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Regen and Brake Lights - Highway Issue

Discussion in 'Model S: Driving Dynamics' started by Zas, Aug 21, 2013.

  1. Zas

    Zas Sig. Performance #2113

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    When driving on a highway, and letting go of the accelerator, the regen kicks in and then automatically lights up the brake lights, even though the driver did not press on the brake pedal. I do understand the regen brake light comes on only after a certain rate of deceleration has occurred, but nevertheless, this would cause a chain affect to the drivers behind you... as they would think you would be braking.

    The Edmunds article below mentions the same issue, ..

    http://www.edmunds.com/tesla/model-s/2013/long-term-road-test/2013-tesla-model-s-regenerative-braking.html


    ...I think Tesla would be wise to reduce the number of lights that come on during 'regen braking' ( maybe just a few lights light up ) see below example of regen brake lights vs. brake pedal brake lights.

    .. or maybe even a different color like orange ?

    Capture.JPG


    Capture1.JPG
     
  2. vfx

    vfx Well-Known Member

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    Agreed and both ideas suggested 6 years ago on the Roadster.
     
  3. steve841

    steve841 Active Member

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    You get very good at modulating the throttle without activating the brake lights .....

    But nonetheless, here in FLA ... you don't need regen to see half the people's brake lights on for no reason or turn signals (with no intent to turn) for that matter ....
     
  4. NigelM

    NigelM Recovering Member

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    I disagree. Regen causes Model S to slow much faster than an ICE that is coasting and on the freeway cars tend to be much closer together than is recommended. When someone is driving behind me at speed I want him/her to know that I'm slowing down. Half lights coming on tells the driver behind that something is happening, but he/she is unlikely to go "Oh, that must be a Tesla and that's his regen braking, so he's going to speed up again......or maybe not?"

    Orange lights are turn/hazard warnings and trying to educate the entire car driving population that they're anything else is a lost cause.
     
  5. vfx

    vfx Well-Known Member

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    I disagree with you.
     
  6. Todd Burch

    Todd Burch Electron Pilot

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    Most people on the highway aren't going to notice a difference between "full" brake lights and "partial" brake lights. They'll see brake lights as brake lights, and will cause people on the highway to brake either way.

    The way I see it, you're slowing down just as fast as an ICE would be slowing down while applying their brakes, so the lights should come on.

    I think you just need to adjust how you drive (use cruise control and apply pressure to the pedal before releasing cruise control) so that your brake lights don't come on. It's not that hard--just takes a little bit of adjustment.

    My two cents.

    - - - Updated - - -

    As for using other colors, there are laws against that.
     
  7. gnelson

    gnelson Member

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    I agree with you!
     
  8. dpodoll

    dpodoll Member

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    I agree
     
  9. strider

    strider Active Member

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    Some vehicles automatically blink their hazard lights if you really jam on the brakes but I haven't looked into whether this helps avoid accidents or not.

    I think that brake lights should vary in intensity (not location) based on how quickly the vehicle is slowing. But this would need to be a nationwide mandate like the CHMSL's so everyone would be trained on it and it would become common. Tesla cannot do this on their own.

    For the OP, just be smooth with the accelerator pedal and let the car work as designed. I've been driving my Roadster for 3 years and have never noticed any untoward behavior based on brake light usage.
     
  10. JohnQ

    JohnQ Active Member

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    Both types of cars are on the road today. Manual transmissions that can have aggressive deceleration without brake lights and automatic transmission where greater deceleration than air and rolling resistance (and a touch of engine braking) results in brake lights coming on. I don't see how changing the behavior of the brake lights on the MS would result in any changed behavior by other drivers. If I need to decelerate aggressively, I have heavy regen, and brake lights come on. If I need to decelerate more slowly, I have light or no regen and the brake lights don't come one. Seems like ideal behavior to me.

    Finally, in an ICE, when I see brake lights, I don't automatically hit my brakes, I cover my brake so I can react depending on what my depth perception tells me is happening. In the MS, I simply ease up on the accelerator pedal to a neutral position until I figure out the same thing.
     
  11. Gee-Man

    Gee-Man Member

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    I disagree with the OP as well. I like how the MS behaves right now. If my car is physically slowing down, I don't think the drivers behind me need to know or care *why* I'm slowing down, regardless of whether it's because of heavy regen or me hitting my brakes. The brake lights lighting up at a certain level of deceleration communicates the clearest message to other drivers: "This car is slowing down, so you'd better be prepared to slow down or stop too."

    As someone else pointed out, I think a more aggressive brake light pattern when rapid deceleration is detected might be an interesting idea (rapid flashing of the brake lights, perhaps?). But that has nothing to do with the Model S, it's just something that would be useful in any car if somebody slams on the brakes.
     
  12. markb1

    markb1 Active Member

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    I was behind a Model S driving down a hill the other day, and its brake lights kept going on and off, even though traffic was moving at a steady speed. I used the info screen to see if my car was doing the same, but it was not. I guess it was just one of those people that treats the accelerator as a binary input.
     
  13. kendallpb

    kendallpb Model S: P 8061

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    But effectively, you are, whether the result is due to pressing on something named a "brake" or releasing something named an "accelerator"...whether your battery charge is increasing or not...the car is slowing down as if you were in an ICE, pressing a brake. The why and how are irrelevant; you're slowing down enough that drivers behind you should see a clear indication consistent with what happens when they slow down--not odd lights or intensities. So, sorry, I disagree. Tesla's tuned this well, methinks. Whether someone brakes because they see your lights--that's a different issue (people sometimes overreact to any slight touch to a brake in ICE cars, too, without necessarily noticing that the car isn't really slowing much or at all--though some would say, better safe than sorry).

    - - - Updated - - -

    P.S. I think the Edmund's blogger doesn't understand how it works, and a rheostat is a bad idea; you control regen by how much you lift your foot off. It sounds like his wife just took her foot off the brake maybe? Anyway, it doesn't sound like they understood and did a good test; it's gradual as you release the accelerator and the lights don't go on the instant you start.
     
  14. dsm363

    dsm363 Roadster + Sig Model S

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    It just takes a little time to get used to driving the Model S and some may get there faster than others. If you fully or almost fully lift off the accelerator at highway speeds then yes, you will see the lights come on but with normal pedal variation you don't.
     
  15. Effects

    Effects Member

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    I'm sure a group of Lawyers had something to do with this system.
     
  16. LJordan

    LJordan Member

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    BMW has a system they call Adaptive Brake Lights:

    Adaptive Brake LightsBumper-to-bumper collisions most often occur when the driver behind you didn't realize how hard you were braking. Our Adaptive Brake Lights help eliminate that scenario by emitting a larger, brighter light the more force you use. It allows those behind you to clearly see whether you're lightly tapping the brakes to slow down or applying full force for a sudden stop.
    http://www.bmwusa.com/Standard/Content/Innovations/Engineering/Safety.aspx
     
  17. Cattledog

    Cattledog Active Member

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    My recollectioin is the decelaration with the 30KW max regen in the 'Low' setting does not get activate the brake lights. I recall checking the screen (info?) where it shows what lights are on and it did not show illuminated brake lights on Low at highway speeds, it did on Standard.
     
  18. brianman

    brianman Burrito Founder

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    I think I disagree with both of you because you're both offering binary opinions: yes / no to enabling / disabling one set of lights for the regen-only braking case.

    I'd like to see Tesla use the whole bar as a deceleration strength indicator. When braking -- from whatever technology -- brighten or use more of the bar if it's a hard/high-decal. Some UI can be done really well with (simulated) analog.

    - - - Updated - - -

    Unless I'm misunderstanding you, I think they can. They can't play games with the lights on the sides but the bar in the middle they can do interesting things with.
     
  19. FlasherZ

    FlasherZ Sig Model S + Sig Model X + Model 3 Resv

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    It is variable, based upon your speed. At higher speeds, the cut-off seems to be 30 kW, and therefore "low" wouldn't activate the brake lights. As you reach slower speeds (e.g., 30 mph) and regen is reduced, the brake lights are still on, despite being only at 15 kW, etc. So it seems to be a rate of deceleration.

    The only concern I have for brake lights being on for regen is when I'm aggressively trying to slow down because I'm going past a duly authorized gum ball machine sitting in the middle of the freeway. I would like for the occupant of said machine not to get the wrong impression because of brake lights on my car, the result of people who insist on slamming on their brakes to drive 5 mph under the speed limit when passing the police car. If the officer sees my brake lights, he may assume I'm trying to slow down because I was speeding, which is never the case, when instead I was having to slow down to avoid hitting the inconsiderate, erm, driver, in front of me who decided to slam on his/her brakes.
     
  20. mknox

    mknox Well-Known Member

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    Really? It's kinda common practice in my parts to hit the 4-ways if you have to slam on the brakes in a sudden freeway slow-down. Could that be what you're seeing? I've never heard of it happening "automatically".
     

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