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How does regen braking work in slippery conditions?

Discussion in 'Model S: Driving Dynamics' started by Borgholio, Oct 11, 2016.

  1. Borgholio

    Borgholio Member

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    I currently drive a Prius, and naturally it uses blended braking, part regen / part traction. The "coasting" regen is very weak and doesn't slow the car down much at all. In slippery conditions, when you step on the brake, the regen braking stops and the ABS kicks in to make sure you can stop without skidding out of control.

    I am in the line to get a Model 3 next year, and I am curious how Teslas operate compared to my Prius. I know the coasting regen is much heavier than the Prius, able to almost stop the car completely. If I were to take my foot off the accelerator on a slippery surface, how would the Tesla handle it? Would it slip out of control due to the heavy regen braking, or does it have a sort of ABS that works when doing heavy regen? Or does it disable it completely and require you to use the brake pedal for actual ABS?

    Thanks!
     
  2. DaveVa

    DaveVa Sig Perf #236 VIN #484

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    I have a rear wheel drive "classic" Model-S. In the snow, I turn the down the regen. During the first winter (2012), we had major snows and the full regen was enough to make the rear wheels break traction.
     
  3. trils0n

    trils0n 2013 P85

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    Regen braking and ABS work together to ensure everything is safe. If you let off for full regen on a slippery surface, most likely nothing will happen, unless you are driving on snow with all seasons. The traction control on Tesla vehicles is excellent and works quicker than traditional ICE traction control. Under extreme circumstances, it will automatically reduce regen power to prevent slipping or spinning (I've only seen that once in over 3.5 years, and that was intentionally trying to test the limits by going too fast through standing water.) The traction control is top notch and the Model S is extremely easy to drive under nearly all circumstances.

    To me, regen seems to encourage driving smoothly, which seems to limit situations where you suddenly apply brakes or regen, which also helps with safety in slippery conditions.
     
  4. Borgholio

    Borgholio Member

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    What happened in that situation? Did the car try to regain traction or did it simply lose control?

    That sounds to be different than what DaveVa was describing. Could it be your car had upgraded software which did a better job of maintaining control?
     
  5. trils0n

    trils0n 2013 P85

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    Sounds like with both have cars of similar vintage. We are probably describing the same behavior. Regen power gets cut when slipping is detected. That means slipping occurred, and regen gets momentarily cut to stop the problem. Setting to low regen makes it easier for some people to avoid the slipping in the first place, before traction control activates. You can accomplish the same thing by not rapidly lifting off for max regen in slippery situations, just like you shouldn't slam on your conventional brakes during poor road conditions.
     
  6. Borgholio

    Borgholio Member

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    Gotcha, thanks! Looking forward to my new Tesla and trying to work out any potential learning curve issues well beforehand. :)
     

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