About regen and why Tesla made it wrong

Discussion in 'Gen 4 Prius Main Forum' started by peter, Jan 13, 2022.

  1. peter

    peter Junior Member

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    Regeneration is about using surplus kinetic energy to charge the batteries. That is instead of breaking
    with the braks use the electrical motor(s) to reduce speed and use the energy obtained to charge batteries.

    Prius has a intelligent system with sensors in the break system. When break pedal is pressed
    the car will use the engine to reduce speed as long as it is enough. When breaking more then
    the engine can use the hardware breakes ( rotors) will be engaged. The switchover is unnoticeable
    and smooth , the only exception is first generation where this could be experienced. Since then
    toyota has done a good job to make breaking smooth.
    Tesla on the other hand totally lacks the breaksystem sensors, whenever the break is pressed the
    mechanical breaks are used, instead Tesla relies on the accelerator pedal's position. when released
    it will break with the engine and regen. This in it's extreme will be known as "one pedal driving".
    I find this obsessive, being forced to have one foot partially pressed all the time is on the limit
    to be painful. ( Tesla make many things very well, this is not Tesla bashing !)

    Prius also has regen when accelerator is released, and this is (in my opinion) totally wrong. When i
    release the accelerator i want to "freewheel" , that is continue with me current speed until i
    either press the break or press the accelerator.
    This opens for a configurable option ( there is already a number of things that the owner can adjust ) :
    a menu where i can decide if i want any regen when i release the accelerator, and if so how much.
    This may give the people that likes "one pedal driving" to experience that or, for others give them
    a chance to experience "the right way". One variation on that theme could be "regen if speed increases"
    such as when traveling down hill ( i'm not convinced but i may be wrong here )

    Opinions ?
     
  2. Leadfoot J. McCoalroller

    Leadfoot J. McCoalroller Senior Member

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    It has long bugged me that the cheap little Prius has a fancy, sophisticated brake blending system, while the expensive Tesla cheaped out and just has straight brakes.

    If we had a car allowing braking mode selections or configurability, we would use it to match the behavior of the least-configurable car in our garage. It's nice getting more energy efficiency but in our use that would always take a back seat to the safety offered by consistent behavior across shared cars.
     
  3. sam spade 2

    sam spade 2 Senior Member

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    There is no "right way".
    You are expressing a personal preference and you should not expect the makers of products to conform to your opinion.
    I am on my 4th hybrid now and never considered the braking action to be "one pedal driving".
    It is not that much different from what I have been doing for about 60 years with a conventional gas engine.
     
  4. bisco

    bisco cookie crumbler

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    i don't think there is any way to compare a bev with a hybrid. in the pip, with ev only, the regen system is very comfortable for me.
    one pedal driving, that might prove difficult for the general public whohave difficulties with two pedals and a steering wheel.
    myself, i would prefer paddles
     
  5. Zythryn

    Zythryn Senior Member

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    It really is a subjective preference.

    I prefer the one-pedal driving. I find it far more convenient, as well as safer.
    In the Tesla, the driver does have settings to control the amount of regenerative breaking. If someone prefers breaking only on the brake pedal, they have that option.
     
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  6. fotomoto

    fotomoto Senior Member

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    Simple muscle memory takes affect within a few drives. No different than pedal mapping in pwr and Econ modes.
     
  7. peter

    peter Junior Member

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    The customer is always right !! Remember that ?
    I am a customer and i express my preferences, i would like "no regen when accelerator is released".
    I admit that other persons have other preferences, what i am asking is configurability of my car .
    ( i am on my 5'th prius and second tesla )
     
  8. kevinwhite

    kevinwhite Active Member

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    Toyota had many years where the blended breaking in the Prius was the cause of terrible break "feel". The unblended approach used by Tesla gives a better driving experience in my opinion.

    The Gen2 Prius was particularly bad in this respect. Many of us here have experienced the feeling that the breaks have failed when the tires encounter a small bump or slippery patch and the braking system has to quickly readjust the blending ratio. I now have a Gen 4 and it seems much better, but that has taken 10 years of development to do.

    Regarding having to hold the pedal at a fixed position, I find the Prius more difficult than the Tesla to hold at the coasting point.

    kevin
     
  9. peter

    peter Junior Member

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    No. Most Teslas can choose between strong and weak regen. No tesla ( as i know ) can disable
    regen , and that would disable all regen as the tesla lacks needed hardware.
    Some tesla 3 is aid to have lost the ability to adjust regen( i have not experienced that myself thus
    it's unconfirmed).
    This is no Tesla thread, let's talk about Toyota.
     
    #9 peter, Jan 13, 2022
    Last edited: Jan 13, 2022
  10. Zythryn

    Zythryn Senior Member

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    Weak regen is such light regen it is basically off.
    If you wish to talk Toyota only, I would suggest you not bring up Tesla;)

    On my gen II Prius, the blended braking was poor. I am glad to hear that has been improved.

    I agree with you that use options are good. I suspect government regulations may cause manufacturers to limit options that can affect efficiency.
     
  11. ChapmanF

    ChapmanF Senior Member

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    As some others have already pointed out, you could be overstating how "unnoticeable and smooth" Toyota's implementation is.

    The main trouble spot has always been when you are lightly braking, the ECUs have agreed on a certain regen strategy, and then you hit some sort of road irregularity that forces the ECUs to quickly renegotiate the chosen strategy and include the friction brakes.

    To my knowledge, people have been noticing and complaining about that in every generation of Prius. If you are not used to it or expecting it, you think for an instant that your brakes have let go.

    When I first bought my 2001, it was explained to me here on PriusChat, and recommended that I go drive some weird road patches and repeat until I was used to it. I got used to it quickly and it never startles me anymore, and to me it has always felt pretty much the same, Gen 1, Gen 2, and Gen 3. (I haven't driven a Gen 4.)

    People who are not used to it have literally filed NHTSA complaints about it, thinking it is a brake defect. Plaintiff's attorneys bringing suit against Toyota for other issues that might actually be brake defects have indiscriminately included NHTSA complaints about this transition in their filings along with those other issues, because, well, plaintiff's attorneys.

    For the 2010 model year, Toyota issued a firmware update as a recall just to tweak the way the transition felt so it wouldn't upset people so much. My 2010 has the tweak, and still has the transition, just about as noticeable as it always was in Gen 1 and Gen 2. I don't know if that means the pre-tweaked transition in the 2010 was really shockingly worse, or just that 2010 was the first year the Prius really went mass-market and they were getting huge numbers more complaints and couldn't be seen as not doing something.
     
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  12. peter

    peter Junior Member

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    I only had problems with gen 1 where the transition was noticable.
    2 model II, one model 3 and one model 4 all have been smooth and predictable.
    It might depend on breaks condition and driving habits however.
     
  13. sam spade 2

    sam spade 2 Senior Member

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    Sure. It is a big lie.
    If you ever worked in direct customer service/retail you would know that.

    Expressing your preference/opinion is peachy keen.
    Expecting that to actually make a difference is just being naive.
     
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  14. ChapmanF

    ChapmanF Senior Member

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    I have found it absolutely repeatable in any Prius of any year that I have ever driven. That is because it is not a fluke, it is how the system works. Once you know what kinds of road surface elements will trigger it, you can pretty much demonstrate it at will.

    I generally make a point of doing that, any time I am showing someone about driving in a Prius, because familiarity and understanding are the best prevention against being startled by it.

    It is easy to go to NHTSA's web site and search complaints about the brakes. There will be complaints about other issues, of course, but a large fraction of the complaints have always been about that transition effect. There's no evidence those drivers all had something about their brake condition or driving habits in common.
     
    #14 ChapmanF, Jan 13, 2022
    Last edited: Jan 13, 2022
  15. fuzzy1

    fuzzy1 Senior Member

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    While your bicycle truly freewheels, traditional non-hybrids do not (apart maybe from some old freewheeling overdrives). They exhibit a noticeable engine compression drag.

    For drivability reasons, it seems that Toyota was trying to make the Prius feel somewhat like traditional vehicles so that drivers wouldn't need to re-learn too much. A true freewheel would have brought numerous reviewer and driver complaints. Putting in the slight no-pedal regen drag helped make it feel more "normal".

    Yes, I'd like a choice. But that adds to the complexity that would chase off even more potential buyers, so I do feel that Toyota made some reasonable marketing tradeoffs.
     
    #15 fuzzy1, Jan 13, 2022
    Last edited: Jan 13, 2022
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  16. peter

    peter Junior Member

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    I'm grown up with freewheeling SAAB's and find that freewheeling is a natural thing. So does old SAAB
    users . It's just a learning tree.
    I'm not advocating this for everyone, i just want to have it possible for those "that knows".
    That's why a configurable option is of value.
     
  17. dbstoo

    dbstoo Active Member

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    One thing that you should not have in a car is the ability to change the braking behavior. Every time you are faced with an emergency stop the procedure to stop should always be the same and the car's response should also be the same.

    The last thing I would want would be to find out that my wife drove the car last and set it to freewheel where I expect it to slow down over a set distance.

    Long, long ago I used my parent's 1970's Ford LTD to run an errand. My car was 3 on the tree and manual brakes. The folks had an auto tranny and power everything. The Ford surged and died as I entered a 3 lane intersection. I instantly did what I would do in my car. I floored the clutch and tried to put it in neutral gear. Obviously, I screeched to a stop since the "clutch" was actually an 8 inch wide brake pedal. Since then, I've tried to keep all my cars as similar as possible for safety reasons.
     
  18. privilege

    privilege Active Member

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    that user name you picked is awesome.

    what's this about Tesla only have "straight brakes" ?
     
  19. Leadfoot J. McCoalroller

    Leadfoot J. McCoalroller Senior Member

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    I'm sure I could have described the brakes more accurately in my comment, apologies.

    In a nutshell, a Prius has both electric and traditional hydraulic brakes, but both systems are controlled by the same familiar pedal. The computer decides which system to actually employ when you step on that pedal. It's usually right, but it isn't perfect. The overall application served is to allow the average driver to recapture a lot of energy without having to change driving behavior at all. You already know how to step on a brake pedal, and when, and how hard. They've just made it so that your instincts and training will now also serve a secondary purpose to regenerate electricity.

    This is in contrast to the Tesla, which has the same hydraulic brakes you'd find in any ordinary gas car from the past 60 years. Sure, it's got all the modern safeties within that, but they did not even attempt a blended braking system like Toyota.

    Now, Tesla does have a system to allow the driver to interactively operate the regenerating brake system, it just doesn't involve using the brake pedal. This is their single-pedal operation mode. Using it means a little bit of driver retraining is required. It doesn't sound like it is difficult or anything. My only argument against it is that I want consistent behavior across several cars.
     
  20. fuzzy1

    fuzzy1 Senior Member

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    SAAB was a very narrow slice of the market. It would be a strange and unfamiliar sensation for the great majority of North American drivers.
    I'd like this option too. But I also see it as a reasonable decision for Toyota to not increase the user interface complexity by offering this option, not a "totally wrong" decision.
     
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