MPG in Hybrid Mode

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

  1. jb in NE

    jb in NE Senior Member

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    Yes.
     
  2. CEJ

    CEJ Member

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    Update: Just finished 110mi in the Prime 2019 (in town, mostly trips of 10mi or less) in HV mode starting with battery at 100%. EV charge has now dropped to 54% with an average of 76mpg. This seems much different than what others are experiencing with 2017-2018 Primes. Next step: tomorrow I will switch to EV mode and quickly use up the 54%. Then I will go into "pure" HV mode and see what mpg I get. If I had exhausted the charge while in HV mode, I assume I would have gotten over 200mi at over 70mpg. The cost of 6.6kwh needed to fully charge the battery in this case should be small in comparison to savings in gas (assuming the "pure" HV mode gets only 50ish mpg).
     
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  3. Salamander_King

    Salamander_King Senior Member

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    Assuming your 110 miles actually had some EV drive using 46% of the traction battery, ~14 miles were actually run by battery power (30 miles EV range x 0.46). This makes your actual gas mileage ~65 mpg which is very doable with this car. Although I can keep full charge in the traction battery after a long HV drive on the same day, I have never used HV drive day after day with charge left in the battery as you did. With bisco's comment on PiP, this behavior may not be specific to 2019 model PRIME. Nonetheless, it will be interesting to find out what kind of mileage you will get on pure HV without any charge.
     
  4. CEJ

    CEJ Member

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    My questions are: what is this EV charge really being used for and why? If some portions of EV Driving are being inserted into the HV driving mode, why? One could just do this manually by pressing the HV/EV button from time to time and keep open the option of preserving the charge for later use. The TCS guy I talked said the EV charge used during the HV driving mode was supposed to improve the efficiency of HV driving, whatever that means.
     
  5. Prius from Dad

    Prius from Dad Senior Member

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    Actually it isn't the "EV charge" being used, it is the "battery charge available" that is being used. If the EV charge was not available then HV mode would use the HV charge available. The HV charge will charge back up during regular driving. It is this using and recharging the HV portion that increases your mpg's in HV mode. Depending on driving habits and weather, getting 70 - 80+ mpg's in HV mode is reasonable.

    I did the same 36 mile one way commute using only HV for 6 months (Jan. - Jul.). EV was used for the morning commute and HV for the trip home. The average was 70.07 mpg's with a high of 81.2, using HV only. YMMV
     
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  6. Salamander_King

    Salamander_King Senior Member

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    I just did an experiment driving on HV for my short commute with full traction battery at start and 32.3 miles EV range on GOM. With my driving condition, the lowest the battery level went down was 97% at 7.0 mile mark, but with ICE running and regen replenishing the charge, I was back to 100% by 16.6 miles. It was down to 99% when I stopped at 18.4 miles. The GOM at that point was showing 31.4 miles. It is 2.8% loss of the range on GOM compared to only 1% loss of traction battery charge parentage. Not sure where this discrepancy is coming from, but it seems reasonable to think GOM incorporated my HV drive into estimation of the future EV range. Meaning that after 18.4 miles of HV drive, GOM is now estimating 31.7 miles EV range from 100% charge compared to 32.3 miles EV range initially estimated before the HV drive.

    So, yeah, my 2017 PRIME unlike yours, does not dig into the traction battery during HV drive. Even a short trip. I will continue using HV for next few days to see if the traction battery level drops after a few days. BTW, this is without any HVAC (no heat or AC or fans) and minimal battery load from other electronics. I had the 11.6 screen off, head light off, no heated seat. Only thing I had on was BlueTooth audio to listen to my audiobook.

    IMG_20190524_070311-vert.jpg
     
    #86 Salamander_King, May 24, 2019
    Last edited: May 24, 2019
  7. CEJ

    CEJ Member

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    Your mpg seems pretty high for HVmode. Do you expect to drop lower as you put on more miles?

    Expect to be getting into HV mode with 0% EV charge sometime today. Very interested to see if mpg then settles into the 50's range or the 65 range as would be expected (as you said) if, in the earlier experiment, the charge was being used up by going into EV for some of the time.
     
    #87 CEJ, May 24, 2019
    Last edited by a moderator: May 24, 2019
  8. Salamander_King

    Salamander_King Senior Member

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    With my normal driving condition, getting 65 mpg is very easily done on my PRIME during summer. In fact it would take some effort to get lower than 60 mpg on this car. Remember this is displayed mpg. The real calculated mpg is about 5-7% lower than that value. I do not drive in city. There is no stop and go traffic to contend. My average speed today was 33mph with top speed ~50mph very briefly. If I was in hurry or had a big pickup tailgating me, the average would have dropped to lower 60mpg. Without that upper 60 to lower 70 mpg is very doable on HV only without any AC in mild temp season.

    As stated above @Prius from Dad.
     
    #88 Salamander_King, May 24, 2019
    Last edited: May 24, 2019
  9. CEJ

    CEJ Member

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    Impressive mpg's but you have been saying all along that it was doable. You are not that far under my 76mpg and my charge is being stolen along the way and your's is not. Wish I knew what was going on. GOM now reads 0.4 miles and the charge remaining 2%; since I started with about 37mi, these don't jibe just like your's didn't. So I now be in pure HV-land. We' ll see what happens!
     
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  10. Salamander_King

    Salamander_King Senior Member

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    My commute back home was 74.9 mpg HV only. The road back has less downhill at the end, and I did not recoup the initial loss of battery charge. Ended at 96% battery charge and 30.7EV miles left. I will not charge tonight and will see how much EV range stays with the car tomorrow.

    IMG_20190524_162616.jpg
    IMG_20190524_162705.jpg
     
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  11. vvillovv

    vvillovv Active Member

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    Another factor to consider is which drive mode (Power, Normal, Eco) is being used.
    I used to use Eco exclusively for the first year of so. I now use Normal almost exclusively
    as I evaluate EV HV modes and compare to what others find.
     
  12. CEJ

    CEJ Member

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    I have now gone 37.1mi in pure HV mode (0% EV charge) and in ECO mode with all-over average 71.8 mpg, which is consistent with SK's and other's results. (Surprised, by the way, that this is so much higher than the estimate on the sticker. Of course, colder weather would bring it down.) Still mystified why they have injected EV charge into the HV mode for the 2019's. It would, of course, save gas on a road trip, but you could accomplish this manually by shifting into EV mode for awhile. I suppose I could be inadvertently doing something crazy that is causing this. It is interesting to observe how the HV charge fluctuates in the bar meter, when EV charge is 0%. Don't know whether this is visible when the EV charge is non-zero.
     
  13. Salamander_King

    Salamander_King Senior Member

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    I did not drive today. After sitting on the driveway full 24 hours, it is showing exactly the same 96% battery charge level and 30.7 miles GOM EV range. No ghost battery use on my car like reported by someone in a different thread.

    IMG_20190525_141123.jpg
     
  14. Tideland Prius

    Tideland Prius Moderator of the North
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    I left the car sitting for 10 days at 33% and it showed 33% went I came back from vacation.
     
  15. Salamander_King

    Salamander_King Senior Member

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    Comment I read in other thread on 2017 PRIME (quoted on my #30 comment on this thread: MPG in Hybrid Mode | Page 2 | PriusChat) was that after the battery is fully charged and driving it HV only, the battery kept losing the charge down to ~80%. The loss included some phantom use during overnight parking. Similar behavior was observed by OP's 2019 PRIME. I don't think it is model year difference but seems to be different by the operator. In my case, so far in 2 days, 4% loss all during driving HV.
     
    #95 Salamander_King, May 25, 2019
    Last edited: May 25, 2019
  16. CEJ

    CEJ Member

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    I am beginning to wonder if there might be a software glitch in my 2019. Why should it be so different from 2018 and allow so much charge to be siphoned off with no clear benefit?
     
  17. Salamander_King

    Salamander_King Senior Member

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    Were you using any AC function (cool or heat or just fan) during any of those HV drives? Since some 2017 owners were reporting similar behavior, there must be something that consumes battery power even on HV. HVAC is most likely the culprit. Windshield Defroster and heated seats, rear defroster are other thing using traction power.
     
  18. jb in NE

    jb in NE Senior Member

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    I finally got around to digging through my Hybrid Assistant records from a recent trip. Here is an example - a few hours on the hightway at 73 mph, SOC stays almost flat. A bit goes into the battery at the end when I slowed down, probably for a rest stop.

    upload_2019-5-26_11-34-27.jpeg
     
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  19. CEJ

    CEJ Member

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    Not really. When I was doing HV starting on full charge, I wanted the results to be clean. Lately, when I have been on pure HV with zero charge, I have been using auto AC some, but still hitting low 70's mpg. You remember in my earlier experiment with non-zero charge that you estimated at one point that my effective HV mpg would be about 65 subtracting out the distance EV mode was adding (I agree with your math). The fact that I am getting higher than that in pure HV mode suggests something is amiss. Also, I assume you are saying that in HV but with non-zero charge available, it will use that energy to heat and cool, etc., but in pure HV it must derive the energy from ICE working together with the HV charge.
     
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  20. bisco

    bisco cookie crumbler

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    i have to think user error. software glitches and model year differences are uncommon to the point of non existent.
    but i can't figure what you might be doing wrong
     
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