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When, specifically, are hills held when hill holder is ON?

Discussion in 'Model S: Driving Dynamics' started by scottm, Feb 6, 2015.

  1. scottm

    scottm Active Member

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    I guess hill hold brakes came along since 6.1. I have MS Classic (Sept.14) with no auto-pilot gear.

    I have it turned on. And I've witnessed it working, so I've seen it do its job.

    Yet, in similar stopped situations, I've also witnessed no holding after taking my foot off the brake.
    The car will roll forward or reverse as soon as brake pedal lifted.
    It's been like this ever since I've had the car... and same through every software release since.

    Not sure if this is by design or something else?

    Are there a specific set of criteria under certain conditions that must be met for a hill hold happen?
    I've tried experimentation looking for a repeatable and predictable case:
    Degree of slope. How hard I press on the pedal at the stop sign, before release.
    When I apply brake (late or early) in the slope of regen doing most of the work.
    How hard or fast I initiate braking after getting off the accel pedal.
    Putting the brakes on only after regen has practically stopped the car.
    Repeated application of brakes at the stop sign.
    The amount of time at rest with pedal pressed.
    blah blah blah

    Can't find a pattern.

    Are there situations where we can expect hill hold not to happen (by design), even when switched ON?

    Not that this matters hugely... it's just nice to know if we have a "sometimes" feature, when turned on.
    I'd expect an ON feature to always be the same and react the same... right now it seems the car is just moody.

    FYI, I have Creep OFF, always keep it off.
     
  2. mibaro2

    mibaro2 Member

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    I have noticed a similar pattern. However, I think how long the brake is pressed for has something to do with it. In my own experiments, how forceful the brake is pressed seems to also play a part in it.
    I think it works about 80% of the time when I am on an offramp at the lights at the top of the slope.
    (I also have creep off).
     
  3. scottm

    scottm Active Member

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    I wonder if slope degree is the major factor?

    At a given stop, I've been able to repeatedly press brake, release, it holds then lets go, press brake again, release, it holds then lets go, .... many times in a row. With varying pressures, time waited between releases.

    My wife gives me these what the heck are you doing looks when I do experiments like this. Usually followed by "don't! it makes me car sick".
     
  4. mibaro2

    mibaro2 Member

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    It would make sense if slope degree was the major factor.
    Nothing like scientific tests to determine if it is the factor.
    (I'll drive up the foot of the escarpment stopping every hundred feet to see when it starts to hold).
     
  5. mknox

    mknox Well-Known Member

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    For me, it's hit and miss. My driveway has a barely perceptible slope, and Hill Hold almost always works there, yet I've been at intersections with much greater slopes and have had it not work.

    I've found that if the car rolls back and I "jab" the brake jerking the car to a stop, the Hill Hold will engage. If I gently apply the brakes at the same spot, it will not engage.
     
  6. AmpedRealtor

    AmpedRealtor Active Member

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    Tesla's hill assist should extend to all situations when the car is stopped, even on flat terrain. The "hill assist" should hold the car indefinitely until you press on the accelerator pedal. This way it will always work.
     
  7. mibaro2

    mibaro2 Member

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    Yes, that is the way I thought it would be when it was announced. However, it is not like that (at least not for me and 2 others so far).
    Is there any one that has Hill Assist working all the time like AmpedRealtor described?
     
  8. ItsNotAboutTheMoney

    ItsNotAboutTheMoney Active Member

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    Has anyone looked at the manual to see if it explains how to activate the hill assist? In my Prius it activates only with a fairly hard press of the brake.

    So release notes said:
    "When Model S is on a hill,Hill Start Assist will automatically hold the car for one second when the brake pedal is released."

    So I guess the inconsistency is when Model S detects a hill?
     
  9. trils0n

    trils0n 2013 P85

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    Is hill assist now a toggleable option? When it was introduced in 5.x? it was always on. Based on angle of incline. Subtle hills don't seem to trigger it. Holds for 1 second after releasing brake.

    EDIT: I see ItsNotAboutTheMoney beat me to it.
     
  10. ItsNotAboutTheMoney

    ItsNotAboutTheMoney Active Member

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    Except that that way you'd have less control over a maneuver on a hill. Personally, I think that the 1 second delay is a bit short. I think the Prius does 2 seconds.
     
  11. mibaro2

    mibaro2 Member

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    I think that is the problem...what defines a hill?
     
  12. UberEV1

    UberEV1 Member

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    The 1 second hold that Hill Assist provides should be enough to avoid excessive slipping of the clutch or stalling . . .
    (sorry, couldn't resist :biggrin: )
     
  13. invisik

    invisik Member

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    That's been my experience as well. Works great!

    -m
     
  14. AmpedRealtor

    AmpedRealtor Active Member

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    Just to be clear, I was saying it should be this way. It isn't this way currently.
     
  15. Franko30

    Franko30 Member

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    Hi,

    It always works for me in my Model S Signature (Germany, 09/2013) ever since Tesla introduced it way before 6.1

    Sent from my phone using Forum Fiend.
     
  16. AmpedRealtor

    AmpedRealtor Active Member

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    How so? In order for this assist to work, you have to use your brake and be at a complete stop. You are not doing any maneuvering when you are stopped, and to go forward you have to press the pedal in all circumstances anyway. Hill assist is transparent to the driver and should have no impact on maneuverability as far as I can tell.
     
  17. Franko30

    Franko30 Member

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    Cannot edit posts, therefore an UPDATE:

    Hill assist works on every terrain, all the time, but just for 1-2 seconds, not indefinitely.

    Cheers

    Frank

    Sent from my phone using Forum Fiend.
     
  18. scottm

    scottm Active Member

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    Well, a few of us are here to say, no, it doesn't work on every terrain. We have each found examples where she no work.

    And I am wondering under what conditions it decides (or forgets to decide) that it is to work.


    ...p.s. you can edit posts but maybe you have to be a member for so long or have some number of posts under your belt in order to do so.

    - - - Updated - - -

    I should clarify, there is no ON switch for the feature it is just on all the time, is my understanding.

    I think the feature was announced to me when the car upgraded to 6.1 which was the second day of ownership.

    Not sure if it was a selectable feature before that on earlier software versions.

    - - - Updated - - -

    I guess what I am asking for is for somebody find a spot where hill hold works sometimes, and sometimes not, and they can figure out what driving dynamic it takes to induce it to happen.
     
  19. jerry33

    jerry33 S85 - VIN:P05130 - 3/2/13

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    As far as I can tell, it's just the grade of the road coupled with the rolling resistance of the road for a given set of tires. If the grade is steep enough it works every time; if it's not, it doesn't. I assume this would be more of a problem if creep mode was turned on, but I've never tested. I suppose there is a "perfect" grade that could sometimes work and sometimes not depending upon the exact placement of the tires relative to the stop line and lane centre.
     
  20. Zarwin

    Zarwin Member

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    It seems to differ from car to car. I had a loaner and one of the things I noticed was hill hold engaging on much lighter slopes compared to my car.
     

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