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regenerative braking poll

Discussion in 'Model X' started by smocfi, May 3, 2017.

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Do you use Low or Standard regenerative braking?

  1. Low (mostly or always)

    3 vote(s)
    1.2%
  2. Standard (mostly or always)

    235 vote(s)
    97.1%
  3. Depends on driving conditions

    4 vote(s)
    1.7%
  1. smocfi

    smocfi Member

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    I'm curious if people prefer standard or low. I use low myself, standard seems like way too much braking.
     
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  2. Tam

    Tam Active Member

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    I prefer one pedal driving. More regen options such as "high", extra high, super high... will be appreciated.
     
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  3. FlyF4

    FlyF4 Member

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    Yup, my thinking as well. Unlike my wife who looks at the bumper in front of her and also keeps a lead foot until 20 feet before a stop sign, I look much further ahead, gauge the lights, traffic, etc. I get better mileage with low setting and she gets better mileage with higher setting. Preferably, I would like an even lower setting.
     
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  4. Saghost

    Saghost Active Member

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    How long have you been driving electric?

    Most of us rather quickly get used to one pedal driving - being able to drop a bunch of speed without having to reach for the brakes is very convenient on freeways and surface streets alike.

    Of course, then you get in another car or have a cold pack one morning and it feels very unnatural the way the car keeps flying forward... :)

    Keep in mind, anytime you hit the brake pedal in a Tesla, you're throwing away energy - energy that you could have kept if you had more regen enabled.
     
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  5. roblab

    roblab Active Member

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    Having driven Tesla for 4 1/2 years, RAV4EV for 6, a person gets used to regen and usually wants more. I was amazed at how many people do not understand that regen is variable with the accelerator pedal and would complain that it was "too strong", etc. Nowadays, Tesla has made the regen cut in so gently it's hardly noticeable, but still very nice. See the light change down the road, pull foot back, car slows gently, stronger, almost too much? Then push pedal. Oh, Look, it's not too strong!

    It seems to me, in my own experience of letting people drive, that some newbies think it should be like an automatic tranny, and should just coast. Others get it. Oh, it's like engine braking, only better!

    I use my brakes about the last 20 feet from the stop sign. Regen does the rest.

    Maybe they'll make a selector like the sound: "Goes to eleven!"
     
    • Like x 10
  6. FlyF4

    FlyF4 Member

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    Hmmm, well that hasn't been me. I will never get used to it. I guess it all depends on how one drives and how much they gauge what comes ahead. Then again, I've flown planes a lot more than I drove ;)
     
  7. evp

    evp Nerd

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    I think having "settings" is silly. There should be a slider giving infinite control between 0 and the maximum the hardware can support, modulo any safety considerations.

    One possible safety consideration: If the traction control ever kicks in during regen, I might be interested in the regen value being backed off to where it was needed to regain traction, and possibly creep back up to the manual setting after a while. This is based on my experience coming down steep snowy mountain roads in a classic 2WD. 4WD drivers might not need this. (Let the flaming commence!)
     
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  8. Lloyd

    Lloyd Well-Known Member

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    Low on ice only
     
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  9. Haxster

    Haxster Member

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    If you've ever driven a stick shift, regen is quick to get used to.

    I wonder why it disengages at around 5 mph. Regenning to a full stop and then automatically engaging brake hold might take a little practice, but would be a nice option.
     
    • Like x 1
  10. evp

    evp Nerd

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    It sounds like you have "creep" turned on. Go to Controls->Driving->Creep and select OFF.
     
  11. Saghost

    Saghost Active Member

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    Remember, we have induction motors, which means you need a slip between the motor and field speeds to transfer power either way, and the magnetic fields aren't static. In regen, the motor has to be turning faster than the magnetic field is spinning.

    I think it stops at 5 mph because the hardware can't effectively generate power below that speed. Tesla could give you the feeling of regen down to zero by powering the motor in reverse a little, but it would be consuming more power not absorbing more at the end and they chose not to.

    I'm still not sure if the Bolt's regen to 0 is authentic - they have different hardware, which requires a slip angle rather than a speed differential, so in theory it might be possible to go to 0 - but it's equally likely that they are blending brakes into it; the car does regen on brake pedal application as well, unlike Tesla.
     
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  12. Haxster

    Haxster Member

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    #12 Haxster, May 3, 2017
    Last edited: May 3, 2017
    Creep is off. (Why would any experienced driver want this ICE car defect?)

    Regen stops at ~5 mph and then it "coasts". I'd like it to brake "with finess" after regen ends and then hold.

    AP already does this.
     
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  13. Haxster

    Haxster Member

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    No. Not reverse power; just a smooth friction brake & hold after regen gives up slowing the car down.

    AP already does this.
     
  14. Saghost

    Saghost Active Member

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    That'd be another design option, with an implicit linking of brakes to the accelerator. Tesla opted not to take that approach, either, at least so far. Clearly there a few ways the could choose to play this. My point was that they don't extend regen to 0 because they can't, so extending the regen feeling to zero would involve coupling in another system somehow.
     
  15. Haxster

    Haxster Member

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    …like when AP brings the car to a full stop. :)
     
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  16. Saghost

    Saghost Active Member

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    AP also uses the friction brakes at other times - and often throws away energy by waiting too long to slow, then having to brake instead of regenerating.

    I like AP/TACC on empty roads and in really heavy stop and go traffic - most places in between it still annoys me. :)
     
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  17. BrettS

    BrettS Member

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    I posted this yesterday in another thread, but it was kind of off topic there and I think it bears repeating here...

    ---------------

    Just to preface this, I'm coming from a Prius and I've had my model S for about a month now. But I'm really not sure why the gas pedal is the right place for regen. On the prius as you hit the brake pedal it uses regen first and if you call for more braking than regen can provide it keeps regen on and also applies the 'real' brakes. You hit one pedal to brake and no matter how hard or soft you hit the pedal the car gives you the max regen and also ensures that car is still slowing down as much as you want. With 'one pedal' driving then you get regen as you let off of the gas pedal, but it only provides limited stopping power. If you want to stop faster than regen allows you still need to hit the brake pedal. It's counter intuitive.

    Putting regen on the gas pedal creates two issues. First, is an efficiency problem... it's most efficient in a car to coast, regen is nice in that it recovers some power that would otherwise be lost by braking, but a decent amount of power is lost to heat as it gets transferred back to the battery. If you see a red light coming up in the distance you will save the most energy by coasting (no power applied to the wheels and no regen happening) as soon as you see the red light... if the light turns green before you get there, then hit the gas again and you won't have lost any power to heat. If the light is still red when you get there then you will be going slower than if you kept applying power to the wheels and you will still need to brake, but you will lose much less energy than if you had to brake at a higher speed. Of course it's still possible to coast in a one pedal configuration, but you need to hold your foot on the pedal the whole time and keep it pressed down just enough to prevent regen from kicking in and still not provide power to the wheels. It's much easier if you can just keep your feet off of both pedals if you don't want to apply power to the wheels or regen.

    The second issue I see is a psychological one. If people get used to driving with one pedal (especially if the one pedal can bring the car to a full stop) then I'm afraid that in an emergency situation people won't think to actually hit the brake pedal to stop the car faster. If you get used to lifting your foot off the gas pedal to stop the car and all of a sudden someone pulls out in front of you then your natural reaction is going to be to pull your foot off the gas pedal and not hit the brake and that's not going to slow down the car nearly as fast as stomping on the brake pedal. I'm not sure people like me, who have been driving for 25 years now will ever get out of the habit of stomping on the brake in emergencies, but I think this could be a real problem for new drivers who learn on a 'one pedal' car and rarely, if ever, actually use the 'real' brake pedal.

    I think having one pedal to go and one pedal to stop makes much more sense. The brake pedal should be used to stop the car and should use regen as much as possible when you press it.
     
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  18. scottyd

    scottyd Member

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    I'm coming from a Volt, which had a really smooth integration of regen with the brake pedal. Although I kept the car in "L", which maximized regen when you let up on the accelerator, I still had to use the brake in most driving. Based on that I thought I would miss the brake-regen when I got my X.

    So far my X is different, in a good way. The regen is much stronger, and applies at lower speeds (< 10mph) when the Volt regen would fade out. So far I find I rarely need the brake, and love true one-pedal driving.

    One the many positive surprises so far...
     
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  19. smocfi

    smocfi Member

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    Lots of interesting feedback here. The poll so far completely blows me away, almost all votes for Standard. I'm going to try Standard regen tomorrow, see if I can stomach it.

    The thing is, minimal regen (low) braking seems to mimic all the driving I've done in the past, and feels very natural and intuitive. With Standard, I have to keep adjusting the accelerator to maintain my desired speed, it's like I'm driving a stick in 2nd gear all the time. But again, I'll try it again tomorrow, and see if there's something I've been missing or can get used to.

    One comment in this thread suggested that instead of low and standard, there should be a sliding scale of adjustment, so you could choose whatever level of regen you want. That would be good. Or, there could be a mode that adjusted regen based on speed, so that at higher speeds, less regen would be applied, and at lower speeds, it would be stronger. Or maybe the inverse.
     
  20. ohmman

    ohmman Maximum Plaid Member

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    Standard regen just requires that you learn to feather the pedal. Rarely do you just remove your foot completely, you let off as much as you need to slow. One drive on a hilly, curvy mountain road with standard regen and you'll understand why it's vastly superior. You don't need to move your foot back and forth. I often try to make those mountain drives without ever hitting the brake. I've done it over Trinity Road between Sonoma and Napa Valleys, which has an elevation gain around 2000 ft.
     
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