MPG in Hybrid Mode

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

  1. Salamander_King

    Salamander_King Senior Member

    Joined:
    Nov 8, 2015
    4,196
    3,218
    0
    Location:
    New England
    Vehicle:
    2017 Prius Prime
    Model:
    Prime Premium
    @jb in NE wrote in other thread that he has already tested regen level under both ECO and NORMAL modes and found no difference. I would not think there is quantitative difference in those two modes in making energy for regen, but under NORMAL mode, I think it is easier to manipulate the ICE by getting into the RED zone and coasting to regen than using throttle damped ECO mode. Let me try on my way home today, and I will report the result here.
     
    jb in NE likes this.
  2. CEJ

    CEJ Member

    Joined:
    May 13, 2019
    130
    42
    0
    Location:
    USA
    Vehicle:
    2019 Prius Prime
    Model:
    Plug-in Advanced
    Is there much difference in mpg between the two modes? This is probably discussed in the ECO vs Normal thread you referred me to which I have studied yet.
     
  3. jerrymildred

    jerrymildred Senior Member

    Joined:
    Oct 28, 2016
    6,054
    7,636
    0
    Location:
    Tampa, FL
    Vehicle:
    2017 Prius Prime
    Model:
    Prime Premium
    In my experience, it's easier at low throttle settings to keep throttle changes to a minimum and drive smoothly which give me a little better economy. On the other had, when I need to accelerate more briskly, it can be harder at wider throttle openings to keep it out of the red power zone in ECO.

    Here's a drawing from the Gen 3 that shows the difference. As you can see, the throttle ramp is steeper in Normal and ECO as you approach WOT. But at low to middle openings, the ECO slope is more gradual.
    Throttle mapping.png

    Many, though, say they don't see any difference in gas mileage. I think it really is a case of "ymmv."
     
    Salamander_King likes this.
  4. CEJ

    CEJ Member

    Joined:
    May 13, 2019
    130
    42
    0
    Location:
    USA
    Vehicle:
    2019 Prius Prime
    Model:
    Plug-in Advanced
    Can you explain what the "red zone" is?
     
  5. Prius from Dad

    Prius from Dad Senior Member

    Joined:
    Oct 5, 2012
    724
    1,106
    0
    Location:
    Toms River, NJ USA
    Vehicle:
    2017 Prius Prime
    Model:
    Prime Premium

    It is the power zone in the HSI section of the MID.

    upload_2019-5-28_17-39-12.png
     
  6. CEJ

    CEJ Member

    Joined:
    May 13, 2019
    130
    42
    0
    Location:
    USA
    Vehicle:
    2019 Prius Prime
    Model:
    Plug-in Advanced
    Got it! Thanks much!
     
    Raytheeagle and Prius from Dad like this.
  7. Salamander_King

    Salamander_King Senior Member

    Joined:
    Nov 8, 2015
    4,196
    3,218
    0
    Location:
    New England
    Vehicle:
    2017 Prius Prime
    Model:
    Prime Premium
    OK, I am back home. I drove back home 18.4 miles on ECO mode on forced HV mode. I had 40% SOC when I got to work this morning (drove in EV all the way). Driving home, I did exactly the same as I did yesterday trying to maximize the regenerative braking. Yes, as jb said, the ECO mode is not much different from yesterday's NORMAL mode for regen ability. I gained 10% SOC on my way home. This compared to yesterday's 9% on NORMAL mode. The mpg was 61.4mpg ECO vs 64.9mpg NORMAL. I think the difference is within a margin of error.

    Although there are not much differences in mileage or regen amount, ECO mode with dampened throttle I had to push the pedal harder to get out of EV range as I predicted. After driving Normal for a few weeks now, I do think Normal is easier to control the gas level in all region of power bands from low to high.

    In any case, it is clear now the traction battery can be replenished by regen during forced HV mode. 10% in 18 miles on the terrain and road condition I usually drive.

    Screenshot 2019-05-28 at 6.05.16 PM.png
     
    jerrymildred likes this.
  8. CEJ

    CEJ Member

    Joined:
    May 13, 2019
    130
    42
    0
    Location:
    USA
    Vehicle:
    2019 Prius Prime
    Model:
    Plug-in Advanced
    Can you define "forced" HV mode? Also, there is an EV indicator on the HSI display which I assume goes on or off when you are in HV mode should it shift for a spell into EV mode . There is also an EV mode indicator in the Main Display screen. Should it disappear when the HSI one turns off? In other words, are the two indicators correlated. Not sure I am seeing this.
     
  9. Salamander_King

    Salamander_King Senior Member

    Joined:
    Nov 8, 2015
    4,196
    3,218
    0
    Location:
    New England
    Vehicle:
    2017 Prius Prime
    Model:
    Prime Premium
    "forced" HV, I just meant pushing EV/HV button to switch from default EV mode while still EV SOC is available. The top pic on #127 is the pic I took when I got to work this morning. Remember, I had 100% regenerated EV yesterday, I drove EV mode all the way to work this morning unbeknownst to me on NORMAL mode, thus EV mode icon but no Eco mode icon. The bottom pic is after I got home in the evening. I drove all the way home Eco Mode but in "forced" HV mode, thus Eco mode icon but no EV mode icon.

    The EV indicator you see in the HSI comes on only when you are driving EV either you are in EV/HV/EV Auto mode. In theory, if you are in EV mode with SOC left the EV indicator in HSI should stay all the time, but I have seen from time to time this indicator disappears especially if you switch back and forth between EV/HV manually. The two icons have no correlation.
     
    #129 Salamander_King, May 28, 2019
    Last edited: May 28, 2019
  10. CEJ

    CEJ Member

    Joined:
    May 13, 2019
    130
    42
    0
    Location:
    USA
    Vehicle:
    2019 Prius Prime
    Model:
    Plug-in Advanced
    I guess I am still a bit confused. I am referring to (1) the "EV" icon in HSI MID screen pasted on the outline of a car and (2) the "EV mode" icon in the main display right next to the "Eco mode" icon. Shouldn't these two EV icons either be both on or both off at the same time (on if you are in EV and off if you manually switch to HV, which, I think, is what you call "forced" HV)? This must not be the case because your last picture contradicts this and shows EVmode icon absent from Main Display but EV icon in the HSI MID display still showing (but you say you have seen it go away sometimes?)
     
    #130 CEJ, May 29, 2019
    Last edited: May 29, 2019
  11. jb in NE

    jb in NE Senior Member

    Joined:
    Apr 13, 2018
    2,235
    1,553
    0
    Location:
    Nebraska
    Vehicle:
    2018 Prius Prime
    Model:
    Prime Premium
    If you are in HV mode (the EV indicator next to the mode indicator is blank), the car can put itself in EV mode when needed (i.e when you are stopped, when you are going downhill, etc.). You can be in HV mode and the car will shift the drive mode between EV and using the ICE as needed.

    If you are in EV mode, the car will attempt to drive on EV only until the traction battery gets to an indicated 0%. If you are in EV Auto mode, the car will attempt to drive on EV only but if you lead-foot it this may trigger the ICE to start to provide more power.

    upload_2019-5-28_23-41-29.jpeg

    Look at pages 201-212 of your owner manual for more description of the Hybrid System Indicator which shows on the MID.
     
  12. CEJ

    CEJ Member

    Joined:
    May 13, 2019
    130
    42
    0
    Location:
    USA
    Vehicle:
    2019 Prius Prime
    Model:
    Plug-in Advanced
    Thanks!
     
  13. Salamander_King

    Salamander_King Senior Member

    Joined:
    Nov 8, 2015
    4,196
    3,218
    0
    Location:
    New England
    Vehicle:
    2017 Prius Prime
    Model:
    Prime Premium
    The EV/HV mode indicator in the main display will stay on as "EV MODE" as long as you have SOC left and you did not hit the EV/HV button to switch to HV (or to EV AUTO). If you do switch to HV MODE while SOC remains, then the "EV MODE" is off indicating you are now HV MODE (there is no indicator for HV MODE). OR if you deplete the SOC to 0% then it will goes automatically into the HV MODE and "EV MODE" is now off. On the other hand, the EV icon inside of HSI is ON only when battery is powering the car and ICE is OFF. There are 4 possible combination of those two EV indicators, being either ON-on, OFF-off, ON-off, OFF-on (capital letters for the Main display "EV MODE", small letters for "EV icon" in the HSI). All combinations do occur.

    In theory, if you are in EV MODE with SOC remaining, it should stay on with EV icon in HSI all the time. That's what you would see most of the times in the "EV MODE".
    EV ev.png

    However, if you switch to HV MODE, the "EV MODE" indicator in the main display is now gone, and you are no in HV MODE. At first when HV MODE first starts, ICE comes on and goes through the warm-up. During this time, power is still provided from the traction battery, however since the ICE is on, the EV indicator in the HSI stays OFF. If you continue to drive in HV MODE and warm-up is done, eventually you can get EV icon in HSI to come back on like the last pic shows. Also, during HV MODE, if you push the pedal too hard and get out out of EV zone, the EV icon in HSI will be off but in this case power comes solely from ICE.
    HV hv.png

    In some instance when ICE is on while your are driving EV MODE with SOC left, the EV indicator inside of HSI does disappear. This happens because, although you are using battery to power the car, ICE is still ON (for warm-up cycle or other reason). The picture below was taken shortly after the picture above after I switched back to EV MODE while the engine was still going through the warm-up cycle. This is rare, but you will see this happen from time to time.
    EV hv.png

    Finally, if you stay on the HV MODE after the warm-up cycle and if you drive within the EV power band indicated in the HSI, yet smaller EV icon will appear indicating that your are using battery power to drive the car in HV MODE.
    HV ev.png
     
    #133 Salamander_King, May 29, 2019
    Last edited: May 29, 2019
  14. Salamander_King

    Salamander_King Senior Member

    Joined:
    Nov 8, 2015
    4,196
    3,218
    0
    Location:
    New England
    Vehicle:
    2017 Prius Prime
    Model:
    Prime Premium
    Here is the pic of OFF-off instance when in HV MODE (despite having 100% SOC), and I pushed harder to get out of EV range in HSI, so now the ICE is ON and powering the car. (Picture taken on different day than above pics and I was driving NORMAL MODE.)

    HV hv ice.png
     
  15. CEJ

    CEJ Member

    Joined:
    May 13, 2019
    130
    42
    0
    Location:
    USA
    Vehicle:
    2019 Prius Prime
    Model:
    Plug-in Advanced
    The is a wonderfully clear, well-worded and illustrated explanation. You must be a teacher! (I nominate you to write the next user's manual--it could use some improvement; yes, definitely a compliment!). This is not a trivial car. My root confusion stemmed from the fact that I saw the HSI EV icon pop on when I first turned the car on and it stay on as I hit the EV/HV button to go into HV mode (even as the EV icon in main display went off). I just never looked back, I guess, to realize (duh!) that the HSI EV icon was in fact popping on and off fairly often at least for my in-town driving. It didn't first go off until I had driven a few blocks as I now have observed so I assumed it was always on.

    How exactly Is this different from pure HV mode (0% SOC) where charge is taken from the HV charge portion and where ICE and this HV charge work together (like in an ordinary Prius)? There are certainly times when ICE is not on when driving an ordinary Prius which I would think should be operating just like the Prime with 0% SOC. In other words, in the case of the Prime, the needed charge just comes from SOC instead from the allocated HV charge. Or possibly the charge is used more freely and often and for different purposes in the case of the Prime in HV mode with available SOC?

    By the way, the mystery of the "hissing sound" is solved. It is the background static from an ill-tuned-in radio station, which must have accidentally gotten turned on. I figured it out when I realized I could hear very faint voices in the background.
     
  16. Salamander_King

    Salamander_King Senior Member

    Joined:
    Nov 8, 2015
    4,196
    3,218
    0
    Location:
    New England
    Vehicle:
    2017 Prius Prime
    Model:
    Prime Premium
    Someone might have looked at the battery utilization during HV with SOC 0% vs SOC 10% or 50% or 100%, but I am not aware of any differences. I have not done much to look at the behavior of PRIME using more sophisticated tools like Hybrid Assistant and/or scangauge 2, although I have both gadgets, so I don't have any hard evidence, but just driving it feel not much different. That is driving PRIME on HV mode is the same whether SOC is full or half full or only 10% or 0%. I' remember that someone has looked at the real battery level during HV mode with EV SOC 0%, and the car can dip into the HV reserve quite low. You can do the same thing with EV SOC left, but usually, it will stay within 3-4% before ICE start to recharge. Someone with more technical experience may chime in on this.

    LOL. I guess, that noise is not a hybrid-specific sound that you would find in the manual.:ROFLMAO::ROFLMAO::ROFLMAO:
     
    #136 Salamander_King, May 29, 2019
    Last edited: May 29, 2019
    jerrymildred likes this.
  17. CEJ

    CEJ Member

    Joined:
    May 13, 2019
    130
    42
    0
    Location:
    USA
    Vehicle:
    2019 Prius Prime
    Model:
    Plug-in Advanced
    I think not. By the way, do you know what the HSI screen looks like if you're in HV mode with 0% SOC? Is the EV icon still there indicating when HV charge is being used to power the car or is it gone? I guess the ICE and the electric motor can possibly be working at the same time (can this happen in the nonzero SOC case?).
     
  18. Salamander_King

    Salamander_King Senior Member

    Joined:
    Nov 8, 2015
    4,196
    3,218
    0
    Location:
    New England
    Vehicle:
    2017 Prius Prime
    Model:
    Prime Premium
    Why do you think the battery management is any different in HV MODE whether you have SOC left for EV MODE or not? I have not seen or felt any difference in the car's behavior that would suggest the difference. The HSI looks the same under the HV MODE regardless of the SOC level. EV icon will come on and off while driving SOC 0%. And yes both ICE and motor can be working at the same time in HV MODE. Again this happens both SOC 0% or 100% if you put the car in HV mode. You can see how the energy is flowing during your drive in the MID or the big screen using "Energy Monitor".

    Screenshot 2019-05-30 at 6.27.04 AM.png
     
    #138 Salamander_King, May 30, 2019
    Last edited: May 30, 2019
    jerrymildred likes this.
  19. CEJ

    CEJ Member

    Joined:
    May 13, 2019
    130
    42
    0
    Location:
    USA
    Vehicle:
    2019 Prius Prime
    Model:
    Plug-in Advanced
    There seemed to be a difference in my albeit limited experience in that for non-zer0 SOC, the charge fluctuates up and down a bit but the trend is for it drop fairly quickly into the 80's and, unlike you, I have not been able to restore it (of course my in-town trips are shorter and engine warmup is at play). In pure HV case with zero SOC, under the same circumstances, the HV charge also fluctuates but soon returns to its initial value.

    I didn't remember how the HSI screen behaved in the latter situation.

    Anyway, I will be taking a 200mi trip today and we will see what that experience teaches me.
     
  20. jerrymildred

    jerrymildred Senior Member

    Joined:
    Oct 28, 2016
    6,054
    7,636
    0
    Location:
    Tampa, FL
    Vehicle:
    2017 Prius Prime
    Model:
    Prime Premium
    And that's exactly why your EV range (SOC) is falling. It's the short trips.

    As @Salamander_King pointed out, the car behaves the same in HV mode whether there is EV range available or not. When your EV range is used up and you're making short trips, that's reflected in worse gas mileage as the engine has to run more to restore the SOC to normal, whereas, if you have EV range available, any deficit gets discarded when you shut off the car.
     
    Curlyone and Salamander_King like this.
Loading...