Hybrid vs EV mode

Discussion in 'Prime Technical Discussion' started by Pizza Driver, Oct 17, 2016.

  1. Pizza Driver

    Pizza Driver Active Member

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    I have seen a flow from the engine to the motor and then from the motor to both the wheels and battery at the same time. Perhaps there is some lag in the display involved. I also seem to remember seeing the engine going to the motor and then to the wheels without the battery being involved. I am not sure of this since I generally do not use the energy monitor when driving. I use the eco meter i.e. "charge, EV, eco, power" display.
     
  2. JamesBurke

    JamesBurke Senior Member

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    For mixed highway and city driving the question is the amount of fuel used by charge mode per EV mile generated under various MPH, topographies, and weather conditions vs. the amount of fuel used by hybrid mode in stop and go driving conditions over an equivalent mileage. What ratios of fuel use will be acceptable or desirable under these various conditions.
    Was this statement easy to understand? Looking for ways to explain this to those with no experience with hybrids or plug-ins.
     
  3. Lee Jay

    Lee Jay Senior Member

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    The engineer said it will take between 1/4 and 1/3 of a gallon of gas to charge the battery from Ev-empty to 80% charged, presumably depending on conditions. That makes sense.
     
  4. Tideland Prius

    Tideland Prius Moderator of the North
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    I believe the wife has a plug-in car in the garage (Ford Fusion Energi)
     
  5. Jan Treur

    Jan Treur Active Member

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    If that's not a BEV, why not share by taking the garage every other day for each?
     
  6. TonyPSchaefer

    TonyPSchaefer Your Friendly Moderator
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    Like Tideland said, my wife gets the 1-car garage. In the summer, during nice weather, we might take turns parking in the garage. When the weather is foul and certainly during the Winter, I am not going to make her park outside.
     
  7. GT4Prius

    GT4Prius Active Member

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    Just noticed that word "available" before Predictive Efficient Drive! A slightly sneaky way of saying that it won't be on all models.

    Disappointing!

    Anyone any info as to which models will include it?

    Posted via the PriusChat mobile app.
     
  8. giora

    giora Senior Member

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    Interesting, let's do some math:
    Assuming 44 MPG with charge compared to 54 without.
    1/4 to 1/3 of a gallon - lets take 0.29 as middle point. then:
    X/44=X/54+0.29. Solving gives X=68.9 miles.
    So, for the assumptions above it will take about 66-70 miles to get the battery from hybrid level to 80% full (80% of Toyota full or about 20 miles EV).
     
    #48 giora, Oct 20, 2016
    Last edited: Oct 20, 2016
  9. Lee Jay

    Lee Jay Senior Member

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    That's twice as fast as a 240V charge.
     
  10. giora

    giora Senior Member

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    Yes, maybe the 80% limit is due to the higher rate?
     
  11. Lee Jay

    Lee Jay Senior Member

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    Or due to saving a little space for regeneration.
     
  12. Prius Maximus

    Prius Maximus Senior Member

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    Premium or Advanced only, not the Plus.
     
  13. Trollbait

    Trollbait It's a D&D thing

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    But not as efficient.

    Likely this. The pack is still only air cooled, and fast charging is heating it up. Then the slower rate to fully charge to pack might not have been too inefficient for Toyota engineers.
     
  14. giora

    giora Senior Member

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    I would not rule out some room for regeneration. Maybe both?
     
  15. Jan Treur

    Jan Treur Active Member

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    Some more maths:
    The 0.29 gallon times 54 could have given you 15.66 miles when you would have used it for driving. What you get via charging the battery is about 20 miles EV. So, is there some mistake here? Or is this way of operation giving you 25% for free?
     
  16. Trollbait

    Trollbait It's a D&D thing

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    I would think the buffer of battery capacity left when the car is fully charged is enough to handle any extra from regen braking. Leaving the avoidance of battery overheating and worse efficiency hits the most likely reasons.

    From my rough calculated speculation, going 20 miles on Charge mode EV uses a little bit more gas than going the same distance in Hybrid mode. There are variables that can't accounted for now. Such as how Charge mode might effect Hybrid mode efficiency beyond the fuel burnt for charging, or how efficiently EV miles are used, like avoiding warm up on multiple short trips.
     
  17. giora

    giora Senior Member

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    But there is no buffer, that is the meaning of 'fully charged' it is the highest level permitted by the system.
     
  18. Trollbait

    Trollbait It's a D&D thing

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    And the system's 'fully charged' is below that of the cells' full capacity.

    I think you had calculated that the portion of the battery used for EV was 6kWh or a little higher. The pack is 8.8kWh. Subtract out 1.5kWh for hybrid operation, and there is still nearly 2kWh of capacity. Some of that capacity will be charged, because I can't think of any battery chemistry in which being fully discharged is a good thing for longevity, and it won't be fully charged for the same reason. For Li-ion, it is best to keep them at 80% charge.

    So there is empty space for some regen braking. Otherwise, a fully charged Prime would be incapable of regen braking at the very beginning of a trip.

    This raises another reason for only having Charge mode go to 80% SOC. There might be a maximum amount of battery charge in which the system won't allow Hybrid mode to be entered. European spec i3 REx have to drop down to 75% charge before the range extender can be turned on. In hybrid mode, energy can be going from MG1 to the battery at a steady rate. Having some of the EV charge used before entering hybrid mode can eliminate this charging from overstressing the battery's overhead capacity.
     
  19. giora

    giora Senior Member

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    You are confronting Toyota engineer (who said that 1/4 to 1/3 of a gallon will be used to generate 20 miles of EV) not me.
    I feel that something is wrong with your logic but cannot pin-point it immediately. The 0.29 gallon was spent on top of what needed for moving the car, it is marginal load, if the car (charge off) could move further to the said distance on marginal load only it would do this further distance at an efficiency much higher than 54 MPG.

    EDIT: added
    Let's look at it from another angle:
    0.29 gal worth 0.29x33.7=9.77kWh.
    The usable capacity (usable for EV) of the pack is ~5.72kWh (my assumption of 65% of total), 80% of it is 4.6kWh.
    Efficiency of this forced charging is then 4.6/9.77 or 47%.

    If 1/3 gal is used then it's efficiency is 41%
    If 1/4 gal then 54%.
     
    #59 giora, Oct 20, 2016
    Last edited: Oct 20, 2016
  20. giora

    giora Senior Member

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