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Finally!

Discussion in 'Gen 2 Prius Fuel Economy' started by Whatsthat, Oct 8, 2005.

  1. Whatsthat

    Whatsthat New Member

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    Finally greater than 60 MPG.....

    I have been feeling like an idiot, I have not been able to get better than 51 MPG. It was at 75 degrees today for the first time in 4-5 months. Normally in south Georgia the high has not been below 90-95. I was able to drive without the AC. I also finally figured out that if I accelerate briskly to speed, let off the gas (2 seconds) and then try to maintain 60 MPG+ on the MFD going about 55-60 MPH the car will maintain that speed. It will accelerate on flat ground or down hill and will loose a little speed going up hills. 120 mile trip with 7 stops at various stores and 60.11 MPG

    I also figured out that in town driving using the electric mode is desirable. I was able to go several miles on EV and light breaking for traffic. I was under the impression that EV was bad (had to recharge the battery somehow) however, I guess the mild breaking in town traffic is enough to keep it charged. Several 5 minute bars above 80 MPG.

    I am sure this is old news to most of you pros but it was the first time I was able to do it.

    In the past I would try to watch the arrows and minimize the regeneration or I would simply use the cruse control. I was able to do much better than the cruse control today.
     
    #1 Whatsthat, Oct 8, 2005
  2. Vincent

    Vincent Don't Wait Until Tomorrow

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    Automatic EV, or do you have an EV switch?

    Thanks
     
    #2 Vincent, Oct 8, 2005
  3. Whatsthat

    Whatsthat New Member

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    I do not have an EV switch. I was refering to the gold arrows only....
     
    #3 Whatsthat, Oct 8, 2005
  4. TonyPSchaefer

    TonyPSchaefer Your Friendly Moderator
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    I will never see 60MPG again!

    Not until next summer.

    All this week, I had been milking 56MPG and considering the temperature drop was darn proud. This afternoon after a few errands I noticed 55.1 and almost yelled.

    Congrats on hitting 60. It's a great feeling.
     
    #4 TonyPSchaefer, Oct 8, 2005
  5. micheal

    micheal I feel pretty, oh so pretty.

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    Congratulations! Sounds like you have made a breakthrough!

    In my understanding, it is not that ev mode is necessarily bad, just bad in most cases to focus on that. If you have a route where you know you will make up the battery charge (like having a long downhill or a stoplight you can always have to regen up to) then go ahead and use that battery. In general for me, I try not to focus on getting EV mode, except for a few exceptions, since just having the ICE run as low rpm as possible to maintain speed is pretty good mpg, if warmed up.

    I have noticed since I have focused more on feathering the gas though, that the computer puts the car in ev mode more. This isn't a big deal, I just make to sure to use regen when keeping up to the stoplights and such.
     
    #5 micheal, Oct 8, 2005
  6. gcoyne

    gcoyne New Member

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    Is there anyway to tell when you are using friction braking in addition to the regenerative braking?

    george
     
    #6 gcoyne, Oct 9, 2005
  7. Vincent

    Vincent Don't Wait Until Tomorrow

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    Yes, your foot is on the brake.
     
    #7 Vincent, Oct 9, 2005
  8. TonyPSchaefer

    TonyPSchaefer Your Friendly Moderator
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    haha. That's exactly what I was thinking.

    gcoyne, perhaps we don't understand the question.
    Or perhaps you've gotten wrapped up in the whole regenerative thing.
    1) Regenerative braking occurs every time you lift your foot from the accelerator. You can feel the drag of the wheels turning the electric motor in orer to generate electricity and recharge the battery.
    2) Additionally, there is engine braking in which you have to shift into and you can hear the engine revving to create drag and slow the car down. During engine braking, the wheels are still turning the electric motor.
    3) What people around here call friction braking is simply brake pads clamping the rotors. But again, since the front wheels are turning, they are again being used to turn the electric motor and recharge the battery.

    You can rest assured that unless you have slipped into Nuetral or mastered the art of "feathering", pretty much every time you lift your foot off the accelerator the car will start trying to recharge the battery. And every time you press your foot on the brake, just like any other car, you are engaging friction braking.

    Now, either I've taken strides in clarifying the matter or you're ticked at me for questioning your Prius knowledge. I sincerely hope it's the former.
     
    #8 TonyPSchaefer, Oct 9, 2005
  9. LaughingMan

    LaughingMan Active Member

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    I think this is an incomplete explanation. If you are at cruising speed, and you let your foot off of the accelerator, the car will start to regen, but this is a 'coasting' regen. This does not provide very much regenerative braking, and it will take you a very long time to recharge your battery even if you were able to sustain coasting.

    When you step on the brake pedal, it's not certain whether or not the hydraulic brake pads actually close. Really it depends.

    If your speed is slow, say less than 8MPH, the system infers that you are close to stopping your car, and will engage the brakes.

    However, at higher speeds, it doesn't necessarily engage the pads no matter what. Instead, it ramps up the braking force provided by the MG2, meaning MORE regen, and more of a chance to recharge the battery.

    In an emergency stop at higher speeds, it engages the hydraulic brakes immediately.

    Not every time you step on the brakes do the hydraulic brakes engage. It depends on how hard you step on it, how fast you are going, etc.
     
    #9 LaughingMan, Oct 9, 2005
  10. gcoyne

    gcoyne New Member

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    Thanks, LaughingMan. I thought that the braking worked as you describe it. Now, is there any way to tell whether friction braking is activated?


     
    #10 gcoyne, Oct 9, 2005
  11. Vincent

    Vincent Don't Wait Until Tomorrow

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    Is That Really the Way the Brakes Work?

    Wow, I'm surprised (concerned) that the service brakes can be over-ridden by the HSD; is that really the way the brakes work? Where does it explain that feature?
     
    #11 Vincent, Oct 9, 2005
  12. Maytrix

    Maytrix Member

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    I don't remember where I saw it, but I saw a good chart that showed how it works. From what I gathered from it, your hydraulic brakes don't engange until the brake pedal is depressed that last 90% of the way. The rest of the time is all regenerative.

    The chart displayed pressure on pedal and then showed how the pressure affected usage of the regen or hydraulic brakes.
     
    #12 Maytrix, Oct 9, 2005
  13. LaughingMan

    LaughingMan Active Member

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    I think Evan posted it before the apocalypse of two days ago.
     
    #13 LaughingMan, Oct 9, 2005
  14. Vincent

    Vincent Don't Wait Until Tomorrow

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    EVAN, Please Post the Brake Chart Again

     
    #14 Vincent, Oct 9, 2005
  15. tomdeimos

    tomdeimos New Member

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    It is simple to tell when the brakes are engaged. Just open the window and listen.
    You can hear the brake pads scraping easily.
     
    #15 tomdeimos, Oct 9, 2005
  16. efusco

    efusco Moderator Emeritus
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    [​IMG]
    There you go. BTW, there is more to this braking thing. I don't have time for a detailed explaination, but it's a very good very safe system with triple redundant back-up/fail-safe.
     
    #16 efusco, Oct 9, 2005
  17. tt823

    tt823 New Member

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    Congratulation on your above 60mgp!!!! :D
     
    #17 tt823, Oct 12, 2005
  18. ScottY

    ScottY New Member

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    Can Dr. Evan (if you have the time) or someone else explain what's the ECB (Electronic Control Brake) effect and expanded regen range? How's the expanded regen range different from the normal regen range?
    AND how do you guys find out so much?!
     
    #18 ScottY, Oct 12, 2005
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