Regenerative braking on icy roads

[tm1v2]

@mikemarmar Thanks for putting up your money to test this and sharing the results, that's awesome!

Next question about these buttons...can you tell if they can set regen higher than the standard amount? After all that rep did say "100% to 0% like on the performance model." In M3P Track Mode v2 100% regen is actually much stronger than normal driving mode regen, as I've recently learned and experienced. Not what you want for snow and ice of course, but it's great for tearing up dry twisty roads.

(Honestly I'm guessing that isn't possible, except maybe in an actual M3P with Track Mode v2 enabled, but I'd be really excited if I'm wrong and you can get the extra strong regen in any 3 or Y!)

You turned regen off entirely... How? I thought Tesla removed the ability to turn off regen?

Scroll up to Regenerative braking on icy roads

 

[pbcsd]

@mikemarmar


Scroll up to Regenerative braking on icy roads

That's interesting (and a bit frightening that someone can easily hack into it!).

I still don't understand why Tesla just doesn't make it an option as they do or used to with the S. Only time folks would use it is during the winter storm months.

 

[rjpjnk]

Still waiting for our first snow here with the Model Y. How well does the MY recover on its own when regen kicks in and causes rear wheels to lock up? In that half second as mentioned above before the car realizes it’s sliding and stops regen does it seem unsafe or reasonably well controlled? Just wondering which approach is safer overall, disabling regen or just learning to work with the car as is.

 

[OxBrew]

With good snow tires on packed snow over ice, I have not been able to fishtail at all. 30mph, in a corner, full lift off, car just slows down. I can feel the traction control adjusting things to keep it straight, all feels fine.

On a full throttle launch in the snow, after several straight line, I was able to kick out the rear end for maybe 1-2 ft by turning before it straightened out. Seems way more composed than our outback it the same situations.

It's actually amazing, just goes where you ask it to.

(all this on empty streets late at night, no one around. Never fool around when it's unsafe)

 

[UncleCreepy]

With good snow tires [...]

^ That right there is the key.

 

[rjpjnk]

With good snow tires on packed snow over ice, I have not been able to fishtail at all. 30mph, in a corner, full lift off, car just slows down. I can feel the traction control adjusting things to keep it straight, all feels fine.

On a full throttle launch in the snow, after several straight line, I was able to kick out the rear end for maybe 1-2 ft by turning before it straightened out. Seems way more composed than our outback it the same situations.

It's actually amazing, just goes where you ask it to.

(all this on empty streets late at night, no one around. Never fool around when it's unsafe)

Sounds very impressive. The Outback is a tough car to beat in the snow in my experience. The traction control in these Teslas seems amazingly good. I was hoping it might be able to figure out how to drive in snow without having to manually turn the regenerative braking off. Sounds like this has been the case for you. Have you tried turning the regen off? If so, which do you like better?

 

[OxBrew]

Sounds very impressive. The Outback is a tough car to beat in the snow in my experience. The traction control in these Teslas seems amazingly good. I was hoping it might be able to figure out how to drive in snow without having to manually turn the regenerative braking off. Sounds like this has been the case for you. Have you tried turning the regen off? If so, which do you like better?

I have a Y, so can't turn it off. The regen in my case was partially disabled, maybe 3 dots, so not really apples to apples, if I'm honest (cold outside, SOC about 60%).

But really, in normal snow driving, you learn in about 100 ft how to feather the regen with your foot, so you can add as much as you want any time, from 0- full regen.

Really, if you're complaining that when you lift off suddenly on an icy downhill corner at 35, and the car gets squirrely, you're driving wrong. That's like saying your manual awd car got too loose when you downshifted from 3rd to 1st at 35 in the same corner. We would all point and laugh.

Don't lift suddenly in icy conditions. Feather it as needed.

Our previous cars since 2005 have been an 05 Outback, 12 Outback, 14 Outback, and an 04 Forester we had the whole time too, still have it. All with Blizzack snow tires, snow on the ground from Nov to April (on and off).

Besides the Y, Subarus are hands down the best snow cars, IMO. Friend of mine also previously a Subaru fanatic, has had his Y for 3 years in Spokane (maybe the first one here). He says the same thing.

 

[JNM67]

You turned regen off entirely... How? I thought Tesla removed the ability to turn off regen?

Read the full thread. He bought some buttons from a third party supplier that enable this.

 

[PNWLeccy]

Friend of mine also previously a Subaru fanatic, has had his Y for 3 years in Spokane (maybe the first one here).

The Model Y started production in March 2020 so I wouldn’t trust this so-called friend since he’s either a liar or very bad at math. Haha

 

[OxBrew]

The Model Y started production in March 2020 so I wouldn’t trust this so-called friend since he’s either a liar or very bad at math. Haha

Ok, so he said he's had Teslas for 3 years. I was confused. Got his Y in June 2020 I think, IDK.

We were just talking about Teslas in the snow last night at dinner. Convinced another friend of ours to replace his Outback with a Y.

 

[PNWLeccy]

Ok, so he said he's had Teslas for 3 years. I was confused. Got his Y in June 2020 I think, IDK.

We were just talking about Teslas in the snow last night at dinner. Convinced another friend of ours to replace his Outback with a Y.

I’ve had my 2018 M3 LR RWD for 3 years and made about about 25x trips to Stevens last year but it was not great.

On the road up I felt fine with the exception of some rear movement but I grew up driving in New England so that didn’t bother me. I drive with full regen on despite having the option to reduce it and I think it’s fine as long as you feather it like lots have mentioned.

However, in the snow-packed parking lots, even with tire socks and using slip-start, I needed to get a push 5x times just to get going. Maybe that was due to the RWD and not getting enough traction but I was surprised at how bad it was. It cuts power and you just cant move at that point. I’m hoping the MY dual motors solves that issue.

 

[mikemarmar]

Got to play around in the snow again last night. This time it was a twisty, hilly, packed snow road (dirt road in the summer) with lots of ruts, washboard and some smooth icy sections. The car handled impressively well. On the downhills it was a bit more wiggly than my old '04 subaru impreza wagon, which could just come down to different tires or maybe because the tesla is so much heavier. On the uphills the car was very good, better than the old subie. It could crawl up crappy washboarded snow at low speed without any problem. It felt easy and I didn't have to worry about rallying speed to get up steep sections.

I also tested out regen behavior on the snow road at low speeds and it felt fine, very solid. Really, the only place that regen on snow scares me a bit is at higher speed (40-50 mph) on the highway.

Also, I was watching the app that came with the s3xy buttons (it displays power and torque on each motor in real time) yesterday while my wife was driving and saw something interesting. When driving around at low speed, regen is mostly front motor biased. At higher speeds regen is entirely on the rear motor. I don't really know why they programmed it that way but it could explain some of the behavior people have experienced.

 

[mikemarmar]

However, in the snow-packed parking lots, even with tire socks and using slip-start, I needed to get a push 5x times just to get going. Maybe that was due to the RWD and not getting enough traction but I was surprised at how bad it was. It cuts power and you just cant move at that point. I’m hoping the MY dual motors solves that issue.

I experienced the exact opposite in my dual motor Y. It is amazingly good at getting started in the snow and crawling up steep inclines at low speed.

 

[PNWLeccy]

I experienced the exact opposite in my dual motor Y. It is amazingly good at getting started in the snow and crawling up steep inclines at low speed.

Good, I'm hoping the the dual motor will help mitigate this in the new MYLR coming soon. Although I hear the stocks 19" conti's are not very good in the snow.

 

[UncleCreepy]

Although I hear the stocks 19" conti's are not very good in the snow.

You heard correctly. No all-season or summer tire is very good in the snow.
I yet have to find a winter tire, no matter how cheap, that isn't way better in the snow than an all-season or summer tire.

 

[mikemarmar]

Next question about these buttons...can you tell if they can set regen higher than the standard amount? After all that rep did say "100% to 0% like on the performance model." In M3P Track Mode v2 100% regen is actually much stronger than normal driving mode regen

In my testing, no I can't set regen higher than the standard 100%. Maybe that is just a performance model thing since the rear motor is higher power (and thus higher potential regen power).

 

[boredwitless]

I was recently able to test our our MYLR on snow, which is fitted out with winter tires for the season (Continental WinterContact TS 860s on Gemini wheels). As for some of the others posting here, I found it handled impressively well – I had to push very hard to unsettle it.

However,my experience when hitting a couple of patches of ice was quite different (also with the winter tires), especially one which was unexpectedly on a corner of a twisty forest road. Both times the car had one or two seconds of instability and fishtailing before coming under control and settling down. In neither case was I slowing down strongly under regenerative braking, so I'm guessing that this was more to do with the rear wheel drive bias? I'm used to FWD cars, which behave quite differently.

 

[sdoja3]

Ice storm here in Chicago the last 24hrs. First time driving on legitimate icy freeway 80/94 in IN & IL in my 2022 M3LR.

Unfortunately can confirm (atleast for me) that the regen braking was absolutely an issue on the ice today. Normally in a ICE vehicle the coasting on icy roads avoids any sort of lock up or loss of traction. When you hit the brakes is when you tend to lose control and start to slide on ice and get sideways. If I could, I would choose to turn regen braking off in icy conditions after today. Wasn’t a comfortable drive in icy Midwest roads.

 

[tm1v2]

@sdoja3 Time to try those buttons from up thread? Let us know if the regen adjustment works on your car!

 

[Duncan Parks]

I have had more than one close call with this issue. It is literally criminal that there is no way to disable regenerative (read: uncontrollable) braking when conditions demand it. Hopefully it won't take a class action lawsuit for Tesla to move this to problem to the front burner.

When you let off the accelerator in slippery conditions and the immediate braking initiates a slide/hydroplane all you can do is pray.

I have also had problems with the regen brake force distribution in snowy conditions. Here's the problem: regen brake force is distributed like driving force - rear-wheel biased. That's why you put the chains on the rear wheels! However, this is exactly opposite to decades of automotive engineering wisdom, namely that braking should be a bit front-biased, so that you get understeer if you brake to the point of locking wheels (which means you go straight instead of spinning the car). If you don't believe it, just look at the size of rotors and calipers on the front and rear of pretty much any respectable car. I would guess that the friction brakes on the MY are also front-biased.

If you pull your foot off the accelerator too quickly in snowy (or other low-traction conditions) and regen braking kicks in with any real force, the rear wheels slip first and the back of the car slides around until traction control saves it. That's stupid on its face, but even stupider because there is a drive mode that fixes the problem: "Off-road assist." In that mode, the drive and regen braking force are more evenly distributed, and it utterly solves the problem...but traction control is also defeated. So you can get a distribution of regen brake force that maintains traction in slippery conditions...but only with the compromises that come with off-road assist. Nonetheless, until Tesla fixes this problem, that's the best solution for a driver that knows how to handle a car in snow.

So Tesla...you already have the solution to this problem. Simply make *all* regen braking use the brake force distribution in Off-road assist. It's so frustrating that such a sophisticated car would include such a basic engineering mistake. You can keep your boombox and lightshow; give me a car that handles properly in the snow.