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Power mode is by far the best mode to be on to get the highest MPG?

Discussion in 'Gen 4 Prius Fuel Economy' started by TheChosenOne, Feb 8, 2016.

  1. TheChosenOne

    TheChosenOne Member

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    I googled hypermiling last night and came across this site that talked about the older Prius. The site gave me info I never knew about and the info will help me get better MPG from my Prius. I already knew about not accelerating fast, and coasting but with the new stuff I learned, I looked at the energy monitor thing on my Prius and when I'm on ECO mode, if I accelerate to keep up with traffic in 25-35MPH zone but still staying in the ECO range in the accelerator guide, it only uses the engine to power the tires. And when I tried to go at a steady pace and make sure the energy monitor shows the hybrid battery powering the tire which would give me better MPG, I notice I don't go at at the same speed but instead I go a little slower so I would have to accelerate faster which would use the engine and that means less MPG.


    On Power mode I step on the pedal lightly and it accelerates faster than on ECO but it don't use the engine and the energy monitor shows the hybrid battery powering up the tire and the MPG gauge goes up. Is being on Power mode all the time the best way to go? Also before knew new info about hypermiling and looking at the energy monitor to get the best MPG on my car, I just kept I don't accelerate fast and I coasted every chance I got but I notice the MPG indicator would have it between the low 20s to 40s after driving 5-10 miles then go up to the 50s and 60s after driving 15+ miles. Why is that? Is it because the hybrid battery isn't close to being full and when it is close to being full, it powers the tires even when accelerating higher than the optimum speed?
     
  2. bisco

    bisco cookie crumbler

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    pulse and glide:
    you want to accelerate using the engine. not sure if the 16 still has the hsi screen? if so, keep the bar a little to the right of the eco line, but in any case, keep up with the car in front of you as necessary.

    stop accelerating when you are somewhere above the speed limit, and then glide. gliding means your best effort to keep from powering the wheels, but not to regen either. usually this means just a little bit of battery because pure glide is difficult to achieve,

    when you slow down to somewhere below the speed limit, rinse and repeat. keep in mind, this is not recommended with traffic behind you.

    i don't think the mode matters, although eco will save you some gas from reduced heat and a/c.
     
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  3. Trollbait

    Trollbait It's a D&D thing

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    The Prius doesn't have a plug, so all its energy will have originated as gasoline.

    There are losses involved in charging and discharging the battery. So Eco mode uses the engine for acceleration to avoid those losses. Power mode uses the battery for more power, or goes to it quicker than Eco, while accelerating. This can lead to the MPG going up at that time, but battery will have to be charged back up at some point. Even if from regen braking, the losses of getting the energy out of the battery, and putting it back in mean you'll have to use more energy to get the battery back up to where it was before you took it out.

    It is because of the warm up cycle. The newer generations can warm up the engine pretty quick, but there is also the catalytic converter to warm up. So the car uses the ICE more during those first few miles until everything gets to optimum temperature, and this is why you should try to plan to do multiple errands on a single trip with any car.
     
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  4. eric1234

    eric1234 Active Member

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    Where does this information come from?

    This is not how I have read that Eco/Normal/Power mode operate. I believe that the difference between the three modes is accelerator pedal mapping (the Prius is drive-by-wire) and reduced fan speed (and possibly compressor speed, too)
     
  5. bisco

    bisco cookie crumbler

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  6. TheChosenOne

    TheChosenOne Member

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    Wait so it's possible to not have the engine or battery power the wheels and not have the wheels regenerate energy back to the battery but still get the car moving? Lets say we go 5 MPH over the speed limit in a 25 MPH zone, how long can we stay at or above the speed limit without any activity in the energy monitor before we need to accelerate again to go 5 MPH over speed limit?
     
  7. bisco

    bisco cookie crumbler

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    depends on a few factors like grade and wind and friction. but it's usually not too long. on a flat 30mph road in good weather, with not much traffic, i typically accelerate to around 35, keeping the hsi bar just to the right of the eco line, then try to glide, yes it's nearly impossible, so i keep the bar just to the right of regen, which uses a minute amount of electricity. some people pop it into neutral, which is easier, but controversial.
     
    #7 bisco, Feb 9, 2016
    Last edited: Feb 9, 2016
  8. Trollbait

    Trollbait It's a D&D thing

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    Right on the mapping, but I was referring to the info in the OP, "I looked at the energy monitor thing on my Prius and when I'm on ECO mode, if I accelerate to keep up with traffic in 25-35MPH zone but still staying in the ECO range in the accelerator guide, it only uses the engine to power the tires."

    My gen2 didn't have these fancy shmancy modes, but my reading here is that the Eco pedal map makes it easier to keep the accelerator in this eco range than with power, assuming the power mode bother telling you if you are in it or not.
    Yes, this is possible, and what is actually what a glide is; nitpicky hypermilers can call the time when the simulated engine drag of regen braking a coast.

    How easy it is the glide, and at what speeds it can be done without EV input vary by the generations. Just feather the accelerator until there is no regen happening without power going to the wheels. At higher speeds it might not be possible to get the no power going anywhere on the energy diagram, but you can hit a point where just energy from the battery is used; which some call warp stealth for some reason:unsure:.

    The goal is to simply go as far as possible before having to make the engine turn back on. Putting the car in neutral will do the same thing, but, depending on speed, the car might run the ICE in idle while in neutral. This is where things like a Scangauge become useful, because they can show more of what is going on in the car.

    How far a glide goes depends on many factors; tires and their wear, the road surface, incline, etc. 'Aggressive' pulse and glide will have a larger speed delta than 5mph, but without going there I was seeing 55+mpg on my commute in the 2005.
     
  9. eric1234

    eric1234 Active Member

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    So, these were the words I keyed off of, and (in my interpretation) it is not at all like accelerator pedal mapping.

    Accelerator pedal mapping defines how much motive power is requested from the Hybrid System at a given amount of pedal displacement.

    How the Hybrid System chooses to fulfill the request (via the battery or engine) remains unchanged.

    Sorry to be overly semantic, but that's what happens when you cross an engineer with a lawyer... ;-)
     
  10. rdgrimes

    rdgrimes Senior Member

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    Partly accurate. The system also factors how far and how quickly you press the throttle. So a change in throttle mapping can indeed effect how much electric vs ICE power is called for from a given pedal motion. The result may be that a person perceives a difference in one thing that's actually something else. IOW there are too many things going on at once to accurately isolate one factor.
     
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  11. Trollbait

    Trollbait It's a D&D thing

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    Again, I was responding to the OP, "On Power mode I step on the pedal lightly and it accelerates faster than on ECO but it don't use the engine and the energy monitor shows the hybrid battery powering up the tire and the MPG gauge goes up," and framed my response within their phrasing. So your complain is really with their terminology. ;)

    For effective pulse and glide, you want the pulse to be under medium hard acceleration. At about 70% load on a straight ICE car. That doesn't yield the best MPG while accelerating, but it is at that point most engines are most efficiently converting the chemical energy of the fuel into mechanical energy. The overall MPG for the trip with be high though, because the car will spend more time gliding with ICE off than accelerating.

    Which mode is best; eco, normal, or power, does not matter. They just change the car's response to accelerator pedal inputs, but not minimum or maximum power outputs. You can accelerate just as quickly in eco mode as in power; you just have the push the pedal farther. Eco mode might be best for practicing feathering the car into a glide, but once you are experienced doing so, you shouldn't have a problem getting the same results in the other modes.
     
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  12. eric1234

    eric1234 Active Member

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    Yes, it is. I'm not at all sure what that means, as I re-read it multiple times.

    Yes, that is exactly what I've come to learn and understand. :)
     
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  13. Kramah313

    Kramah313 Active Member

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    One thing I have noticed with my scangauge is that in power mode, there is a quick and strong burst of current from the traction battery when you hit the pedal that doesn't seem to be there in the other modes. I have seen this current draw be up to 100 amps if I really step on it, but it usually only lasts about a second or two. I believe this is what makes power mode feel faster as it gives instant response. After that it seems to be the same as just pressing the pedal harder in Eco or normal mode.

    I switched to power mode as my usual mode because when I tried it I got better mpg, and it makes the pedal feel more like our Honda odyssey's. Before, when I was always in normal mode, I would always hit the pedal too hard on the odyssey and make it jump. Sometimes I use Eco mode in a residential area or parking lot so I don't have to be so careful with the pedal while keeping my speed and acceleration low.
     
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  14. Edwin Palmer

    Edwin Palmer New Member

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    When I bought my Gen 3 last year , the salesman made me try Power mode. I thought it was stupid , because you can't start smoothly and control throttle accurately. That's what I hated about my 08 Civic ( and most modern cars). The non-linear throttle response fools many people into thinking their car is fast , but it doesn't help when you're hypermiling.
     
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  15. Kramah313

    Kramah313 Active Member

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    Yeah most cars' pedals are front loaded. If I don't use power mode in the Prius to make it feel that way too then I wind up jerking everyone back and forth trying to stomp the gas pedal in the van haha.

    I think mpg is better for me in PWR because I don't accelerate hard enough in normal, which is a result of being used to other cars' front loaded pedals
     
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  16. akhare

    akhare Member

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    IME, using power mode on steep uphill grades (4% or more) works best and seems to keep in the gauge below the red zone vis-a-vis attempting the same in Eco (especially at higher speeds). On very steep grades (6% or more), I haven't been able to better 45mpg while maintaining a fairly good speed (50 mph). The trick here seems to be shifting back to Eco on the flats and downhills (naturally), though it probably won't make much of the difference on the latter.

    Also, another tip is to use the EV mode when stopped at lights -- the acceleration will likely disengage it fairly soon, but it does seem to help a little bit (54.1 mpg on the first fill and trending towards 60 mpg here).
     
  17. Mendel Leisk

    Mendel Leisk Senior Member

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    Then maybe a good idea to not use PWR mode, to protect the inverter more? Might be nothing, but hey.
     
  18. Kramah313

    Kramah313 Active Member

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    It would be interesting to hear if anyone has had a failure of the inverter early that uses a lot of power mode (I certainly will post of I ever do, I use power mode about 90% of the time). Personally I would be surprised as the current burst is very short. I also have not noticed any significant temp increase in inverter coolant temp from it.
     
  19. bisco

    bisco cookie crumbler

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    i had the exact same experience with my idiot salesman.
     
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  20. Mahagodage Amal

    Mahagodage Amal Junior Member

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    I am using power mode regularly.
    It gives more mpg than other modes.