Is the chg line where friction brakes engage?

Discussion in 'Prime Main Forum (2017-Current)' started by lochnersm, Oct 17, 2020.

  1. lochnersm

    lochnersm Junior Member

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    When I'm braking, I try to keep my braking above the line because that's what I assume is where the brakes engage. Is that accurate? I'm still trying to get better at braking because of my attempt to keep it above that line, I think I'm getting too close to the car in front of me too quickly.

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  2. Diemaster

    Diemaster Active Member

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    Look at my post and the following one here.
     
  3. mr88cet

    mr88cet Senior Member

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    I try to do the same, even if only because that keeps my driving smoother and increases the chances that all braking is regenerative. Nevertheless, I bet the threshold, *under normal braking circumstances*, is considerably lower than that.
     
  4. mr88cet

    mr88cet Senior Member

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    In terms of harder-than-normal braking force there seems to me to be one reason to think that line might be somewhere around where friction brakes kick in: Compare braking force to available acceleration force.

    The maximum available regenerative braking force should be comparable with the maximum available acceleration, but obviously in the oppose it direction.

    The maximum available acceleration force is not huge, so it’s not unreasonable to think it has to kick in at least some friction braking beyond that.
     
  5. ChapmanF

    ChapmanF Senior Member

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    The eco-driving-aid graph on the dash is a synthetic display cobbled up from various parameters in how the car operates; there's nothing about it that translates directly to a telltale for what the friction brakes are doing. Old-time member hobbit got curious enough once to build a dash LED display driven directly by the fluid pressure sensors (and that's kind of how you have to do it, because anything based on reading data from the OBD port will just be working from laggy snapshots, and the braking coordination happens really fast).

    [​IMG]

    What happens in real life is more complicated than a lot of people assume, and typically involves more friction in the mix when you are initially braking at speed, tapered off to more regen as you pass through the sweet spot of speed and braking force, and going back to friction as you roll out to a stop. The graphs from the Toyota manuals can be seen in posts like this one.
     
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  6. Salamander_King

    Salamander_King Senior Member

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    HSI does give you a fairly good indication of your use of friction vs regenerative braking. As you indicated, above the CHG line you are mostly using regenerative braking without engaging the friction brake. Using an app like the Hybrid Assistance, you can watch when and how hard the friction brake engages as you drive. I don't have a video but I am sure @john1701a will share his video to prove the point. In the static view of the HA app shown below, the red arrow is the friction brake use.

    upload_2020-10-17_9-56-47.png
     
  7. john1701a

    john1701a Prius Guru

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    An aftermarket device & app like that can be quite informative. There's a lot that goes into the programming of the system that most people are never aware of. You can make best use of the battery with that added knowledge.

    I try to avoid braking all together. More roundabouts in our area help with that, since slowing down becomes much more predictable. You can see that in this video. There's a mix of green (regen) with red (friction) braking examples. The little pad symbols give you an on-going status.

     
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  8. lochnersm

    lochnersm Junior Member

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  9. Salamander_King

    Salamander_King Senior Member

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    If you are asking about the HA app, then Yes, you are correct. Read a detailed explanation of the icon below.

    Hybrid Assistant: Dashboard
    upload_2020-10-17_10-34-42.png
     
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  10. Flaming

    Flaming Active Member

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    You can't judge by the sound ,The Regen is only on the front wheels so you will always hear the rear brake eat the rust of on the rotors...

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  11. ChapmanF

    ChapmanF Senior Member

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    Generally not when not applied.
     
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