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which is better?

Discussion in 'Gen 3 Prius Technical Discussion' started by adrianp, Mar 7, 2011.

  1. adrianp

    adrianp New Member

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    just wondering out loud here guys, which is the most efficient using the electric (keeping the to left of the mid point on the HSI), to get the car moving then allowing by a bit more pedal for the ICE to come in at roughly say 15 - 20mph and thus get the cars initial inertia out of the way

    OR

    accelerating more briskly with the ICE firing straight away (but staying within the Eco on the HSI) with the ICE straight into the ICE section on the HSI and then using the power that would of been used in the initial example to keep the car moving


    a good friend was a long distance wagon driver and used to say the worst part for efficiency is getting the 42t initially moving so with that in mind i try to get the dead weight moving on battery first but had read its good to accelerate reasonably quickly to start using the kinetic built up energy for gliding.

    any views?
     
    #1 adrianp, Mar 7, 2011
  2. JimboPalmer

    JimboPalmer Tsar of all the Rushers

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    The less you use the battery, the better the mileage will be. (This will change once the battery can recharge some other way than by burning gasoline)
     
    #2 JimboPalmer, Mar 7, 2011
  3. adrianp

    adrianp New Member

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    hi thanks for the reply, so if i understand you correctly you wouldn't necessarily do as i would in setting off using the battery to slowly 'get going' ?

    thanks
     
    #3 adrianp, Mar 7, 2011
  4. Flaninacupboard

    Flaninacupboard Senior Member

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    The general reccomendation is to "pulse" up to speed and then glide. If you watch the DVD that comes with the prius it does actually tell you this!

    In some situations (for instance, you're not going to go over 10mph, or you're about to go down a hill which won't require the ICE) it is better to use the electric side, in most, it's not. I fidn the car does a pretty good job of selecting power source by you just driving naturally.
     
    #4 Flaninacupboard, Mar 7, 2011
  5. Gurple42

    Gurple42 New Member

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    Is your mileage info based on the Imperial gallon?
     
    #5 Gurple42, Mar 12, 2011
  6. Flaninacupboard

    Flaninacupboard Senior Member

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    Yes, we compare cars based on MPG but buy petrol in litres. Go figure...!
     
    #6 Flaninacupboard, Mar 13, 2011
  7. TonyPSchaefer

    TonyPSchaefer Your Friendly Moderator
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    This question comes up frequently.

    I try to stay away from claiming that I know what's best. But I've seen and heard enough to know that there are others who have had the same questions. Namely, Hypermiling is a sport in Japan. Please refer to this thread by Ken in Japan.
    http://priuschat.com/forums/gen-ii-prius-fuel-economy/8869-1300-miles-2119km-per-tank.html

    How he did it is in post #13 including: "He did the briskly acceleration but no battery assist, no yellow arrow from battery."
    This was a GenII Prius; the GenIII display is different but the theory is the same.
     
    #7 TonyPSchaefer, Mar 13, 2011
  8. giora

    giora Senior Member

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    There is no one definate answer to the question in the original post (starting from standstill) as there are too many variables involved.
    Best advise is in Flaninacupboard post: JUST DRIVE NATURALLY.

    Giora.
     
    #8 giora, Mar 19, 2011
  9. john1701a

    john1701a Prius Guru

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    The most common situation I encounter is the benefit from brisk acceleration. That's when you have a choice, when no one is in front of you.

    Briefly taking advantage of the engine's more efficient operating level (a quick jump to no higher than 3500 RPM) allows you to actually drive a little faster than most traffic.. That provides a moment of battery charging as well as the opportunity for the engine to shut off sooner than with slower acceleration.

    Overall, the outcome of that situation is higher MPG while at the same time not having to baby the car or impair traffic behind you.
    .
     
    #9 john1701a, Mar 19, 2011
  10. donee

    donee New Member

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    Hi adrianp,

    The Prius does not have the motor, battery and interconnects sized to be very efficient in pure EV mode. So, using the electric drive for initial accelleration, which pulls high currents, is not going to be efficient. Start out with an engine acceleration.

    That said, each time the engine has to start, its using a teaspoon of gas that does not go into car movement, and this can add up. So, like if your gliding along, and need to crest a slight hill, its better to do this electrically, then glide down the backside. Rather than start the engine for that brief period.

    When you use the engine, you want to use it for the longest period up to target speed, then try to stay in gliding and EV until you gotta use the engine again for a long period.
     
    #10 donee, Mar 20, 2011
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