Inquiring Minds Questions

Discussion in 'Gen 3 Prius Technical Discussion' started by Harrinj, Nov 17, 2009.

  1. Harrinj

    Harrinj Junior Member

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    Hi folks,

    I have a 2010 Phase V Nav Prius and cursiosity has gotten the best of me, so a few questions.

    1) When viewing the one-minute mileage chart on the dash, does it actually keep track of second-by-second mileage and display the true average over the entire minute, or just display the current mileage at the moment the dash is updated?

    2) Does using the Eco button actually increase the average mileage rate? It seems to me the button just prevents the engine from accelerating beyond the engine's available torque ability? (i.e. the car can only go so fast by pushing the gas pedal halfway; pushing it farther only wastes gas; the car can't go any faster).

    3) Does anyone actually use the EV button when driving? I've had the car for six weeks now and today's the first time i tried using it. I commute 60 miles each way to/from D.C. and sit in quite a bit of traffic. I drove for nearly an hour today in stop and go traffic (below 25 MPH) and using EV, saw a dramatic increase in my average MPG numbers. Can this harm the car in any way. I assume the button's are available for this purpose?

    Thanks for any responses...

    J.D.
     
  2. Bobsprius

    Bobsprius BobPrius

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    Since I drive a V I guess I will take a stab at your questions:

    1) I believe this to be cummulative over the minute. I don't know if it's second snapshots or one minute in all honesty sorry....It may be. Bob Wilson know's this vehicle and am sure he will have a good idea..

    2) I beleive the ECO buttons adjusts the throttle position so that you are more Economic with the Accelerator pedal basically....But if you push it harder you will gain much more power if needed. I tend to use PWR when entering a busy road from a off ramp and find it has more "Guts" but that's my opinion.

    3) Using EV should be for shorter distances because as the Hybrid Battery charge is depleted, the ICE (engine) will come on more often to charge the Batteries. There are many thoughts on this functionality but if you have seen a DRAMATIC improvement in mileage and can share some stats, the group would be interested to hear your results.
    It will not really harm the Battery from what I know of using EV though....
     
  3. chrisj428

    chrisj428 Active Member

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    JD,

    Let me just chime in on what Bob's already stated.

    1) The minute-by-minute economy display is average over the duration of the minute and not just a snapshot. I was able to verify this while in construction traffic. After many minutes of not moving, I was able to creep forward a foot. When the display updated a little later, it showed a full bar surrounded by a bunch of blanks from not moving for a while.

    2) The ECO button will adjust throttle responsiveness for the first 50% of pedal application and also changes the logic for the climate control modulation. I'm not sure, specifically, what changes with the climate control -- I've read that a/c compressor functioning is dialed down and I have heard a change in the noise the system makes if I engage ECO whilst not moving (so no other ambient noises around).

    3) I would only use EV for things like parking garages and lots. Some had mentioned previously that, in reality, EV had a detrimental effect on overall fuel economy, unless one had a plan in place to "regen" the energy used, such as driving back down the ramps in a parking garage. Otherwise, the ICE will run more to top off the traction battery.
     
  4. MJFrog

    MJFrog Active Member

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    3) Let me throw my 2 cents in here too. Even though I have a Gen II, the general idea is the same for Gen II and III. Under MOST circumstances, using EV mode will waste energy in the long run. This is because energy in the battery mainly comes from the gas engine and there are conversion inefficiencies throughout the whole process.

    There are some exceptions (there always are...). If you're coming to a downhill run for a good distance (varies, but long enough to recoup battery via regen), then using some of the battery will allow room to 'top off' through regen while going downhill.

    If you're stuck in the middle of stop and go traffic...moving say...20 to 50 feet at a time (similar to a parking lot;)) then EV would be better than gas. The farther you go in one move, the less advantage over using gas...accelerating quickly in EV is very wasteful.

    If you have an add-on battery pack (PHEV), then you DO want to use EV as much as possible within the limits of the add-on pack. Some packs (e.g. Enginer.us) are designed to assist the Prius pack while 'at speed', while others (e.g. Hymotion) allow for limited full EV mode.

    hope this helps
     
  5. David Beale

    David Beale Senior Member

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    Further comments from a GII guy.

    You don't -have- to use the EV switch to use EV mode. Gentle throttle application while crawling in traffic (engine warm, battery charge good) will result in the same effect.

    The switch allows you to shift a bit of the Prius fuel efficiency logic. The Prius is well designed, but its' one big shortfall is that it can't -anticipate-. -YOU- may know you are going to be going downhill soon, so much that the battery will end up "fully charged" (about 80%), so you should use up some battery energy to make room for that charge, and save fuel while doing so. The Prius doesn't and can't know this. -YOU- may know you will be waiting in traffic for 10 min. The Prius can't know this.

    So you "take steps". The EV switch gives you one more option to do so. Using it knowing you will not recover that electrical energy from potential energy conversion (going down a hill) means you are actually "wasting" some energy. As stated above, if you have to replace the battery charge using gasoline (engine must run) the efficiency is thought to be about 50% (ignoring the energy wasted running the engine), whereas if you used the gasoline engine to push the car it would be 100% (again, ignoring the energy wasted in the ICE, which is around 35% efficient while running). In other words, running the engine wastes about 65% of the energy in the gasoline, but running the engine to only recharge the battery, then using the battery energy to push the car wastes a further 50% of the 35% you got running the engine in the first place. (that was long winded, but I hope you get the idea). ;)

    The eco/normal/power selections mostly just shift the throttle response. They don't lower or raise the power the car will make. In other words, no throttle will be just as powerful and full throttle will be just as powerful, but half throttle will be noticeably different. This perceptional change has been used by car makers a lot to make customers think their car is more powerful than it actually is. Examples include the Ford Taurus, which was one the first to do it in the "modern era".
     
  6. 3PriusMike

    3PriusMike Prius owner since 2000, Tesla M3 2018

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    No. The button is a "hint" and when the computer decides that engine is too cold, or the battery SOC is too low or you are going too fast you get dumped out of EV mode.

    I'm not sure why so many are so adamant about using EV mode is something that lowers mpg. But at the same time, if they are driving at 35 or 40 mph and the ICE is off then that is OK. It's the same thing folks. (almost) IMO, the truth is that it doesn't make much of a difference either way by using the EV mode button, since you have to be going slow, not accelerating much, etc.

    There are some logical times when using the EV mode is most advantageous. Moving your car in a parking lot, moving in in/out of the garage to wash it. This makes a lot of sense because you won't ever start the ICE at all. Another time is a the end of a trip and you are ~1/4 mile from the end of the trip. Running the ICE isn't needed to keep the engine or Catalytic converter hot -- you don't need this "waste" heat any more. Same thing if you are on a multi-hour trip and are making a quick stop for gas, food etc. since the car will stay warm in any case.

    Does EV mode make sense in the middle of a trip? Probably no more (but a bit less) than throttling back and driving with the computer deciding to be in EV mode without the button being pressed.

    3PriusMike
     
  7. nparker13

    nparker13 Member

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    Sometimes I'll use it if I want to start the car and program nav system before moving. I'll hit EV immediately after starting to prevent the ICE warmup while I'm sitting idle.
     
  8. rod

    rod New Member

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    What am I missing here? You say that you use it (EV mode) in the morning or in a parking lot. Yet when I push the button for EV the ICE still starts and runs until it warms up, by then I'm on the highway. Also with the weather in the 50s now the ICE runs whenever I turn on the heater, weather moving or not. It hardly ever turns off, reguardless of speed.
     
  9. going red baby!

    going red baby! still a n00b

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    Curious if you just push the PWR button while in motion coming up to a ramp? I just picked up my car last night and didn't get that far in the manual while getting my windows tinted today. I do have a hill up to my house and so I pressed the PWR button once I was at the bottom of it and it helped me zip up the hill and I turned it off once I hit the top. Is this the proper way to use it?
     
  10. F8L

    F8L Protecting Habitat & AG Lands

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    It depends on your opinion. Do you want to press the pedal down 1/4 of the way to the floor to get up the hill or half way to the floor to get up the hill? It doesn't matter to the car as the power output is exactly the same. Only the throttle position and your interpretation of the cars power output has changed. David explained it above:

     
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  11. David Beale

    David Beale Senior Member

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    Just to provide a little more explanation.

    Because the three modes (eco, normal, power) provide the same minimum/maximum power, you may be asking "what are they for, then?".

    Well, just try to modulate the throttle on a GII to achieve "warp stealth" (engine running with no fuel injected, while traveling faster than about 42 MPH). It's -really- difficult. Try it in a GIII in "normal" mode. Still hard. Now try it in "eco" mode. Much easier! You get more throttle pedal movement per "control input" to the car.

    So why do you need a "power" mode? Well, sometimes you may want to throw mileage to the wind and zip about. It's easier in "Power" mode than the other two modes, requiring less throttle pedal movement.
     
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