Prius engline idle at full battery charge?

Discussion in 'Gen 4 Prius Technical Discussion' started by Zorrord, May 22, 2020.

  1. Zorrord

    Zorrord New Member

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    Just wondering if anyone else has noticed that on a north american factory prius 2, after braking sufficiently to charge the battery to max, when sitting idle the ICE cuts on for no apparent reason. Just trying to understand the reasoning for this. The EV button (A joke on this model) says "EV not available" if I recall correctly.
    What's that about?
     
  2. alanclarkeau

    alanclarkeau Senior Member

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    It'll be to do with the computer sorting out the temperature of either battery or inverter. Just let it happen, it's normal - it's protective.
     
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  3. Mendel Leisk

    Mendel Leisk Senior Member

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    Last summer I noticed on a hot day, engine running at idle sometimes, even with good hybrid battery charge.

    3rd gen, but same principle I think.
     
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  4. alanclarkeau

    alanclarkeau Senior Member

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    Yes, happens here during summer - only 15°C max today.
     
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  5. FuelMiser

    FuelMiser Senior Member

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    The engineers at Toyota have a reason for this behavior, but they can't tell anyone. All we can do is guess...just assume it's normal and don't fret over it.
     
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  6. alanclarkeau

    alanclarkeau Senior Member

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    Yes - though there are sensors for the temperature for MG1, MG2, Inverter and Hybrid battery, as well as the battery intake air temperature.

    TOYOTA have advised:
    upload_2020-5-23_22-20-9.png
     
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  7. fotomoto

    fotomoto Senior Member

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    The computers are adjusting the SOC on a warm/hot pack. Batteries do not like being hot or being too full and especially both at the same time. If the regen had continued, the ICE would have started running even sooner and longer. This is not a "bad" thing.

    Many folks are concerned about gas usage when this occurs but the MG (to use up that excess charge) is simply spinning the ICE so fast it sounds like it's running.* Using 3rd party software/hardware to monitor the vehicle shows no fuel usage. You could try using "B" mode next time on that same route and see if this stops or changes things at that next stop. Also, this behavior may not happen during cooler weather.



    *Like most things in life, there are times of exceptions. For example if ICE is cold, then gas may be used to complete warmup cycle.
     
  8. Zorrord

    Zorrord New Member

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    I see...interesting. Thanks!
     
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