Do Hybrid have different hypermilling tips?

Discussion in 'Fuel Economy' started by Hypochondriac, Jul 7, 2018.

  1. Hypochondriac

    Hypochondriac Member

    Is hypermilling in a hybrid different than a regular car? For example when going downhill in an automatic, you want to avoid braking and just use engine braking so your car is in deceleration fuel cut off, but hybrids have regenerative braking, so does that mean I should brake when going downhill? Same issue with coasting, on a automatic you save mpg by coasting and avoid braking, but is that also the case with hybrids?
     
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  2. RedylC94

    RedylC94 Well-Known Member

    What sort of hybrid? In general, no, don't brake unless you need to slow down anyway to be safe or legal. Freewheeling is usually better, when practical. Depends on the details, including how steep the hill is, what model, etc.
     
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  3. Hypochondriac

    Hypochondriac Member

    Camry hybrid 2018. Does the car regen the battery if you freewheel?
     
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  4. EdwinTheMagnificent

    EdwinTheMagnificent Legend In His Mind

    In a Toyota hybrid , there is a "sweet spot" where you are right in between making electricity and using electricity.
    THAT is the point where you want to glide at. If you get into regen , you shorten your glide. If you dip into
    the battery to extend your glide ( it's tempting, lol ) , you will have to burn more fuel to replace that electricity.
     
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  5. Hypochondriac

    Hypochondriac Member

    How do you find this spot? Will you see it on the display or something?
     
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  6. thunderstruck

    thunderstruck Super Moderator

    If you see you will need to apply brakes (red light ahead, slow traffic, whatever) try to get on brake as soon as possible. That way you maximize your regen. One question I don't think has ever been answered is if you engage mechanical brakes on Toyota does it still regen. My car is extremely efficient when I run on battery so in city driving I try to keep engine use to a minimum. I don't think TCH offers the same level of feedback to allow you to figure out what driving techniques will help you wring out every possible mile, although I may be wrong about that.
    [​IMG]
     
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  7. EdwinTheMagnificent

    EdwinTheMagnificent Legend In His Mind

    I can tell you how it works in my 2015 Prius Two. Using the Display button on steering wheel , toggle screens until you get to Hybrid System Indicator (HSI). This gives you a lot of useful info and I have it on all the time. It shows traction battery state of charge (SOC) , whether or not the engine is running , if you are accelerating in an efficient manner , average MPG (trip or tank ). At the far left of this screen , you will see the letters "CHG" When the indicator is in this zone , you are regenerating (creating electricity). The "sweet spot" is just between CHG and the beginning of ECO. If you press a little further on the gas , you are using battery.

    This is relatively advanced stuff. I don't know where you are in your journey , so I hope this doesn't offend you. But the most critical part of hypermiling is to determine when to pulse , when to glide , and when to Drive With Load ( DWL). Some people refuse to use Pulse and Glide ( P&G). It took me a while to embrace it. But it's the best way to achieve big numbers ( or small , if you're metric). Is there enough room in front of you to begin a glide ? If not , you are following the car in front of you too closely. YOU control the interval in front of you. Use this fact to create a buffer for safety , gliding , and just less stressful driving.

    But what do I know ? I think Wayne Gerdes has some YouTube videos that explain this a lot better than I can.
     
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  8. RedylC94

    RedylC94 Well-Known Member

    No, because physics says we can't create energy from nothing. By "freewheeling," I meant the same condition Edwin is calling a "sweet spot." That is, neither using electrical energy from the battery to turn the wheels, nor using the energy from the wheels to return energy to the battery. Pure coasting ...

    You must be new at this?
     
  9. Hypochondriac

    Hypochondriac Member

    Relatively new. I just figured with a hybrid you would want to brake more to charge the battery that way you save gas because the engine isn't charging the car.

    What about hybrid modes? Should I always be in evo mode since that uses the battery whenever possible or eco mode?
     
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  10. RedylC94

    RedylC94 Well-Known Member

    Unnecessary braking is usually bad, even with your hybrid, because you'll have to use energy from the engine or battery to make up the energy squandered in braking. With a hybrid, you get some of it back, but not all.

    What does your "evo" mode do? I know more about "EV" mode, which is occasionally useful to avoid starting the engine to move the car a very short distance, but otherwise typically counterproductive for fuel economy---and not great for the battery.
     
  11. Hypochondriac

    Hypochondriac Member

    Its the same as EV mode. Why is it counter productive for fuel economy? Doesn't recharging the battery use less fuel then using using fuel to move?
     
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  12. PaleMelanesian

    PaleMelanesian Beat the System Staff Member

    Where does the energy come from, to charge the battery? It comes from the car's momentum. THAT came from burning gas two minutes ago. The battery charge comes from the gas, just with several steps in between, each of which loses a little bit in the conversion process.

    Chemical energy (fuel) ->
    Kinetic energy (moving car) ->
    electrical energy (regen braking) ->
    chemical energy (stored in the battery) ->
    electrical energy (out of the battery to the electric motors) ->
    kinetic energy (moving the car again)

    Clearly the most efficient method is the first conversion only (chemical to kinetic). The rest recovers energy that would be wasted, but with efficiency loss each step of the way.
     
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  13. Hypochondriac

    Hypochondriac Member

    Think I got it correct me if I'm wrong.

    If you have to come to a stop, you should brake as long as possible, making sure you are using regen braking and not the frictional braking? So for example approaching a red light you know will still be red once you get there, a stop sign or when going downhill and you need to slow down to avoid speeding. In a regular car you would engine brake, but for the hybrid you would regen brake?

    Otherwise if you can maintain legal speed, and get to the light when it will change to green you should coast?
     
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  14. EdwinTheMagnificent

    EdwinTheMagnificent Legend In His Mind

    I think he's got it ! If I know I will have to brake , I start braking gently and immediately , which should not engage
    the mechanical brakes until almost stopped. If traffic allows , and EVERY morning that I work I
    drive between 4:35 and 5:10 AM , I plan a glide to get me to the next signal at about 20 MPH. This way ,
    if it DOES turn red , I've still had some gliding. And yes, this strategy does backfire from time to time, lol.
     
    Last edited: Jul 10, 2018
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  15. PaleMelanesian

    PaleMelanesian Beat the System Staff Member

    20 mph is my usual cutoff as well. If I hit a red and have to stop, it's not a huge loss. If I have to stop from faster than 20 I've made a mistake. Stayed on the gas too long the block prior, or I wasn't watching far enough ahead.
     
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  16. NeilBlanchard

    NeilBlanchard Well-Known Member

    Coasting is the most efficient way to use the kinetic energy you have "invested" in getting the car moving. So, to use a little energy as you can, to cover the distance you need to drive - coasting as much as possible, is the best way to do that.

    You can shift into N (in the Prius at least) by holding the lever in N for about 2s, or by putting it into R (which puts it into neutral right away - and NOT into reverse). This is easier and more consistent for when you know you can coast for a while. Using the "sweet spot" is fine for shorter coasts.

    Regen is much better than friction brakes, but it only regains less than 50% of the energy. So, after you have coasted as much as possible, using regen when you need to slow the car down, is the way to go.

    Hybrids also have a big advantage over ICE cars, in that they don't idle. Plugin hybrids are better still, because they have larger battery packs, and can "absorb" more regen; and can be charged without burning gasoline.
     
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