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regen and brake lights

Discussion in 'Model S' started by gvands, Mar 27, 2015.

  1. gvands

    gvands Member

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    I was wondering ff the brake lights are on, every time you slow down with regen?
    Is this in both regen settings? Can you disable this brake light reaction?
     
  2. CraigS

    CraigS Member

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    They turn on once you hit a certain level of regen...if you have just a tiny green bar, they're not on. You can test this yourself and get an idea when they turn on by driving down a darker street and using your backup camera - you can see the reflection on the street.
     
  3. trils0n

    trils0n 2013 P85

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    An algorithm determines when to turn them on that takes into account regen level, and data from an accelerometer.
     
  4. gvands

    gvands Member

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    Thanks, I'm eagerly awaiting my delivery in june/july. I noticed while driving my ice that I often slow down during driving by
    just taking my foot of the gas, but I was thinking it could bug people behind me when I'm in the Tesla, if they see the breaklights
    going off and on all the time..
     
  5. jerry33

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

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    That doesn't happen unless you have an on/off driving style. Whether the brake lights go on or not depends on the rate of deceleration. With the Model S you modulate the braking speed in the same way you modulate the acceleration speed. Note that the smoother your driving style is, the more range you will get and the less often the brake lights with turn on. Once you get the car you can watch the camera at night to see how they behave. Generally it's about the same as any other car.
     
  6. MassModel3

    MassModel3 Member

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    Yeah, people have posted that they've received nasty looks (and worse!) on the highway due to regen causing the break lights to go on and off frequently in certain traffic conditions.

    I think that if you don't follow too closely and don't dramatically lift your foot off the pedal when traffic slows up ahead, you don't tend to flash the guy behind you so much. The habits of driving an ICE can take a while to break yourself of as you learn to drive with heavy regen instead.
     
  7. caddieo

    caddieo Member

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    One way to familiarize yourself with how the brake lights behave in relation to deceleration is to drive down an empty street at night and play with the accelerator. Your rear view cam screen will show them flashing on and off. In an ICE, abrupt lift-off does not turn the brake lights on as there is no regenerative deceleration - you have to modulate deceleration (and thus turn the brake lights on and off) with the brake pedal. In a Tesla, modulation of right foot pressure on the accelerator is key instead of abrupt lift-off and determines whether or not the brake lights go on. For a lot of people, learning how to feather the pedal is a new learning experience and the night-time drive suggested is a good training aid.
     
  8. andrewket

    andrewket 2014 S P85DL, 2016 X P90DL (soon 100)

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    You can also see the brake lights on the "about" screen when you push the T at the top. The car displayed reflects the light status.
     
  9. Larry93428

    Larry93428 Member

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    It is time to quit calling these "brake lights". They are "deceleration lights" and indicate what the vehicle is doing, not what your foot is doing.
    Hah, as EVs become more common, the "others" will have to learn. Tough on them.
    ~Larry
     
  10. Andyw2100

    Andyw2100 Well-Known Member

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    I do sometimes worry that a driver behind me at a stop light or something may assume my disappearing brake lights mean I'm accelerating, and rear-end me. For example, if I'm slowing to a stop with regen, at some point the brake lights will go out, and I'll still be slowing. If a driver close behind me isn't paying attention, and assumes that means I'm now accelerating...
     
  11. LetsGoFast

    LetsGoFast Active Member

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    I can't even stop calling it the gas pedal.
     
  12. AoneOne

    AoneOne Member

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    Going down a steep hill, holding the speed constant with regen, I'm the only car without lit "brake" lights.

    However, if the hill were so steep that I had to use a bit of brake to keep my speed, I'm guessing that the "brake" lights would be on.

    Same net acceleration, different lights.
     
  13. Atebit

    Atebit Member

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    No such thing as deceleration. You'd have to call them "negative acceleration" lights.
     
  14. Chrisizzle

    Chrisizzle Member

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    If you put the battery charge screen on your main display, it shows a model of your car. The headlights, signal lights and brake lights on this model all work in real time. It shows whether your brake lights are in during deceleration.
     
  15. jerry33

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

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    ss
    From the brake pedal, the lights work just like any other car.
     
  16. ecarfan

    ecarfan Well-Known Member

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    Last year I did a test at night on a dark street so I could easily see when the brake lights came on in the rear view camera display. I consistently found that they came on only when I completely lifted off the "go" pedal but did not touch the brake pedal (of course the came on with the slightest bit of pressure on the brake pedal). As long as I maintained just a bit of pressure on the "go" pedal they did not come on.

    So yes if you are going down a hill and holding speed with just moderate pressure on the "go" pedal the brakes lights do not come on. I do not perceive that as a drawback. You are maintaining a constant speed.

     
  17. caddieo

    caddieo Member

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    Agreed. However, I prefer using the rear view screen at night as I do not have to take my eye off the road to look at a specific spot. The large red glow of the screen when the brake lights go on impacts my peripheral vision very nicely especially if the rear.view occupies the upper half of the screen.
     
  18. HebrHmr

    HebrHmr Member

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    I often engine brake on my motorcycles. When I start to slow down I just give my front brake a few taps to engage the brake light. It doesn't come back on until I brake the last 5-10 mph. I have never had or heard of anyone having an issue with it.
     
  19. Andyw2100

    Andyw2100 Well-Known Member

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    Glad to hear that. I've been a little worried about it.
     
  20. Larry93428

    Larry93428 Member

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    Just curious; when the trucks use the engine brake do the brake lights come on?
    They are slowing - generating noise, not electricity - but it is similar.
    ~Larry
     

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