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MPG in Hybrid Mode

Discussion in 'Prime Technical Discussion' started by CEJ, May 13, 2019.

  1. Salamander_King

    Salamander_King Senior Member

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    Yeah, I know there are ample amount of threads on this particular topic in the technical section. I read some, and most were way above my comprehension or my interest. :oops:
     
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  2. Raytheeagle

    Raytheeagle Senior Member

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    I’m a degreed engineer and some of it flies by me too:sick:.

    But my interest level is low as well in certain aspects:rolleyes:.

    I figure toyota has smart people working on vehicle design much like I have smart coworkers so I don’t spend too much time figuring out what they already know and built;).

    I’ll spend the saved time here instead(y).
     
  3. CEJ

    CEJ Member

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  4. Salamander_King

    Salamander_King Senior Member

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    On the right of the screen hit "Menue" button, then on-screen touch "Info". On the screen, you will see 5 icons shown below. Touch "Energy" will show you the Energy Monitor on the large screen. You can see the miniature version of the Energy Monitor on the MID too, but you can't use HSI and Energy Monitor on the same MID.

    Screenshot 2019-06-04 at 10.12.54 PM.png

    Screenshot 2019-06-04 at 10.05.47 PM.png

    Screenshot 2019-06-04 at 10.16.59 PM.png
     
    #164 Salamander_King, Jun 4, 2019
    Last edited: Jun 4, 2019
  5. CEJ

    CEJ Member

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    Yep, and this is exactly why I wanted to learn how to do it so I could see both displays at the same time like you did. Thanks. On another subject, I am experimenting again with driving (in HV mode, of course) with SOC at 0%. I am interested to know how the mpg in this case, compares with the mpg when driving in HV mode with SOC not at 0% (which as we have seen can be around 70). So far I haven't gone that far but driving in-town so far I am getting in the 50's but think I got higher than that earlier. Don't recall whether you shared any data in the 0% case, but would be interested if you have any info on this.
     
  6. Salamander_King

    Salamander_King Senior Member

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    My routine commute is 18.4 miles one way for total of ~37 miles daily. I can't charge at work, so I do nightly charge at home. My actual EV range in non-winter season is ~20-35 miles, thus I always run out of EV range before reaching back home and have to drive HV with 0% EV SOC. But my HV daily drive is too short to record on my trip mpg. Only time I drive HV with 0% EV SOC long enough distance to have meaningful mileage records are when I do longer out of town trips or during winter when I don't charge. OR when I intentionally do not charge and run on HV for a full tank to check the HV mileage, like after changing tires.

    In the past ~2 years I have driven my PRIME exclusively on HV with 0% SOC 3 tanks with AS tires, and 8 tanks with winter tires. My data was presented in a graph on my comment #45 MPG in Hybrid Mode | Page 3 | PriusChat.

    With AS tires during non-winter season, I got 61.2, 53.2, 58.4 mpg. During winter with winter tires, the mileage plummeted to 46.5, 48.4, 46.2, 45.5, 44.9, 49.3 mpg. Those are calculated mpg, so 5-7% less than the number displaced on the MID. I keep the record of my Eco Diary into a spreadsheet. Here is a daily record of one HV driving (0% SOC) I did for a full tank during April this year after I changed my tire to OEM AS. You can see that 0 miles/kWh indicates no EV drive. The mpg range 48-66 (excluding a few outliers) for my daily drive from teh Eco Diary and for full tank calculated mpg was 58.4mpg. April in my area is still quite chilly, so the mileage is not the best.

    No HV drive 4-2019.png
     
  7. CEJ

    CEJ Member

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    This is great info, thanks! Are you at all surprised that the mpg in the case of zero SOC is quite a bit less than when in HV mode with nonzero SOC which gives around 70 (or am I missing something)? In the latter case you have been able to restore nearly all of the SOC so basically no net charge was used.
    This is definitely off-thread, but while on my recent trip the cruise control worked fine on the way down. But coming back as I was driving, I couldn't get it to take no matter what I did (on-off etc.). When I powered off at a rest stop, it worked when I started up again--like some kind of reset was needed. I have experienced this with my other non-prime Priuses from time to time. Have you ever had this happen?
     
  8. Salamander_King

    Salamander_King Senior Member

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    My data set for HV driving with SOC remaining is even smaller than the HV driving without SOC. I would think the differences are within margin of error and variation due to driving condition and not dependent on SOC level. It is hard to compare single short trip data as representative of all conditions. If you do enough times to compare HV drive mpg with or without EV SOC remaining, I think the average will be very close if everything else are the same.

    I never had that experience with my PRIME or with previous Gen3 Prius. Then I don't usually use CC. Only time I use it is on a long interstate hwy drive. That happens less than dozen times a year for me.
     
  9. jerrymildred

    jerrymildred Senior Member

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    I've noticed that I seem to get better HV mpg if there are a couple miles left in the battery. But that's just my feel for it. It would take some controlled tests to know one way or the other, and that's impossible in traffic. You'd need a closed track to make a valid test.

    I haven't worked this out yet. I should, though. It seems that, if I cancel the CC with the brake pedal, it doesn't want to resume. But if I cancel it with the CC stalk, it will resume. But I've never really checked it out deliberately to be sure of a pattern.
     
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  10. CEJ

    CEJ Member

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    Interesting observation. That could be what's happening to me because I think I am using the brake to deactivate cruse.
    Very cool and instructive to view the EM on the big screen--really shows what's going on. Surprised to see in some cases energy (charge) flowing from the Electric Motor (or generator/motor, whatever) into the battery when ICE is off. Looks like the energy is coming from the wheels into the motor and then on to the battery? I knew regenerative braking recovers kinetic energy, but didn't know energy from wheels is somehow captured when you are not in braking mode. What's going on?
     
  11. Salamander_King

    Salamander_King Senior Member

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    I might be wrong, but I thought that IS the regenerative braking recovering kinetic energy. Where else would you think the regenerative braking would work?
     
  12. jb in NE

    jb in NE Senior Member

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    When your foot is off the throttle, the car is programmed to regenerate and slow you a bit. Even without your foot on the brake pedal.
     
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  13. CEJ

    CEJ Member

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    Thank you. That must be the answer! I will be interested to see if I can observe this. That is, if the foot is lifted off the throttle, there should be evidence of energy regeneration on the Energy Monitor but not otherwise unless you are actually braking. I don't remember seeing such a correlation but then I wasn't looking for it. And guess this should hold whether ICE is on or not.
     
    #173 CEJ, Jun 5, 2019
    Last edited: Jun 5, 2019
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  14. jerrymildred

    jerrymildred Senior Member

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    To add to @jb in NE's totally true information in #172, Toyota programmed the car to simulate the same kind of deceleration you'd experience in old fashioned cars when you take your foot off the gas. Most of that energy goes to the battery except what's lost in conversion. Some EVs and PHEVs take it a step further and actually work like some electric forklifts where the higher you let the pedal go, the stronger the braking. It's called one foot driving.

    Also note, that with the Prius, there is a sweet spot where the car will coast without driving or regenerating. It essentially acts like neutral. You see it on the HSI when the power bar disappears behind the line separating forward power from charging.
     
  15. Salamander_King

    Salamander_King Senior Member

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    Oh, I see, you were thinking the "regenerative braking" requires the brake pedal engagement. As has been explained by others, the answer is NO. Like Jerry commented, it works like engine brake by downshifting. In fact, if the car has enough momentum, like down hill or after accelerating quickly, even with a slight push on gas pedal still engages in the regenerative braking. Again as Jerry noted, I do most of my commuting drive by one foot drive without using much of brake pedal. With very light traffic and not many stops, I can sometimes drive entire 18 miles without putting a foot on brake pedal. There are some who claims that using B gear during low speed stop and go traffic will allow more regenerative braking. I have not tested this, for I do not drive in stop-and-go type of traffic during my daily commute.
     
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  16. jerrymildred

    jerrymildred Senior Member

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    Mine is almost all stop and go, but I still try to minimize braking and coast whenever traffic permits. It helps the efficiency a LOT.
     
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  17. Salamander_King

    Salamander_King Senior Member

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    Instead of having to contend a stop and go traffic, my problem is usually other cars (pickup truck or SUV most of the times) tailgating me get so irritated if I try to coast too much, that I have to push gas pedal more often than I would like to.
     
    #177 Salamander_King, Jun 6, 2019
    Last edited: Jun 6, 2019
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  18. jb in NE

    jb in NE Senior Member

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    No you don’t. Let them tailgate. If you’re coming up to a red light they won’t get through the intersection any faster.
     
  19. Salamander_King

    Salamander_King Senior Member

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    Well, it can be a yellow light I am slowing down to "Yield" as law requires, but most drivers think yellow light means "speed up" to go through faster. Also, I slow down in anticipation of "STOP" sign at the intersection, again, in those cases, faster you get to the intersection, faster you will enter the intersection.
     
    #179 Salamander_King, Jun 6, 2019
    Last edited: Jun 6, 2019
  20. jb in NE

    jb in NE Senior Member

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    If I'm not impeding traffic (and I adjust my driving where necessary to not be the rolling chicane), then I don't care if people tailgate me. If they hit me, it's their fault.