MPG in Hybrid Mode

Discussion in 'Prime Technical Discussion' started by CEJ, May 13, 2019.

  1. Salamander_King

    Salamander_King Senior Member

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    Does it run heat using the heat pump or using only engine heat, that is under the condition when AC is set to OFF and AUTO remains ON?
     
  2. Tideland Prius

    Tideland Prius Moderator of the North
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    I don’t know for sure but I assume that condition is separate from whether you run in AUTO or manual. It simply depends on whether it can supply the heat you’re requesting - that will determine whether it runs the engine or not.
     
  3. Salamander_King

    Salamander_King Senior Member

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    AUTO or manual is not what I was concerned. My assumption was that by "AC" Toyota meant the use of the electric heat pump or air conditioner similar to the "AC" on the fob for remote climate control. So, by turning AC OFF, I was thinking the car will not use the heat pump nor air conditioner, either AUTO or manual. But of course that means, if the heat is needed for the set temp and the car is running on EV mode, it will have to turn on the ICE. This should be easy to test. I will give a try on my way home today.
     
    #323 Salamander_King, Sep 4, 2019
    Last edited: Sep 4, 2019
  4. Tideland Prius

    Tideland Prius Moderator of the North
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    Oh I see what you mean. In this case, I believe A/C is the electric compressor and not the heat pump. (For dehumidification in the winter)
     
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  5. Salamander_King

    Salamander_King Senior Member

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    OK, that means "A/C" on the display has a different meaning from "A/C" on the fob. I just searched but I couldn't find clear distinction of those two usages anywhere in the manual. o_O
     
    #325 Salamander_King, Sep 4, 2019
    Last edited: Sep 4, 2019
  6. Tideland Prius

    Tideland Prius Moderator of the North
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    Yes lol.
     
  7. Salamander_King

    Salamander_King Senior Member

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    OK, I tried AUTO ON, A/C OFF, set temp HI on my way home. Yes, as @Tideland Prius said, it did turn on the heat, but ICE did not come on. Thus it does use the heat pump even with A/C off. I also set the temp to LO. Cool air was blowing from the vent, but I think that was just ambient fresh air. Outside temp was 65F.
     
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  8. CEJ

    CEJ Member

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    Great and interesting info. Thanks to all of you!
     
  9. Salamander_King

    Salamander_King Senior Member

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    As I commented in the later on this thread, keeping A/C OFF does not turn off the heat pump. The heat pump will come on if the heat is needed for the set temperature. As @Tideland Prius explained, "A/C" on the screen means electric compressor for the air conditioner (cooling or dehumidifying) unlike the "A/C" on the fob which include the heat pump for heating purpose.
     
  10. CEJ

    CEJ Member

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    So if everything in climate control is turned off except direction of air flow and you are in EV mode, the heat pump will supply heat if required by the temp setting even though the temp setting is not even visible?
     
  11. Salamander_King

    Salamander_King Senior Member

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    That would be my guess, but you also have to have the fan on at some level. If the fan is all the way down showing no bar, then entire climate control is off, I think. Of course, I would not know when the heat pump comes on. There is no indicator that turns on with the heat pump AFAIK. BTW, if you have done HV drive prior to switching to the EV mode, and the climate control needs heat, it does make use of engine heat despite the fact you are now on EV mode. I can feel the difference in temperature of air coming out of the vent with ICE previously on prior to EV mode vs no ICE.
     
  12. CEJ

    CEJ Member

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    Thanks, as always, SK. I had the fan off and thought maybe I felt some heat, though I am not sure. Need to research this more thoroughly. Am I remembering correctly that only the Prime has a heat pump and the regular Priuses do not? Probably requires the bigger battery to run the HP.
     
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  13. CEJ

    CEJ Member

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    BTW once the fan is on, the temp setting becomes visible which suggest you are right that when the fan is off there is no heating since temp setting is not visible.
     
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  14. Salamander_King

    Salamander_King Senior Member

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    I think I have felt warm air coming out of the vent when I had a fan off. This often happens in my car when I am driving on a cold morning with HV for a while with heat on, then turn the entire climate control off (thus fan is off) and switch to EV. Even without forced air circulation, the direction of flow is such that warm heated air from ICE comes through the HVAC system, so it seems.

    And yes you are correct PRIME is the only model with a heat pump.
     
  15. CEJ

    CEJ Member

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    The heat I thought I felt occurred during EV only driving, but need to check it out further. Hard to believe there could be heat in this case with no temp setting visible.
     
  16. Salamander_King

    Salamander_King Senior Member

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    Was outside temp colder than cabin temp? I wonder in the absence of ICE firing up if there is no other heat source to be diverted to HVAC system.
     
  17. vvillovv

    vvillovv Active Member

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  18. CEJ

    CEJ Member

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    Not for sure, but probably was colder out than in.
     
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  19. CEJ

    CEJ Member

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    Can you remind me, in HV mode does the heat come only from ICE or is it a combination of ICE and the HP?
     
  20. Salamander_King

    Salamander_King Senior Member

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    That, I don't know the answer. As I commented, there is no indicator that comes on when the heat pump is on. Knowing how the PRIME is designed, I would think whatever the most efficient way to deliver the desired heat is used. That means, as long as ICE is on and there is available wasted heat to be used, the heat pump should stay off. But I am only guessing here.
     
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