Prius Prime - Electric Heat-Pump

Discussion in 'Prime Main Forum (2017-Current)' started by john1701a, Feb 8, 2020.

  1. john1701a

    john1701a Prius Guru

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    Here's the latest in my quest to share technical info in a KISS format. The detail is there if you're interested. If not, it's just an entertaining time-lapse video showing what a non-eventful winter commute is like in Minnesota.

    With outside temperature in the teens, the entire drive is in EV. You can easily see the electricity trade-off of range for warmth. It serves well for those driving short commutes or (like me) have the opportunity to recharge while at work.

     
  2. bisco

    bisco cookie crumbler

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    I want one!
     
  3. Marine Ray

    Marine Ray Senior Member

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    John - I posted this newest video on both Facebook PP groups forums this morning. Did you want to do that or are you OK with me posting?
     
  4. john1701a

    john1701a Prius Guru

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    Feel free to spread the word. My focus is setting up for the next filming opportunity. Winter doesn't always cooperate with my schedule.
     
  5. Marine Ray

    Marine Ray Senior Member

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    Thanks John. Your videos are so informative and well done. To me, there is so much to digest and don't normally digest everything if I have time to only watch your video once. Any thought to adding just screen shots i.e. "This shows that the batteries are at XX degrees first thing before I leave the garage which means the battery heaters were on when I had it plugged in overnight." Your screenshot could highlight both the exterior temp and temp of the traction battery. Just a thought...
     
  6. dig4dirt

    dig4dirt MoonGlow

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    Can you tell me about the 84% you started out with (bottom right corner)

    Were you with a full charge and dropped to 84% after cabin warm?
    Or take a short drive running it down, or did you just not charge fully since
    you knew you would have enough to get the charge at work?
    :sneaky:

    In a previous vid, you did mention it was (I think) the actually batt capacity, versus toyo % on mfd?
    Just curious.
     
  7. john1701a

    john1701a Prius Guru

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    That will be coming in the User-Guide currently in the works.
     
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  8. john1701a

    john1701a Prius Guru

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    84% is a full charge (actual capacity). That 16% not accounted for is a buffer for longevity. Charging to 100% shortens battery life. So, the system stops at 84% to prevent the easily avoidable stress.

    The dashboard shows usable capacity, hence saying 100% when charge-level is really 84%.
     
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  9. dig4dirt

    dig4dirt MoonGlow

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    Yes, that I kinda what I thought.

    One more question (sorry)
    In the vid you mentioned 11f for lowest until ICE kicks in.
    I thought it was 14f, or have I been misinformed?


    Thank you again for these videos and the webpage.
    No other source for this kind of knowledge about the Prius/Prime
     
  10. john1701a

    john1701a Prius Guru

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    Technically, it is. But real-world tends to reveal on-paper tolerances have some wiggle room.
     
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  11. PiPLosAngeles

    PiPLosAngeles Active Member

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    I'm curious why your average MPG shows 199.9 for a full EV drive. Mine always displays 999.9.
     
  12. Raytheeagle

    Raytheeagle Senior Member

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    They changed the display ;).

    You must have a 2018 or 2019 as it changed to 999.9 then(y).
     
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  13. PiPLosAngeles

    PiPLosAngeles Active Member

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    I guess Toyota figured knowing your MPG beyond 200 was too much information and action needed to be taken?
     
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  14. Salamander_King

    Salamander_King Senior Member

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    I would like to see how cabin temperature changes with the use of the heat pump at that low temp. My experience has been that the heat pump just did not do much to heat up the cabin temp when the ambient temp is below 20F.
     
  15. Marine Ray

    Marine Ray Senior Member

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    Good point. In our case here in the Lake Tahoe area, I find both the heated steering wheel and seat provide enough warmth without having to run the cabin heating system. I suspect if we had rear passengers then that would be a different story.
     
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  16. Salamander_King

    Salamander_King Senior Member

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    A comfortable temperature is different for each person. If I have my wife or other passengers with me I keep the climate setting on AUTO 70F. I don't change 70F temperature settings throughout the year, but this winter I am using more manual controls when I am alone in the car. But in wintertime, if the cabin temp actually gets to 70F, it would be so uncomfortable for me. Luckily with my manual climate control setting, AUTO OFF, A/C OFF, temp 70F, use manual control to set the fan at 2 and direction of a blow if heat or defogging is needed otherwise turn the system OFF most of the time, the cabin temp almost never gets more than 10-20F above the ambient temp. Although most of the time I try to turn on the HVAC only during the time my car is running the engine in HV mode, the last time I run my entire 18 miles morning commute on EV mode in the cold morning (ambient temp at ~16F) and using minimal heat-pump heating, the cabin temperature never exceeded 32F, but I was quite comfortable at that temperature.
     
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  17. Paul.Ivancie

    Paul.Ivancie Member

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    I sold (yeah, right!) my 2006 Prius with 350K miles on it to my son. I have just recently clocked 56K on my 2017 Prius Prime (Advanced, Blue Magnetism), and reluctantly re-tired due to a road hazard non-repairable slow leak at only 50K. (One should never replace just one tire, and as long as the mileage was as high as it was, and winter was just around the corner, I sprang for a full set.)

    I made the mistake of trusting the service supervisor, and allowed them to install their “best tires,” whereupon my mileage went almost instantaneously from 6mi/kWh to 5. Now, in the depths of winter, I am down to 4mi/kWh. My range has been cut from almost 40 mi/chg to 20. Currently, my mileage spreadsheet shows a lifetime average of 138.19 MPG. I keep my interior temp set at 68 in the winter and 74 in the summer. I buy exclusively ethanol-free gasoline on the first of the month, usually 1 gallon or less for the 1,000 to 1,500 (mostly local) miles that I rack up. I only recently experienced unwanted interior windshield fogging (during periods of single-digit and/or negative temperatures), and so have reluctantly activated the fan motor while directing the airflow to the windshield and killing the air conditioning if it should come on. This does has the effect of clearing the windshield... slowly... causing me to hunch down to peer through the clear space creeping up from the bottom of the windscreen.

    I am not sure, but I would suspect that the heat generated by the traction electronics is somehow being used to provide the warming of the air stream when I kill the A/C. Maybe some chat member can shed some expert light on this assumption of mine.

    BTW, If anyone is interested, my aforementioned spreadsheet has my cost of driving currently pegged at 63 cents per mile. This includes all costs, including estimated electric charging utility costs. I am considering buying a ChargePoint® home unit, so I can keep better track of that parameter. My WAG at this expense is about $500 per year, which would account for about 5 cents in the above figure. The total cost, including purchase price (less tax incentives and factory rebate), sales tax, gas and oil, maintenance costs, replacement tires, insurance, and estimated electricity costs, is about $35,000. I never trade my cars in, since I tend to either run them into the ground or donate them to charity, so the above cost is simply divided by my total miles driven. I have only discarded six of the eight cars that I have owned in the past 50 years.

    When my son started driving my 2006 Prius almost full time, it had 290,000 miles on it, and at that time, the cost of ownership per mile was 18 cents. (However, in that spreadsheet, I neglected to add in the cost of insurance, which probably would add about 3 cents per mile.) He has since added almost 80,000 miles, since his daily work commute approaches 90 miles round trip.
     
    #17 Paul.Ivancie, Feb 19, 2020
    Last edited: Feb 19, 2020
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  18. m8547

    m8547 Active Member

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    The heat pump runs to provide heat whether or not the AC light is on. I'm not sure if heat from the electronics is used to heat the cabin, but I suspect it's not.
    • There's a separate coolant circuit for the inverter, and it seems unlikely that they would go through the trouble of adding a second heater core for it, when it rarely puts out enough heat to be useful.
    • The electric motors are cooled by transmission fluid, which probably circulates through the radiator like every other automatic transmission car, but probably does little to warm up the engine coolant and heater core if the engine isn't running.
    • The battery lives in the trunk. It is cooled by cabin air, so in theory it could warm the cabin a little. It doesn't seem to make enough heat to be noticeable in the winter. Sometimes in the summer the area on the floor in the center of the back row gets slightly warm.
     
  19. Salamander_King

    Salamander_King Senior Member

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    As commented, the heat pump can heat the cabin without A/C switch on. I initially thought the A/C switch was for the electric compressor, so the switch needs to be on in order to cool (air conditioner), heat (heat pump), and dehumidify, but turned out the switch was ONLY for cooling (air conditioner). Both heat pump and dehumidifier can run the compressor without the A/C switch is ON.
     
  20. Tickwood

    Tickwood Member

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    The 12 battery is under the hood of my 2020. did earlier models have it in the trunk?
     
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