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Idea: Regen could not trigger the 3rd brake light ?

Discussion in 'Model 3' started by Carl, Jun 4, 2017.

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  1. Carl

    Carl Supporting Member

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    #1 Carl, Jun 4, 2017
    Last edited by a moderator: Jun 5, 2017
    Wouldn't it be an idea if for regenerative braking only the two "20th century" rear brake lights came on, and the third brake light in the rear window was only activated when you really used the brake pedal? Would make it easier to estimate the level of braking of the car in front of you.
     
  2. JeffK

    JeffK Well-Known Member

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    Depending on how strong the regen is in an EV letting off the accelerator brakes more than people typically brake on the freeway to simply slow down a little. Whether regen or physical brakes, there's not really a good way as a human to know exactly how quickly they are slowing down you have to gauge the distance between yourself and the car in front of you.

    It's probably best to do whatever is possible to alert the driver behind you that your vehicle is slowing down. I'd say all three brake lights would be best in both situations. Some cars even have a brake light blink in order to better grab another driver's attention.

    Personally, I want as little chance as possible for someone to hit my future Model 3.
     
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  3. Carl

    Carl Supporting Member

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    :). But we did survive the 20th century with only two brake lights (actually such a third brake light was even forbidden in many European countries until around 1990, if I remember well). So my idea was simply: (i) slow regen (same as braking on the motor by shifting down with a stick ICE): no brake lights; (ii) high regen: two brake lights; (iii) actually using the brake pedal: three brake lights.
     
  4. stopcrazypp

    stopcrazypp Well-Known Member

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    Are people expected to decode that? Currently the brake lights just tell the driver you are slowing down, but by how much is judged by the driver behind.

    The third brake light became mandatory for situations where the regular brake lights are obscured. I don't see them changing the law to allow it to not be activated.
     
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  5. BluestarE3

    BluestarE3 Active Member

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    That would be informative only if the driver behind you understood what is meant by the various brake light options in order to react accordingly. Maybe some time in the future when EVs are more pervasive and the concept of regenerative braking is more universally understood, a graduated brake lighting system would be effective if it's adopted by all manufacturers?
     
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  6. SageBrush

    SageBrush Active Member

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    I'm happy to leave that task to radar, rather than taking the time to figure out if the car braking is a new-fangled Tesla
     
  7. Carl

    Carl Supporting Member

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    #7 Carl, Jun 4, 2017
    Last edited by a moderator: Jun 5, 2017
    I would think brake lights legally only have to go on when you use the brake pedal, so probably nothing legally wrong with my idea. BTW people today also have to decode whether someone is decelerating on his motor (no brake lights whatsoever, with an ICE) or applying the brakes (all lights on). So my idea probably makes decoding easier, not harder. Anyway, just an intellectual exercise, nothing worth starting a heated discussion about on this forum :)
     
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  8. stopcrazypp

    stopcrazypp Well-Known Member

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    The current law doesn't require it for regen, but then the same same logic applies: the third brake light is there in case the lower lights are obscured. If it is a level of regen necessary to activate brake lights, then the third brake light logically should be activated too, in case the lower lights are obscured.

    I'm not seeing why there needs to be a separate code for regen. Regen doesn't necessarily mean that the car is slowing down less than braking.

    Now on the other hand, the idea that there are progressive brake lights depending on the amount of deceleration might be useful, but that should happen regardless of it is regen or not.
     
  9. Carl

    Carl Supporting Member

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    True. But when you're using the brakes in a Tesla you're also applying regen (i.e. decelerating more than on regen alone) so I think we're saying the same thing.
     
  10. TEG

    TEG TMC Moderator

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    Some other ideas... Not that I am suggesting that anyone do them, but:
    #1: Level of regen could alter the brightness or number of lit segments so people know how quickly you are slowing.
    #2: level of brake pedal push could similarly be reflected in rear brightness levels.
    It seems brake light systems are all "binary" with on/off, not amount of braking force.

    In this other thread:
    Yellow/amber rear turn indicators?
    I mentioned that it can be hard to tell the difference between hazard lights active, and intermittent braking.
    If regen braking didn't activate the CHMSEL (3rd brake light) it would look even more like hazard lights were coming on.
    (Since both braking and hazard mode appears to use the same 2 red LED segments on model 3)
     
  11. stopcrazypp

    stopcrazypp Well-Known Member

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    Not really, what I am saying applies in general to all cars. What you are saying applies only to a Tesla (and only if regen is available: if the car battery is too full or it is too cold, then there may be a situation where stepping on the brakes is less deceleration than regen alone). I just don't think it is reasonable to expect people to decode this (given the brake lights are for other drivers to see, not for Tesla owners only).

    Something much more intuitive would need to be used, esp. as @TEG points out the current design already makes it too easy to mistake braking and hazard activation (with third brake light being the most obvious difference). Something like progressive brightness vs deceleration might make some sense.
     
  12. Jason S

    Jason S Model S Sig Perf (P85)

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    Actually that's where you are wrong. For a Tesla, the brakes are in addition to the regen braking, the regen is only associated with braking in that you can't use both pedals at the same time. The regen braking is significant.
    The brake lights go on when the deceleration is above a certain g-force, the lights don't go on when regen is happening and the car isn't decelerating (such as on hills or with light deceleration).
     
  13. mspohr

    mspohr Active Member

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    I think the reason for the third brake light up high, in addition to cases where the two side lights might be obscured, is that it is more in the line of sight for drivers behind and it more noticeable.
    I personally am happy to have all of the lights go on. If I am slowing down (even a little bit), I want everyone behind me to be alerted. Don't want some texting bozo to run into me.
     
  14. Carl

    Carl Supporting Member

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    Of course the regen braking is sometimes significant, and indeed sometimes significant enough to justify brake lights. When you are in addition using your Tesla's brakes, you are by hypothesis 'braking' (not necessarily decelerating) even more.

    I'm not sure deceleration as such enters into the equation, currently with Tesla. Been to the Alps in my Tesla a dozen of times and I have the impression that, going downhill, brake lights kick in when regen hits a certain level (independently of even whether you are really decelerating, just as with an ICE car, actually). Probably a good thing, because that's what everyone is used to (ICE cars will behave the same way).

    My one and only point was: why not have three levels of braking visible to the car behind you, in stead of just "no brake lights" vs. "all brake lights".

    @TEG adds an interesting idea I had not thought of: that third brake light is today generally a series of twenty-something LEDs in the rear window, so it could probably quite precisely indicate the level of braking one is applying (including going berserk when one slams the brakes).
     
  15. JeffK

    JeffK Well-Known Member

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    #15 JeffK, Jun 4, 2017
    Last edited: Jun 4, 2017
    In 1985, it was said that the third brake light would avoid 900,000 accidents on the road.

    Personally I'd be happy if the majority of the cars on the road actually had working brake lights (third brake light or otherwise)

    I like the idea of the brake light going berserk and telling all drivers nearby that I'm slowing down. Likewise, if I'm not in a car with AEB, I want to know when a car in front of me is slowing down. I want those lights to be as bright and noticeable as possible. It doesn't matter if they are slowing down a little or a lot. The driver behind needs to know.

    Making one light not turn on, or even turn on dimmer, is a good way to cause more accidents. In a normal car if you see brake lights, it's wise to cover the brake.

    We shouldn't go back to the 20th century, it was the dark ages, you were lucky to have airbags and a seat belt.
     
  16. stopcrazypp

    stopcrazypp Well-Known Member

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    There's a difference between 3 levels of braking and 2 levels of braking with 1 level tied to regen. Again, braking even in a Tesla does not necessarily mean more stopping force than regen (consider the situation where regen is not available and the brakes are applied).
     
  17. gregd

    gregd Active Member

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    Years ago (before the 3rd brake light was a thing) there was an experiment in San Francisco where the taxi fleet was outfitted with a strobe light on the rear trunk lid (I think). The harder the braking, the faster it flashed. From what I recall, it was very effective in cutting down on rear-end collisions. Why the final solution was a static 3rd lamp, I don't know, but suspect it was for simplicity and cost.

    The arrangement of the 3rd lamp above and between the two legacy brake lights was intended to evoke the triangle "danger" symbol in one's mind. How effective it was in generating that mental picture, I do not know. I suspect simply any dedicated 3rd light would be as effective.

    I like the idea of having the Tesla 3rd light "bar" change length in response to braking force. Could just be a software change, if the individual LEDs (or some grouping of them ) could be addressed separately. The harder problem would likely be regulatory. Presumably, the minimum size / brightness would be met with the first group, but just the idea of modulating the 3rd light at all could trigger the bureaucratic immune system at the NTSB.
     
  18. hacer

    hacer Member

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    Just the points I was going to make. The conclusion of course is that Tesla already has it perfect with respect to regen and the brake lights so it would be a mistake to not do the same thing with the model 3.
     
  19. Comacho

    Comacho New Member

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    You mean like this?
     
  20. TEG

    TEG TMC Moderator

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    Yeah! Nice find. Here is the text from that Youtube:
    I didn't even know they had that system. It just seemed like a logical idea to consider.
     

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