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Is Auto-pilot harsh on brakes?

Discussion in 'Model S: Driving Dynamics' started by Jlwine, Aug 7, 2016.

  1. Jlwine

    Jlwine Member

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    Let me give the seemingly necessary preamble, that yes, I did search and did not find this exact thing discussed--though I'm confident someone will correct me.

    When slowing or stopping for traffic, AP waits longer to start braking than I would and then slows down more suddenly. Assuming others have similar experiences. My question if anyone knows, by waiting longer it is AP using regen less and the brakes more heavingly than perhaps ideal?
     
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  2. Ciaopec

    Ciaopec Member

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    Perhaps I have a faulty understand of what I read in the manual. Starting on page 68 it says TACC will turn on the brake lights when aggressively slowing but my understanding is, short of emergency braking, it is just using regen and no braking.
     
  3. chillaban

    chillaban Member

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    I think it's mostly OCD -- it does use brakes more than a hypermiling driver but the few seconds' worth of regen is not going to make a huge impact on your overall efficiency or brake longevity.

    I think the way AP does it is fine, even if it doesn't match what a human would want to do.
     
  4. richardw0000

    richardw0000 Member

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    I'm inclined to think that Autopilot and TACC use the friction brakes more than necessary. I've developed way more brake dust on this car's wheels than I ever did on my Volt. I can even hear the brake pedal move when it is applying the brakes.
     
  5. WannabeOwner

    WannabeOwner Member

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    IF it IS all regen, is that more effective / efficient if done harshly, rather than gently? perhaps there is some "effort" that has to be overcome, in recharging the battery, such that higher kW, for shorter duration, is better?

    Not something I know anything whatsoever about!! but I'm curious to find out.
     
  6. Jlwine

    Jlwine Member

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    You stated my question much better than I did. That's exactly what I am wondering. Is it waiting longer because that creates more regentative power, or is it just a limitation of the technology at this point and it using more friction braking.
     
  7. Stiction

    Stiction Member

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    Given a specific delta V you need to lose by regen braking, the most energy will be gained by doing it at a constant minimal rate.
    In either acceleration or deceleration induction motors are more lossy the more put-in or take-out.

    So waiting in hitting it harder is not the best. The TACC does what it does because of other considerations...
     
  8. RedP85+

    RedP85+ Member

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    I tried a P90D for several hours and was in stop and go traffic. I definitely think that the AP used the brakes a lot more than I do when I drive my non AP P85+ in traffic. I love how little I use the brakes in my non AP Model S even in stop and go traffic.
     
  9. sloopee

    sloopee Member

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    Yes, i agree. The brake pedal would move so the car is definitely using the brakes! Just doesn't feel like "efficient driving" to me which can be a bit irritating!
     
  10. DillyBop

    DillyBop Member

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    no. they are electromechanical brakes. they can operate independently of the brake pedal.
     
  11. sloopee

    sloopee Member

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    but if the brake pedals move then the callipers must be clamping
     
  12. ShockOnT

    ShockOnT Quickish

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    Don't forget that some people actually have brake problems due to underuse, thanks to regen braking.

    Some occasional strong braking will keep the rotors rust-free.
     
  13. Fiddler

    Fiddler Member

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    I agree, bit it's not rusty rotors that's the big problem. The "frozen" calibers (from lack of use as you say) is the real problem.
     
  14. Baja30

    Baja30 Member

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    AP deffinetly is hard on the brake pads. Yes, the brake pedal moves when AP applies the brakes, it's how I figured out it wsa the actual brakes being applied. I agree, a softer approach to slowing down would be appreciated.
     
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  15. RedP85+

    RedP85+ Member

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    This is especially true in places with snow, ice and salt. I consciously use my brakes firmly at least once every time I drive.
     
  16. ShockOnT

    ShockOnT Quickish

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    Very true. Typing on phone or would have elaborated :)
     
  17. rxlawdude

    rxlawdude Member

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    2 rotor replacements in my 70D say yes to the title question.
     
  18. ShockOnT

    ShockOnT Quickish

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    Was it due to wear-and-tear, or some fault? Normally brake pads take the brunt of the punishment. The rotors usually survive many sets of pads.
     
  19. scottf200

    scottf200 Active Member

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    This is definitely my experience as well. The passengers even notice it. Please write Tesla <[email protected]> i.e. Subject: Feature Request - AutoPilot braking is harsh and slow to react until it gets close

    A feature like 'standard' or 'moderate' Auto-Pilot braking similar to 'standard' or 'low' regen would be great.
     
  20. Caligula

    Caligula Member

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    Ive played with this extensively during my commutes. I find that the AP does indeed utilize the brakes more than regen in some situations. My theory is that the car cant see as far ahead as I can (and/or make out the traffic at that resolution) and as such, it needs to react with more abrupt stopping force to meet the deceleration delta between you and the car in front. Part of this is based on my playing around with the follow distance selection, as setting it to 7 definitely helps reduce braking and increase regen use over lower (closer) settings.
     
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