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HV using EV capacity

Discussion in 'Toyota Prius Plug-in' started by john1701a, Apr 9, 2012.

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  1. john1701a

    john1701a Prius Guru

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    This weekend was my first opportunity to find out what actually happens over an extended distance over a variety of roads. 60 miles of driving with only a single charge, the first 9 of which were at 70 mph. That meant using the HV/EV toggle button to preserve EV capacity for use later.

    After that initial highway drive, it slowed to 55 mph, then 50, then a very long stretch at 30. That's when my curiosity peaked. Would the system automatically take full advantage of the EV capacity available, even though I was still in HV mode?

    Turns out, it does... which is a wise design approach, since STEALTH mode is the most efficient use of overall resources.

    In other words, you can drive and drive and drive in the Eco-Meter's green zone with a seemingly endless supply of electricity, quite unlike the usual distance limitation of the regular model Prius.
    .
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  2. bisco

    bisco cookie crumbler

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    love it, thanks john!
  3. CraigCSJ

    CraigCSJ Member

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    John, are you saying that if you drive in HV with EV miles showing, and are below a certain speed, the system uses up the EV miles? If so, what is the speed below which this happens? When it happens, how is it different from pure EV driving? Does the ICE come on for acceleration, then when cruising speed is reached go off for battery propulsion?
  4. andyprius

    andyprius Senior Member

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    As my neighbors 4 year old used to say, "This is so citing!" :D
  5. john1701a

    john1701a Prius Guru

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    It works exactly like STEALTH mode works in the regular Prius.

    46 MPH is the maximum speed and EV is available until you hit white, the same way my 2010 did it...

    [​IMG]

    ...then in white, the engine runs until you return back to green.

    Also, it won't deplete entirely. That stops at 0.1 miles and holds the last remaining bit of electricity until you switch to EV mode.
    .
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  6. LenP

    LenP Member

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    Ok John this is my first Prius. Are you saying if you start out in HV mode when you drive under 46 mph you can use up your EV portion of the battery then also use up part of the HV portion? Sorry for being so obtuse but stealth mode, I'm guessing is the slow electric start in a regular Prius for the first mile.
  7. Jeff N

    Jeff N Senior Member

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    I'm still a little confused.

    When you have a charged up battery, does HV mode ever act like a "hold" mode where it retains the battery for later use in EV mode? I think you are saying it depletes the battery when running without the gas engine under 40-something mph and does not regenerate that power using the gas engine. Does battery charge get used without regeneration when driving (often at higher speeds) when the gas engine is already running? How is this behavior different from EV mode -- is the gas engine just more likely to start?

    My guess is that you are saying that HV acts like a battery hold whenever the gas engine is already running but depletes the battery like EV mode when the gas engine isn't needed although it restarts the gas engine more aggressively than EV mode.

    Is that right?
  8. seilerts

    seilerts Battery Curmudgeon

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    Is this why a lot of people get 60-70 MPG per tank and arrive at their destination with EV miles still banked, since they travel at high speed on the highway, while someone else with a low speed commute can get 100 MPG even though they have 30 miles between charging opportunities? I know I have been channeling Clausius and beating this to death, but I hope it is clear that the best fuel economy will be obtained if EV miles are close to zero every time you go to charge it.
  9. john1701a

    john1701a Prius Guru

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    Simple.

    When the engine is off, it depletes regardless of mode.

    When the engine is running and warmed up, capacity is retained & replenished.

    The term "STEALTH" came about to indicate when the engine is off, even though you aren't actually driving in EV mode, since the speed & power thresholds are different.
    .
  10. andyprius

    andyprius Senior Member

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    On previous generations Pulse and glide was obtained by bringing the vehicle up to a certain speed. For me I liked 41MPH, at the glide portion NO energy is used. Now in stealth, I think John is saying that you can bring the car up to 46 mph and only the EV portion will be used. I know that the owners manual says 62 mph on EV, but that would be not efficient and deplete the EV portion very quickly. My interpretation of what John is saying is that when the EV is almost depleted, at that point more EV miles can be regenerated AND, is looks like the car can just be left in EV all the time and it will automatically go into HV when the computer determines this. Since all my suburban drives are in the 35 - 45 mph range, this works out perfectly. I'm sure Toyota had this in mind. :cheer2:
  11. john1701a

    john1701a Prius Guru

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    engine: warmed up

    speed: < 46 mph

    energy: green zone

    mode: HV

    That's when EV capacity is depleted without actually being in EV mode.
    .
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  12. 9G-man

    9G-man Active Member

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    What John is saying is very interesting and simple; but first a terminology review is warranted for the first time owner.
    In a regular Prius (or PiP in HV mode, for this discussion)
    "Glide" meant moving along ,with no power flow, below 46mph
    "Stealth" meant moving along, with electric only power flow, below 46 mph. (lasting only a short distance) These are very different states of operation, but often referred to wrongly or with confusion.

    OK,
    So what he is saying is the Pip in HV mode, below 46 mph can "Stealth", almost endlessly, because it's depleting EV capacity to do it. It acts like the regular Prius, but now has unlimited capacity to do it.

    That's interesting and I think explains some things others have experienced.
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  13. cycledrum

    cycledrum PSOCSOASP

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    John,

    Little off topic, but do you have a 1 minute consumption MPG bar graph snapshot in HV, cold start?

    First 5 - 10 minutes on highway, 65 ish MPH, ICE from cold start would be awesome.

    Just wondering how MPG are when ICE warms up.


    TIA
  14. john1701a

    john1701a Prius Guru

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    Yes, but it's really situation dependent. Stay tuned.

    If you fire up the engine prior to the ramp... if you need to accelerate uphill or downhill... if oncoming traffic is traveling slow or fast... if you are already cruising at the time... if you encounter a stoplight before warmup is complete...

    MPG is very similar to the regular model, perhaps a little better since there's a battery benefit with Li-Ion over NiMH.
    .
  15. cycledrum

    cycledrum PSOCSOASP

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    I hope so. 3rd gen ICE warm up seems to be quite the drag on '10 minute trip' FE.
  16. Jeff N

    Jeff N Senior Member

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    In a non-plug Prius in HV mode the small usable 300-500 Wh battery buffer is replenished from the gas engine. In the PiP, I assume STEALTH will use as much battery charge as exists which may be way more than 500 Wh.

    In the PiP in HV mode, when the gas engine restarts (due to speed, acceleration, etc.) does it replenish the battery charge within a new 300-500 Wh buffer based on the battery SOC when the gas engine restarted (in other words, does it establish a new HV gas engine hybrid battery buffer "hold" position) or does it replenish the battery charge all the way back to where it was when STEALTH mode was entered which may have been way more than 500 Wh ago?
  17. 9G-man

    9G-man Active Member

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    Didn't he answer this here:




    And Here:




    And others have indicated that if left in HV mode the car tends to use regen etc to sustain basic HV charge levels,
    when switched to EV mode it will use regen to replenish EV charge level
  18. hill

    hill High Fiber Member

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    I know it's spring now - but it'll also be interesting to see how the mpg's go during 1st 10 minute cycle. How will the PiP act during cold winter / warmups using an EBH.
  19. giora

    giora Active Member

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    I have the impression that like the regular Prius, the PiP ICE can be stationary (0 RPM) only up to 46 MPH no matter what mode you are using (HV or EV).
    The EV capability of the PiP between 46 and 62 MPH is probably achieved with ICE spinning (no gas).
    Anyone checked this?
  20. john1701a

    john1701a Prius Guru

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    0 RPM up to 62 MPH. You can see > 46 video footage here... http://priuschat.com/forums/toyota-prius-plug-in/105347-phv-prius-owner-videos.html

    .
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