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Low temps and Auto/HV modes

Discussion in 'Gen 5 Prius Technical Discussion' started by Rafsdhc6, Nov 18, 2023.

  1. Rafsdhc6

    Rafsdhc6 Junior Member

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    I have a short commute of around 6-7 miles one way with a quick portion of it is on the highway. The Highway is a quarter mile away from my house.

    Usually I just cruise on EV but sometimes I do have to be quick as it’s a busy stretch so I’ll set it to Auto. My question from engine longevity stand point and low temps going well below 20f, should I just switch to HV and let the engine warm up before I’m on the highway or keep it on Auto and let the engine warm up during highway acceleration?
     
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  2. bisco

    bisco cookie crumbler

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    i would switch to hv right away. it has pretty much been determined that auto was useless on gen 4 and likely no better now.
    there haven't been a lot of gen 4 problems, but if you intend on keeping the car, the engine will survive much longer if it is properly warmed up whenever needed for acceleration.
     
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  3. BiomedO1

    BiomedO1 Senior Member

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    I'm with Bisco on that one; engine should be warm when you demand power from it. On my 4th gen; you need to get over 80 mph, 128 Kmh for the ICE to kick-on. My understanding is that you have a larger engine and battery (capable of 40 miles), in your gen5. You should be able to manage your commute without using your ICE - unless temperatures drops below optimum battery usage conditions. In that case, the ICE will simply turn-on.
    IMHO, if you park your car at work or home and the ICE is running; I would probably let the car complete it's warm-up phase before shutting-down the motor.
     
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  4. Louis19

    Louis19 Active Member

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    I would suggest to switch to HV right away for engine warm up and cabin heating because below 20F the heatpump will struggle and suck alot of electricity just to try to warm up the cabin . When the engine is warm and the cabin is cosy then flip to EV mode.;) the engine is a very efficient heat generator.
    For short trips , of a few kilometres ,where the engine would not have enough time to warm up enough , keep it in EV and switch on the seat and steering heaters :cool:
     
    #4 Louis19, Nov 18, 2023
    Last edited: Nov 19, 2023
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  5. Trollbait

    Trollbait It's a D&D thing

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    It is a 7 mile trip. If the engine has to come on for extra heating or defogging, I'd just leave it on for the whole trip to give more time for moisture to be driven out of the oil.
     
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  6. Rafsdhc6

    Rafsdhc6 Junior Member

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    I occasionally enjoy spirited driving and I find the Auto mode on Gen5 really nice, cuts out the engine noise considerably while having lots of power for passing.

    But it makes sense to warm up the engine before hand. I was secretly hoping when in Auto the oil would be secretly heated and ready for acceleration :D
     
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  7. Louis19

    Louis19 Active Member

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    I would stay away from using AutoEV mode in cold weather ....well finally all the seasons . Stick to EV or HV.
     
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  8. Louis19

    Louis19 Active Member

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    I really like your secretly hopes......when I acquired my prime in 2022 ...I realized that this car was a saucerfull of secrets :D
     
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