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Auto HV/EV memory?

Discussion in 'Gen 5 Prius Technical Discussion' started by PriusPrimetime, Jul 24, 2023.

  1. PriusPrimetime

    PriusPrimetime Junior Member

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    Should the car "remember" if it's shut off in Auto HV/EV mode? I feel like when I turn the car off in AutoHV/EV mode, it defaults back to "EV Mode" when I start it back up again.

    Or does this button need to be pressed every time I start the car?

    EDIT: Actually, I'll need to test this further. I think I ran the traction battery down to 0 last time, then charged it to full, and maybe that's why it didn't stay on Auto HV/EV
     
    #1 PriusPrimetime, Jul 24, 2023
    Last edited: Jul 24, 2023
  2. bisco

    bisco cookie crumbler

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    In gen 4 it always defaults to ev. There might be a setting in gen 5 if they have changed it
     
  3. PriusPrimetime

    PriusPrimetime Junior Member

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    Doesn't seem like it. I just tested it. Also defaults to EV.

    If anyone know how to change this in a Gen 5 (if possible) PLEASE let me know.
     
  4. KMO

    KMO Senior Member

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    It seems to differ in the US and Europe.

    The US manual says:

    The Europe manual says:

    Not sure this is useful information...
     
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  5. bisco

    bisco cookie crumbler

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    when you turn the european model on in auto ev/hv, does the engine fire up?
     
  6. vvillovv

    vvillovv Senior Member

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    I'd think the european models should start the engine while in EV Auto mode at startup time, for the same reasons the US models will start the engine at startup or just after startup in the default EV mode. Like when switching on defrost or A/C at lower temp setting and higher fan speed. Probably depends of other factors the ECU reads as well.
     
  7. Maxwell61

    Maxwell61 Active Member

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    Has someone any clue about the different point of ICE firing between Auto EV/HV and EV mode?
     
  8. KMO

    KMO Senior Member

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    In the G5, EV mode restrains power to a level that the electric motor can supply - the meter goes up to the midway mark in the Power part of the Hybrid System Indicator that marks the limit of EV operation. It won't run the engine for extra drive power, and if the engine does start, it won't be more powerful. (You can see that in this acceleration test video).

    Auto EV/HV mode does not restrain the power, and will run the engine to reach the maximum power.

    Both modes will start the engine for all the other auxiliary reasons (cabin heat, excess speed, system cleaning).

    I'm not aware of any other real difference between the two modes in the US model. Both modes have a "prioritise charge depletion" heuristic

    In the Europe model (and Japan, I think), there is Predictive EV Drive, which adds more intelligence to Auto EV/HV:

    As I understand it, that requires the destination to be set as it changes the heuristic to "deplete the charge by the end of the route, maximising overall route efficiency". I don't know if it can do anything with just learned data - maybe if it can guess your destination?
     
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  9. KMO

    KMO Senior Member

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    Edit - actually, looking at the Japanese brochure, I'm not sure if it's got Predictive EV Drive for the PHEV - it's not specifically mentioned. But it does describe a different auto-learning predictive mode for the HEV:

    Google translate:

     
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  10. Maxwell61

    Maxwell61 Active Member

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    Thanks @KMO i'm looking to know how many kW are required in Auto EV/HV mode for the firing of the engine.
    I guess we should wait for someone with some OBD device for the measurement.

    Yes, i've read in the manual of my italian version about the predictive EV drive (yes, it seems necessary the on-board navigation and it makes sense) and i'm super curious to understand the logic of the SOC optimization.
    Somehow it shoud be a form of Auto EV/HV mode, the latter being a fixed form for the power limit for the EV condition.

    Some years ago Predictive EV was experimented on the Hyundai Phev for Korea only, but i do not know how effective it was.
     
  11. Maxwell61

    Maxwell61 Active Member

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    This is from my EU/IT manual (translated in English):

    Predictive EV driving

    When using the route driving
    from the navigation system, the
    system automatically alternates between
    EV driving and HV driving based on
    data such as remaining battery charge of the
    hybrid (traction battery) and information
    on traffic and route to ensure
    that the vehicle efficiently utilizes
    electrical energy from the traction battery.
    For example, the system selects the
    HV driving in full power sections,
    such as on highways or uphill stretches.

    Predictive EV driving.
    The system is only available when the following is selected
    the AUTO EV/HV mode.