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Reduced regen with lateral g's

Discussion in 'Model 3: Driving Dynamics' started by AltLogic, May 16, 2018.

  1. AltLogic

    AltLogic Member

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    I drove my Model 3 down my local windy mountain road. My plan was to use regenerative braking entering the sweeping curves and regenerative and friction braking for the sharp turns. I noticed that when I turned the wheel the regenerative braking was reduced. As soon as I straightened the wheel the regenerative braking would resume at full regeneration. It was a little surprising the first time it happened. I have driven my Model 3 up the same road a couple of times and it was a blast. I haven't seen anyone else report this behavior. Fortunately, the increase and decrease in regeneration was smooth.

    Also, it appears the programers are a little overprotective with cruise control too. When I am enter the freeway onramp at the speed limit followed by increasing the set speed for cruise control the car will not accelerate till I am going almost straight.
     
  2. animorph

    animorph Active Member

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    Not something I've seen with the X. It is possible that changes in your speed caused the differences in regen, it does vary with speed as you slow down during a normal straight-line stop.

    Was that basic "cruise control" or Autopilot traffic aware cruise control (TACC)?
     
  3. AltLogic

    AltLogic Member

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    My Model 3 doesn’t have EAP/TACC/Autopilot.

    It was very obvious on corner exit. While in the turn there was very little if any deceleration. As soon as the steering wheel was close to straight there was an increase in deceleration. It was like: this is cool I am driving 45 mph around this downhill sweeper and everything is steady state fun, straighten up the steering wheel and now I am slowing down when I want to maintain speed. Next curve comes up and I want to enter it at 35 while letting the regen trail brake for me, as I enter the regen goes away and I have to press the brake pedal lightly on corner entry, coast without regen to mid corner and hopefully remember to ease on the accelerator to continue “coasting” when I straighten out.

    This is well below the limit driving on a fun road. If I was on a track I wouldn’t notice it since I would enter the turn with the friction brakes and exit with lots of accelerator pedal application.
     
  4. swaltner

    swaltner Active Member

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    I’d repeat the setup and have a passenger along keeping an eye on the power meter shown below the speedometer on the center display. This would tell you for certain that it’s adjusting the amount (kW) of regen and not something else coming into play. I’m not doubting you, just sounds like an odd correlation to have.

    Maybe traction control is coming into play and trying to limit the braking to keep from entering a skid. Just spitballing at the underlying reason...
     
  5. goto10

    goto10 Member

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    I haven't noticed regen strength to be dependent on steering wheel position.

    I've found that the "strength" of the regen varies with speed. If I'm going 80 and lift off the accelerator I feel relatively little slowing. If I'm going 40 and do the same thing the effect is much stronger. It it possible that you are noticing these speed-related differences in regen coincidentally with how you are entering and exiting turns, which will tend to occur at different speeds? Perhaps you were entering the sweet spot for regen when you were exiting turns and straightening the wheels?
     
  6. DR61

    DR61 Member

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    I would expect this behavior. As far as I know, there is no system to detect frictional coefficient of the road surface & tire patch, so it is prudent to reduce load from regeneration on the drive wheels when turning with moderate lateral g forces.
     
  7. Skidmark

    Skidmark Member

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    Mine does it too, but I have not seen it happen on an S/X. Going around a reasonably hard corner, regen pretty much turns itself off until the steering angle is reduced to a certain point. It is a bit disconcerting if you're not expecting it.
     
    • Informative x 1
  8. bxr140

    bxr140 Active Member

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    Same thing happens on RWD S’es too. Having all your braking at the rear of the car with high lateral load is a recipie for disaster. By turning off regen you’re forced to use the actual brakes, which more proportionally loads the car.

    You shouldn’t be braking that deep into a corner anyway. ;)

    ***I live at the top of a hill.
     
    • Informative x 2
  9. favo

    favo P3D+ owner

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    Presumably dual motor/perfomance versions keep more regen in the corners.
     
  10. bxr140

    bxr140 Active Member

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    Yes. That’s the way the S/X models work.
     
  11. evJOULE

    evJOULE Member

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    I wonder if it isn't more of a safety feature. Like Dr61 said, having full region kick-in while entering a corner on slippery surfaces (rain, snow, ice) could cause unexpected changes in the cars behaviour.
     
    • Helpful x 1
  12. Skidmark

    Skidmark Member

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    Yes, it's definitely put in there to reduce the opportunity of rear-wheel traction loss leading to a spin, but on the other hand, it also introduces a behavior of the car that could be very unexpected to a driver. The current behavior is probably the lesser of two evils.
     

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