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Regenerative Braking

Discussion in 'Model S: Driving Dynamics' started by jtran65, Jul 26, 2013.

  1. jtran65

    jtran65 Member

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    I am not sure if this has been discuss here : but when I allow the car to slow itself using regenerative braking, the brake lights comes on. Has anyone notice on their rear view camera the car behind changing to another lane because they seem to be annoy?
    Is there a way to slow down the car without having the brake lights turn on so often when you let off the pedal.
    Hopefully I will get this down to a science and mimic like an ice car when slowing down.
     
  2. ElSupreme

    ElSupreme Model S 03182

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    The brake lights go on with an accelerometer. So actual rapid deceleration. So you can regen and not have the brake lights kick on, but in general full regen kicks the brake lights on.

    If you want to have an idea when your brake lights go on you can press the Tesla 'T' on the top of the main display. It brings up the software version screen. When your brake lights go on the picture shows them also. You can see at slow speeds the brake lights can come on with 30kW of regen, where at interstate speeds even the full 60kW won't necessarily kick on the brake lights.
     
  3. capt601

    capt601 Vin02324

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    Don't let off the "go" pedal so hard. Drive with the "go" pedal and gradually slow down using it by gently releasing pressure. It is a technique and will not take you long to figure it out.
    Have a friend ride with you and push the large tesla T at top of screen, that way the passenger can watch when the brake light comes on. Try driving around and get the feel of the Go pedal and let them tell you when the brake light comes on the screen.
     
  4. jtran65

    jtran65 Member

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    Thank you for the reply
    I think its a matter of getting use to 1 foot pedal.
     
  5. Todd Burch

    Todd Burch Electron Pilot

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    Yes, it is. I have looked fairly closely at the brake light behavior with regen, and have to admit that Tesla has executed it nearly flawlessly--meaning that they go on when they should go on, and they don't when they shouldn't :).

    But yes, when driving without cruise control, you will soon get over the habit of rapidly removing your foot from the accelerator unless you want to start braking quickly. One foot driving really is excellent!
     
  6. kjl

    kjl Member

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    I definitely find that the brake light goes on much more than I wish it would. Maybe it's because I'm used to driving a stick, so I'm used to some slowdown when I let up off the accelerator. When I'm doing a lot of minor speed adjustments (i.e. in fast, but busy traffic), I think the brake light is probably blipping on and off enough to be annoying to the person behind me. It's hard to stop doing this, as I'm used to doing the same in a manual (downshifting, engine braking, etc.).
     
  7. jtran65

    jtran65 Member

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    I feel the same way! It makes me feel like the person behind me thinks that I can't drive a car. drives me crazy.
    I think eventually we will get this down correct by easing off the pedal .
     
  8. brianman

    brianman Burrito Founder

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    This might imply that cars behind you in your stick vehicle were probably often dismayed by your "surprise" deceleration. ;)
     
  9. Todd Burch

    Todd Burch Electron Pilot

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    If you're slowing down above some threshold of deceleration, the brake lights should come on, regardless of WHY you're slowing down. If you find you need to frequently adjust your acceleration enough to force the brake lights on, you're probably following too closely (just like 90% of the American driving public).
     
  10. strider

    strider Active Member

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    I agree. I've been driving a Roadster for almost 3 years and have never had a problem. If you're smooth and don't "jump" off and on the pedal it just works. Drive smoothly and be happy. Objects in mirror no longer matter :)
     
  11. kjl

    kjl Member

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    No, I don't think that's accurate. I just like to be "crisp" with my driving, if that makes sense. If there's a guy going 65 mph a 200 feet in front of me and I'm also going 65 mph, but I'd rather be 40 feet behind him instead of 200, I would rather not, say, speed up to 75, and then slowly feather my speed so that my speed slowly drifts 70, 69, 68, 67... and hits 65 precisely when I'm 40 feet behind him. I'd rather speed up to 75 until I'm 45-50 feet behind him and then quickly drop back down to 65 (obviously not by slamming on the brakes, but I'd just rather that the deceleration happen crisper and faster, but that the brake lights didn't blink on).

    This seems to be worse on a downhill, where even a moderate 15 or 20 kW regen is not enough to slow down the car, and certainly not enough to slow down fast enough to make it easy to slide in and match speeds behind somebody at a given distance.

    For example: I get into the fast lane to pass somebody, and accelerate so I'm not hogging the fast lane too long. You know what I mean: the guy in the middle lane is going 74 and I want to go 75, so I pass him on the left, but temporarily boost up to 80 so I'm not being a pest taking 45 seconds to pass one car. Then I get back in the middle lane and want to drop down to 75 again, but I don't want to scare the guy I just passed with a brake light - I'm just slowing down to a speed that's still faster than he's driving, but maybe I want to do it quickly, so I don't rear end the guy in front of me.
     
  12. sp4rk

    sp4rk Banned

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    I'd rather speed up to 75 until I'm 45-50 feet behind him ...

    That's tailgating. Unless you're Leilani Munter. :)
     
  13. dsm363

    dsm363 Roadster + Sig Model S

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    Yeah. That is tailgating. You actually want your brake lights on when the decelerate quickly so people tailgating you have more warning.
     
  14. Todd Burch

    Todd Burch Electron Pilot

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    Give it some time and practice. You'll find you can brake fairly strongly without the brake lights coming on. As others have said, it's not based on kWh...it's based on deceleration, so at higher speeds you can have stronger regen without brake light triggering than at lower speeds.
     
  15. kjl

    kjl Member

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    Well, I have no way of proving it, but you'll just have to take my word for it that I'm not the fast, aggressive, tailgating idiot I was in my 20's anymore :). I'm not sure exactly what the measurement "45-50 feet behind" somebody actually looks like. These days I definitely feel like my speed is about par with the rest of traffic (usually cruise is at 70-75 and I am probably in the 75th percentile of other car speeds), and I don't feel like I drive inconsiderately or recklessly. Actually, even when I was in my 20's and thought driving was a game, I always had this rule where I considered it a failure if anybody ever had to step on their brakes because of my actions - I was trying to be like this silent, driving ninja that would try to get to my destination as fast as possible without anybody else having to modify their behavior because of me.

    Anyway, perhaps my example was not quite correct, but to cut to the chase, sometimes I simply want to be able to pick a spot and fall into that spot at a particular speed, and sometimes the deceleration required to hit that position and speed triggers my brake lights (prompting the guy behind me to think I'm an idiot), whereas in my old car, it would obviously not trigger my brake light (and the lack of brake lights for the given situation would be more useful information to drivers around me). Usually this involves me driving faster than I want to be driving in order to pass, and then wanting to fall back out of the left lane as fast as possible so as to clear the left lane for faster traffic, while neither tailgating/ramming the car in front of me or scaring the pants off the guy behind me.

    edit* - but I'm sure I'll get used to it. It's just a new car with new dynamics. Probably won't even be conscious of it in a month.
     
  16. strider

    strider Active Member

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    My last car before my Roadster was a C6 Corvette w/ a manual xmission. It has a 6.2L V-8 so when downshifted slows as fast as pretty much any ICE. The Roadster (and your MS) at full regen slows much quicker than a downshifted ICE and people behind you should be notified.

    At the end of the day, my statement stands. If you do something abruptly (or crisply) the brake lights SHOULD illuminate to tell the people behind that you are maneuvering. As you get more used to the car you'll get smoother and the brake lights won't illuminate as often.

    As an aside, I've always been a fan of variable intensity brake lights based on deceleration. So a light decel results in dim brake lights and brighter and brighter and ultimately flashing in a "panic" stop. I think the krauts have experimented with this in a limited way.
     
  17. stsanford

    stsanford Member

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    You just described my driving philosophy. As a 911 driver who did exactly what you were mentioning... Looking for "slots" to file the car in during traffic, or higher congestion times, I get what you're describing... I'm finding that with some modification, I'm getting the same result without annoying the driving public around me. I'm also finding that I'm driving 5-10 MPH slower on average, and leaving a lot of room. To decelerate from 65 to 0 for a stoplight and have to use the brakes for anything but the last 3 MPH is now a FAIL in my book <G>
     
  18. Ziggy

    Ziggy Member

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    If you're interested in seeing when the brake lights turn on, touch the Tesla symbol on the center console and when you let of the accelerator the image of the car on the screen will depicte the brake lights. This will confirm whether the brake light is actually coming on or not when letting off the accelerator. Based on what you learn, you may need to provide more space between yourself and the car in front to avoid excessive brake lights.

    - - - Updated - - -

    Opps, just notice Elsupreme gave the similar advice.
     
  19. ElSupreme

    ElSupreme Model S 03182

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    I always thought about having the 3rd center mounted brake light light up in sections. Just the center section is light braking, as the braking gets harder the bar gets wider.

    The problem I keep getting hung up on is how do you enforce some sort of consistency across different vehicles, and brakes in various states of repair. I can see a slowing/stopping interstate having people show barely braking, while others seem maxed out.
     
  20. HHHH

    HHHH Member

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    There are some cars on the road now with a similar feature. What it does is flash the third brake light either under heavy pressure or flash when the person first steps on the brake, so the driver behind knows how long they've been on the brakes.
     

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