EV Mode: How Far Do You Get?

Discussion in 'Gen 4 Prius Fuel Economy' started by Coast Cruiser, Jun 1, 2016.

  1. CR94

    CR94 Senior Member

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    It doesn't make sense, does it?! The reason has something to do with meeting US (or California) emission regulations, we've been told in earlier threads. Exactly how requiring starting the engine to move the car a very short distance on a cold day minimizes air pollution is beyond my comprehension. If I recall correctly, engine temperature must be at least 20°C in the US for EV mode to be allowed. The threshold is considerably lower elsewhere (maybe 0°C?). That's for 3rd generation Prii; I don't know whether the 4th behaves similarly.
     
  2. Maxwell61

    Maxwell61 Active Member

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    Some our EV gen4 member has noted the following: under 15° outside temp, the warming up cycle starts after few secs from ignition as gen3; over 15°, it starts only if you push over the half of the ECO bar in the powermeter. No precise indications if the max EV speed with the cold engine is reduced as gen3.

    The Yaris HSD (same engine of the Prius C), shows the latter feature indipendently from the temp
     
  3. Isaac Zachary

    Isaac Zachary Junior Member

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    Although not a Prius, in my Hybrid Avalon I've managed to go several miles on pure EV power. But this is due to the hilly nature of where I live, so you could say on pure EV and gravity power. There are a few descents that allow for the car to turn off the engine at speeds below 47mph for several miles, perhaps regenerating or powering a bit or both. I've also found that if I get to the top of a hill and shift into neutral (not recommended) after having managed to get the car to shut off the engine the car will keep the engine shut off even if it speeds up past 47mph. (The highest speed I've gone like this was 65mph).

    The last time I tried on a couple hills it I got over 43mpg in a 65 mile trip in spite of a 2,000ft total climb.
     
    #23 Isaac Zachary, Aug 24, 2018
    Last edited: Aug 24, 2018
  4. RCO

    RCO Senior Member

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    You won't get any regen if you coast in neutral!
     
    #24 RCO, Sep 1, 2018
    Last edited: Sep 1, 2018
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  5. alanclarkeau

    alanclarkeau Senior Member

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    Yes, definitely - and the ICE can't possibly come on if you're in "N" (UNLESS the A/C says there isn't enough left in the HYBRID Battery, or you've got the heat turned up and it turns it on for that).

    If the road were steep and straight enough, and you didn't brake, the car would continue to accelerate till terminal velocity - like VERY fast.

    And - if you did brake, it would only use the old-fashioned Disk Brakes.
     
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  6. Isaac Zachary

    Isaac Zachary Junior Member

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    In a perfect world regen braking would be 100% efficient. In reality it isn't. Some heat still gets produced as a byproduct of the process. So the alternative (if you don't have anyone behind you) is to coast in neutral, or better yet, to hold your foot to where you're right at neutral and let the car slow down on it's own. This can be more efficient than regen braking. Say you have a stop sign X amount of miles away. The most efficient way to stop is to go into neutral (or hold pedal to where there's no regen nor any power) and start coasting far enough away that by the time you reach the stop sign your speed has diminished to the point that you are almost stopped.

    Of course in reality that isn't always possible, and so regen braking is better than friction braking and does the job just as near as well. But if the circumstances allow for it there are times that coasting can be more efficient than regen braking.

    True, true, true and true. But there are also downhill areas that aren't that steep. One place in particular that I regularly drive on starts out at the top of the hill at 40mph. I sometimes creep down to 35 or 30mph if nobody is behind me. The speed limit immediately changes to 65mph. By coasting in neutral I can reach 60-65mph top speed. Then it goes up hill a bit and in neutral I slow down to about 40mph again before the slope is downhill again. Then I can stay in neutral quite a while until close to the bottom of the hill where I have to start braking to keep from going over the speed limit, which I do with regen. And I as I reach the bottom my battery is just getting full. Mind you that the whole thing is about 6 miles long and I can do the whole thing without the gasoline engine running at all.

    Of course if I have any traffic behind me it's different. When I get to the 65mph area I almost have to use my accelerator to make those behind me happy. But right after that I have to start regen braking to keep from going over the speed limit. Then I'm going up hill at 65 mph having to use the gasoline engine to keep my speed up. Then I'm going downhill again and have to regen. But by the time I get near the bottom my battery is now full from starting out at the top at full speed of 65mph and now I have to engine brake or friction brake. So in the end I use more fuel staying in gear and trying to follow the speed limit than just going for a roller-coaster ride.

    Again, I do not recommend coasting in Neural because it is unsafe. If you suddenly need to brake all you'll have is your friction brakes. In reality, there isn't much difference between coasting in neutral and just keeping the pedal right where it isn't regen braking nor making any power except the engine comes on and idles at speeds over 47mph and turns off at speeds under 47mph.
     
  7. alanclarkeau

    alanclarkeau Senior Member

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    I see what you're doing - I've had that in a few places in the past, but nowhere I go regularly now. I was driving a 6sp Manual Diesel FOCUS at the time - and a couple of times, tried resetting the l/100km at the start, using either minimal throttle or "N". Yes, it did use more fuel in gear - but was surprisingly low. It'd be interesting if you reset at the top under both scenarios (could use TRIP B if you're not using it for anything else).
     
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  8. RCO

    RCO Senior Member

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    I hear you, but agree with Alan as well. In using my model as a generalisation you use your unique example of a better method which on area known to you but not be available to all and sundry.
     
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  9. Analogkid1958

    Analogkid1958 Member

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    The owner's manual describes pretty well how you can drive the Prius to maximize use of the hybrid battery while driving.

    Pressing the "EV" button is basically for parking lots and traffic jams, but while cruising you can modulate the throttle to turn off the engine and run on the hybrid battery. Search here for "pulse and glide."

    But this depends on the battery's charge and load on the car (this won't work going up hill) and whether the engine needs to run to warm up.

    It's a fun game to play once you get used to it.

    Good luck!
     
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