VERY close call today on snowy/icy Interstate 40

[mwulff]

First of all as a resident of a snowy country let me say that I am happy to hear that you and your family are all right. That could have gone badly wrong. Second throw those Primacy tires in the trash where they belong.

All-Weather/Year tires are a scam. They are not great summer tires and they don't work well in snowy conditions. My advice would be to get Nokian WR A3's for winter (or Hakapalites if you live in really snow regions) and a nice summer tire for summer.

In snowy conditions you can set the amount of regen on the 17" display. I believe it is under controls -> settings -> driving.

Other than that: Nicely saved

 

[mspohr]

People without D always seem to want to diminish the performance of AWD. Having lived in heavy snow country for 35 years and driven a wide range of AWD cars,I appreciate their superior ability to stop,go and steer in all conditions. You may be happy with your RWD but I will always choose AWD for better performance in all conditions.

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As far as putting it in neutral, some have made this recommendation I have never done this and never felt the need. My D has always been solid in all conditions just like dry pavement. The stability control of the car does a superb job in all conditions (at least that has been my experience with the D.)... YMMV

My only extensive experience with RWD in snow and ice was about 45 years ago when I had a manual RWD and ended up in the ditch a few times. After that I learned to put it in neutral. One would think that Tesla stability control control would manage RWD regen but it may not. The D has excellent control.

 

[jerry33]

For winter here in Texas I put on Nokian WR-g3 (have a second set of wheels). They are severe service all-seasons, not the "Texas" all-seasons like the Primacy and almost all other all-season tires. You would have had a lot less drama. These tires are better than all but the best snow tires and don't melt when next week the temperature goes up. I've used the WR series tires in several cars and have been impressed with how they handle winter conditions.

 

[GSP]

AWD would have helped in this situation by allowing regen braking on the front wheels, instead of just the rear. It was oversteer due to rear wheel braking that caused the partial loss of control.

Also, it would be really nice if Tesla offered an option to select regen braking level with paddle "shifters" or multiple "D" positions on the shift lever. On my Volt I really like being to quickly apply or disable lift throttle regen by shifting between "D" and "L"

GSP

 

[EVSteve]

I've said before, I'll say it again. ALL cars with regenerative braking NEED a Snow/ice mode that disables regen and only uses friction braking! In a Volt it's easy to go back and forth between neutral but again the same problem exists.

 

[mspohr]

I've said before, I'll say it again. ALL cars with regenerative braking NEED a Snow/ice mode that disables regen and only uses friction braking! In a Volt it's easy to go back and forth between neutral but again the same problem exists.

I would think that this is something that should be handled automatically by the stability control. If antilock braking can sense wheel lock, it should also be able to sense wheel slipping on ice and snow.

 

[DFibRL8R]

After I had my moment I tested out regen in different situations to figure out if tracktion control would kick in. Nothing. The Model S doesn't seem to take regen into account when trying to keep the car on the road in slippery conditions. In all my tests the car started to fish-tail. Sometimes switching regen to LOW helps a little but not when it's just slippery. Regen will automatically reduce itself once the wheels rotate slower (regen is reduced with decreasing speed) but in most cases that's still enough to make the wheel slip.

David99, Interesting/concerning observation. I find it very hard to believe that Tesla did not engineer the car to detect loss of traction in BOTH regen braking and normal/friction braking situations. In either scenario, I would expect the car's TCS to very quickly sense the problem and work to correct it by variable application of braking, reducing power (or possibly even adding power in the correct scenario?) to the appropriate wheels to correct the slide. If power can be applied, I would also believe AWD would enhance this system by adding another option for the car to apply power in the front as an option to to regain control (despite what all the AWD haters keep claiming that AWD is only good for getting a car going in winter conditions). Your experience in your RWD suggests this system may not perform as I assume. I would like someone with more knowledge about how these TCS systems work to comment. Are they applying braking only or can the car automatically apply power as well to try to correct a slide?

 

[Cosmacelf]

Being able to disable regen entirely in bad conditions isn't as good as an ICE as you might think. An ICE has significant engine drag when you lift your foot off the accelerator. It obviously isn't as strong braking as regen low, but it is still there. Enough so that you can slow to a virtual stop when driving slowly on snow packed roads and "coasting" to a stop. A Model S in neutral, or with no regen will coast really, really well, and won't coast to a stop for quite a while. A Model S snow mode would be nice to have extra low regen...

Living in CA, whenever it just sprinkles snow in the mountains, they force you to put on chains. Which I hate, since they can give you less traction on slick roads. Anyone have experience with a good set of chains?

 

[Jaff]

Great post Todd.

We are all experienced in dealing with this issue in our ICE vehicles...in this situation, letting off the accelerator is now "human nature" due to our ICE vehicle experience...driving my Roadster through 5 winters (heavy, non-adjustable regen), imo, feathering the accelerator to a neutral position is the best thing to do.

Happy to hear that the OP got through this incident safely!

Glad you recovered.

You said you let off the accelerator gently--although in this case even if the pedal movement was very slow, the real question is how *much* regen did you allow to kick in? In a situation like that, probably 10 kW or perhaps less of regen would be the very most you'd want to allow--so you wouldn't want to allow much regen at all.

It's very likely this was just a patch of ice for which almost *any* amount of braking would have triggered the rears to break traction. Obviously, in such a situation it's probably a good idea to set regen to low and to be very careful about letting the pedal out extremely carefully, and not too far. Stay focused on keeping regen torque minimal, which is even more important than the rate at which the pedal moves.

Ideally, the split second you started to recognize that regen was causing you to lose traction, adding enough accelerator input to coast and just gradually slow down that way would have been the best solution. But given that you did break free, and although scary you managed to keep it under control, I'd say you did a good job given the circumstances.

Experiences like this help keep us careful the next time .

 

[AWDtsla]

"told you so". Black Ice and Regen: bad combo?

We can drive the car in cold climates != the car has been fine tuned for cold weather.

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AWD would have helped in this situation by allowing regen braking on the front wheels, instead of just the rear. It was oversteer due to rear wheel braking that caused the partial loss of control.

So instead of fishtailing you're just put into a basic slide? This is only minimally better.

 

[Doug_G]

You need to be NOT using regen in that situation. Push on the pedal a little. If you're not confident you can neutralize the acceleration, at least set Regen to Low while in slippery conditions. That will limit the impact of it.

 

[Matias]

I find it hard to believe, that Tesla wouldn't have fine tuned regen to work with electronic stability control.

Are you suggesting, that car keeps applying regen even after wheels start to slip?

 

[jerry33]

I find it hard to believe, that Tesla wouldn't have fine tuned regen to work with electronic stability control.

It does, but on glare ice there is only so much traction available. Without stability control Tinm would have in the ditch. I've been able to get cars with traction control sideways on ice with no problem--just takes a bit of speed.

 

[AWDtsla]

It does, but on glare ice there is only so much traction available. Without stability control Tinm would have in the ditch. I've been able to get cars with traction control sideways on ice with no problem--just takes a bit of speed.

I've gotten it sideways in the rain. You exceed the limits of physics, there's only so much the electronics can do.

 

[Tedkidd]

Also, it would be really nice if Tesla offered an option to select regen braking level with paddle "shifters" or multiple "D" positions on the shift lever. On my Volt I really like being to quickly apply or disable lift throttle regen by shifting between "D" and "L"

GSP

+1

Great argument for regeneration paddles. Quickly turning regeneration up or down is a really nice feature. Drive the Mercedes and you'll wonder why Tesla doesn't have 'em.

 

[Lesifass]

Quickly turning regeneration up or down is a really nice feature. Drive the Mercedes and you'll wonder why Tesla doesn't have 'em.

Can't you do the same using your right foot (i.e. accelerator pedal) in a Tesla? It turns regen up and down. I guess the difference is that there are discrete regen "steps/settings" in the Merecedes and a continuous range between high regen/low regen/no regen/low acceleration/high acceleration in the Tesla.

 

[Tedkidd]

Can't you do the same using your right foot (i.e. accelerator pedal) in a Tesla? It turns regen up and down. I guess the difference is that there are discrete regen "steps/settings" in the Merecedes and a continuous range between high regen/low regen/no regen/low acceleration/high acceleration in the Tesla.

When you suddenly hit snow you want low regen. When you are dancing on the head of a pin, adding more pins only makes bad outcomes more likely, as this thread seems to support.

People I know with Tesla's turn regeneration off in the winter for this same reason - it's created hazardous situations for them. But low regeneration is a bummer, one pedal driving is one of the nice dividends that come with EV driving. On the Mercedes (and VW) turning it up or down is simple and instantaneous. Wading through screens is not.

To each their own. I've always felt it was an obvious oversight. If they made it an option, it's one I'd select.

 

[kirkbauer]

We definitely need to be able to turn off regen for snow (and racing)... glad you are OK!

Good news is it is probably impossible to flip your MS in that situation. I have done plenty of unintentional donuts in my old Toyota Truck back in the day.

 

[Magus]

Zero issues with standard regen in icy or snow conditions on my D. Michelin X ICE3 tires for the season.

 

[mspohr]

Zero issues with standard regen in icy or snow conditions on my D. Michelin X ICE3 tires for the season.

My 85D has been perfect in ice and snow. No slip or slide ever. Always keep regen on.
The D is much better.