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Deceleration on Turn-in

Discussion in 'Model S: Driving Dynamics' started by ToddRLockwood, May 17, 2013.

  1. ToddRLockwood

    ToddRLockwood Active Member

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    I am both pleased and curious about the deceleration that occurs when making low speed turns in the Model S. When I approach the turn to my street, I'm going about 40mph down a 3% grade. In any ordinary car, I'd have to do some braking to make the turn. Regen reduces the speed to about 25mph, but then there is substantially more deceleration on turn-in. Could the steering angle be triggering additional regen? Sure feels like it. Or, perhaps it's just a result of the steering geometry. In any event, it's another wonderful feature of driving the Model S and further saves on braking.
     
  2. Doug_G

    Doug_G Lead Moderator

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    Turning will scrub off a little speed. Just the way tires work.
     
  3. mnx

    mnx 2013 P85

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    On a somewhat related note...

    When approaching a red light / stop sign on a hill it'd be nice to get more regen than what is currently available at low speeds. I find I grossly midjudge available regen in these cases and end up having to use friction brakes.
     
  4. brianman

    brianman Burrito Founder

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    Yup, this has been discussed before. On flat ground the regen seems to tail off around 5mph. On a slight incline you can reach 1mph easily. Only on heavy inclines do I get 0mph reliably without friction brakes.
     
  5. mnx

    mnx 2013 P85

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    Not sure if we're talking about the same thing. When approaching a red light on a downhill I find the car doesn't slow nearly fast enough (even though it is not using anywhere close to full regen). I wonder if more regen power could be allowed when pointing downhill at medium->slow speeds? (ie. <40mph)
     
  6. ToddRLockwood

    ToddRLockwood Active Member

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    I've never seen it as dramatic as on the Model S. It really feels like the rear brakes are being applied mid-turn. My other recent cars at this level would be an Audi S6 and a Ferrari 456GT. Neither of them felt like this. I wonder whether Tesla is actually doing something deliberate here to help keep the tail end planted during cornering.
     
  7. Doug_G

    Doug_G Lead Moderator

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    I dunno, I tend to take corners the way I was trained to do for the track. The physics is exactly the same on the street, so it's good practice:

    Brake in a straight line, turn in and maintain balanced throttle past the apex, then accelerate as you unwind the steering. So my foot is (lightly) on the throttle mid-turn. Where it's supposed to be!
     
  8. Raffy.Roma

    Raffy.Roma Active Member

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    @ToddRlockwood
    Maybe that the ESC on Model S is programmed in such a way to activate the brakes not only when the car doesn't follow the correct path but also when the centrifugal force overtakes a threshold.
    Or maybe that simply the ESC starts working and activate the brakes because it detects a very low deviation from the correct path. If this was the case it would mean that the ESC is so sensitive to detect deviations from the correct path that you don't manage to detect.
     
  9. trils0n

    trils0n 2013 P85

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    This seems to be key to me. Keep throttle applied mid-turn. If you back off the throttle, the regen kicks in (which is on the rear wheels) so that's probably why it feels like the rear brakes are coming on.
     
  10. JohnQ

    JohnQ Active Member

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    It's taking a lot of retraining for me to keep a neutral pedal through sharp turns (4 weeks with car). I use regen to slow for the turn but find I still have some when going into the turn ... hopefully I get that out of my system before the snow comes and things get interesting.
     
  11. mknox

    mknox Well-Known Member

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    Could be Tesla trying to balance maximum re-gen against not having your rear wheels break free in slippery conditions.
     
  12. wycolo

    wycolo Active Member

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    Since last firmware upgrade over a month ago, I've noticed a distinct two phase Regen which increases significantly somewhere around 10 mph. Then it totally craps out around 3 mph. So what TRL is experiencing might be this stronger regen just at the point he normally makes his turn. So it has little to do with turning and mostly to do with entering Regen Phase Two.

    1.1942 firmware on no-tech non-perf 85. I love this version and this is just one reason why.
    --
     
  13. brianman

    brianman Burrito Founder

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    We might be, not sure. My overall point was that there is clearly an "artificial" regen limitation that has little to do with how much the battery can safely absorb.
     
  14. ToddRLockwood

    ToddRLockwood Active Member

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    #14 ToddRLockwood, May 20, 2013
    Last edited: May 20, 2013
    That's the sort of thing I was imagining, but rather than applying brakes it might be applying more regen.

    - - - Updated - - -

    UPDATED

    The effect is felt just after turn-in, with no throttle. If you allow regen to slow the car from 40 to 25 (right foot completely off the accelerator) and take a turn, about midway into the turn you will suddenly feel a good deal more deceleration — as if something kicked the regen up to a higher level — although I'm not seeing a regen increase on the power meter.
     
  15. bhzmark

    bhzmark Active Member

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    Does anyone have any more info on the regen limitation? When is max regen (what the battery can receive) not available with full release of accel?
     

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