I really care is I don't have to get out and shovel (away from the wheel, or gravel under the wheels, or whatever). This looks like it'll do that for some pretty bad conditions. The rest is on me to drive appropriate speeds to maintain enough control.

If you were looking to rally race or something that would be a different matter, I suppose.

 

[ZOMGVTEK]

The brakes are only used to help transfer power across an axle since the differential is open. You don't need to touch that logic with a dual motor setup, just push similar power to both motors across all throttle positions. It would ding efficiency a moderate amount id imagine, so maybe that's whats putting them off. It would be technically super easy presumably, and it would be nice to combine it with a loose surface optimized regen among other winter specific features.

 

[compu85]

This video shows that the Model 3 is RWD at low throttle inputs until it senses slip and then transfers power to the front. They should really have true AWD mode for winter conditions that sends equal torque to all wheels.

They changed the software at some point - now when its cold out it uses the front motor all the time.

 

[Nogasmn]

The fact that Tesla can make changes on the fly with over the air updates is amazing. Even more happy with my purchase now.

 

[SwedishSTIle]

Its not actually that impressive and I fully expect it to be easily capable of those challenges.

Any Haldex systesm Gen 3 and up (VW etc), Audi Quattro, Subaru symmetrical and several others will be capable of completing all of those tasks. I am guessing that BMW's X drive and MB's 4Matic should also complete the challenge, though maybe with more fanfare than the Haldex, and the two symmetric systems. Not to mention any real 4X4 system, especially with any differential locks.

 

[Nogasmn]

While it my not be impressive, I am looking at it from the traditional mechanical 4x4 system VS an electrical 4x4 system. My previous car, Toyota Rav4 AWD, did very well in the snow and I was apprehensive getting the 3 due to not being sure how it would handle the snow. But the 3 handled it's first season great, however to be honest on the heavy snow days the 3 stayed in the garage and we took the mini-van.

 

[ZOMGVTEK]

Yeah, It's certainly not impressive at all. It performs worse than is technically possible by a considerable margin. It performs about as well as a high end modern AWD system that's well tuned, but they have a huge advantage with two motors on separate axles.

I assume they don't think it matters all that much, and its biased conservatively to minimize brake wear and maximize efficiency. Reasonable design goals, but i'd imagine they can do a fair bit better. At least they're likely to give everyone an update if they do improve it with time.

 

[MentalNomad]

This video shows that the Model 3 is RWD at low throttle inputs until it senses slip and then transfers power to the front. They should really have true AWD mode for winter conditions that sends equal torque to all wheels.

The video actually shows power going to front wheels immediately - but it's not sending enough torque to drag the car over the rollers (to lift the rear end) until after it senses the rear slip and increases the front torque more.

Take a closer look, and compare the one-wheel tests for front/back action to compare to the timing you see in the rear-wheel test.

 

[Daniel in SD]

They changed the software at some point - now when its cold out it uses the front motor all the time.

I hadn't heard this. It was definitely RWD until slip was detected when I drove in January. Air temp wouldn't be a great way to do it in California since it can be 50 degrees out with snow on the road.

That'd require a lot of duty cycle on the brakes. Given that it will do it in a relatively short time as show in the video, in seconds, this seems a decent trade-off to potentially excessive brake wear/heating in poor traction conditions.

If I'm driving in crappy conditions all I really care is I don't have to get out and shovel (away from the wheel, or gravel under the wheels, or whatever). This looks like it'll do that for some pretty bad conditions. The rest is on me to drive appropriate speeds to maintain enough control.

If you were looking to rally race or something that would be a different matter, I suppose.

3 open diffs and no computer trickery gives you equal torque to all the wheels (that's what my Subaru had). They just need to send equal torque to both motors which they don't do for efficiency reasons, hence the need for a special mode.
Rally racing is fine since when you really stomp on the throttle you do get torque to all the wheels. The problem is at light throttle on slippery surfaces the car tend wiggle like a snake. Power to rear wheels -> slippage -> power to front wheels -> slippage -> power to rear wheels -> ...

 

[Daniel in SD]

The video actually shows power going to front wheels immediately - but it's not sending enough torque to drag the car over the rollers (to lift the rear end) until after it senses the rear slip and increases the front torque more.

Take a closer look, and compare the one-wheel tests for front/back action to compare to the timing you see in the rear-wheel test.

I don't see it. Look at the test where the front wheels are on rollers. There is zero torque to the front wheels, they don't slip at all. They should have done a test with all the wheels on rollers. It would be much more clear. A car with a symmetrical AWD system would just spin all the wheels. The Model 3 would spin the rear and then the front and then probably oscillate between the two.

 

[gbrgbr]

the poll should have offered the option of "both"

 

[SammichLover]

A car with a symmetrical AWD system would just spin all the wheels.

You're asking for 4x4, not AWD.

Because they control the bias via different motors, there isn't that differential in the middle that a single engine vehicle has that creates dynamic evening out so they do it programmatically by not bothering with the front motor at times (for efficiency reasons) until there is a need.