MPG in Hybrid Mode

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

  1. CEJ

    CEJ Member

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    You're suggesting that I exhaust the charge available for EV mode so that only HV mode is then possible and then run through a full tank of gas?
     
  2. Salamander_King

    Salamander_King Senior Member

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    Yap, but add one more step. Fill the tank to full after you exhaust EV range and set the trip meter to zero after filling. That way you can just drive on HV without any EV mode kicking in, and after you drive near the full tank (or can be less) fill the tank again to get your real calculated mpg by full tank method. Calculated mpg is usually lower than displayed mpg, but is more accurate.
     
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  3. CEJ

    CEJ Member

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    So this will eliminate possible errors that could be made by forgetting to push HV on for every sub-trip, extend the test over a larger distance, and provide a second check by dividing the total mileage travelled by the gallons actually assumed (that is, the gallons needed to refill the tank). Sounds like a plan!
     
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  4. CEJ

    CEJ Member

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    Make that consumed!
     
  5. Salamander_King

    Salamander_King Senior Member

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    Yes, I do this from time to time on my car to get accurate HV only mileage. I last did it when I changed winter tires to OEM all season tires a few months ago. I was getting less than 50mpg during winter with Micheline Xice3 winter tires on compared to ~60 mpg using the same method on OEM Dunlop Enasave All-Season tires.

    I keep a record of each fill-up and make a graph from a spreadsheet. In the graph below, the blue line shows my PRIME's lifetime mileage for each tank fill-up. The blue filled data points for mpg with OEM tire (no EV) and the red filled data pints are with winter tires (no EV). Uncolored data points all have a various amount of EV drive, thus mpg are inflated. The green line is calculated cost/mile with both gas and electricity paid for that period of the drive.

    Screenshot 2019-05-19 at 9.42.22 AM.png
     
    #45 Salamander_King, May 19, 2019
    Last edited: May 19, 2019
  6. bisco

    bisco cookie crumbler

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    on the pip, even if i push hv mode before driving, if there's any wall charge, the car will use a bit of it as the engine warms up, and will not return all the electrons.

    so the only way to get a true hv reading is as sk recommends above.
     
  7. CEJ

    CEJ Member

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    Wow, impressive and interesting! I'll need to fully digest the graph. Thanks for sharing. Had no idea tires could make that much difference. Turns out I had just fully charged the battery so for awhile I will be again pushing the HV button every time I drive. Found the Hybrid System Indicator screen, which can be customized to display the percentage of battery charge. It will interesting to see how much it varies from 100% as I drive: will it fall to 80% as some are saying or will stay higher as you find? Then I can exhaust the charge and proceed with your program for determining the HV mpg.
     
  8. Salamander_King

    Salamander_King Senior Member

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    Yes, I was quite surprised to find a large difference. When I used the Michelin Xice3 winter tires on my previous Gen3, the loss on mpg due to tire factor alone was negligible. I have a feeling PRIME and probably Gen4 is more sensitive to the tire difference. Of course, the difference was not totally due to tire alone. Weather and road condition during winter is quite different. Unfortunately, I did not check the HV only mileage on OEM tire for my first winter for comparison.
     
    #48 Salamander_King, May 19, 2019
    Last edited: May 19, 2019
  9. CEJ

    CEJ Member

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    Since I am new at this, l am curious as to how you can pick out and display the particular sentence or two you wish to respond to rather showing my entire post. Is there any place that explains the various tricks/shortcuts you can employ on the site?
     
  10. Raytheeagle

    Raytheeagle Senior Member

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    At the bottom of every post there is a quote button;).

    Use as you need:).

    There is also a website questions section, which is also helpful. Or just stick around and you’ll get the hang of it (y).
     
  11. Salamander_King

    Salamander_King Senior Member

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    If you use the +Quote button on the bottom of each comment, the entire comment will be quoted. You can also select a portion of the comment by highlighting it, +Quote | Reply button will pop-up. You can use Reply to post a comment to just that portion of a quote or You can use +Quote to make multiple quotes. Saved quotes will stay in memory until you use them by adding Quote button in your comments. See the screenshot below of your comment when I was selecting a portion and using it as a +Quote.

    Screenshot 2019-05-19 at 4.14.04 PM.png
     
    #51 Salamander_King, May 19, 2019
    Last edited: May 19, 2019
  12. CEJ

    CEJ Member

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    Thanks, Ray

    Thanks SK, as always, for your advice, help, and clarity!

    I have had my prime about 3 months now. A couple of times when I first start it in the morning, there is a distinct and fairly loud hissing sound. I thought it might be coming from the heating/AC vents but am not sure. After a minute or so it stops and everything proceeds normally. I also wondered if it could be coming from an outside source, but today it happened again. Has anyone else experienced this or know what it is?
     
    #52 CEJ, May 19, 2019
    Last edited by a moderator: May 22, 2019
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  13. Salamander_King

    Salamander_King Senior Member

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    Yes, PRIME makes many random sounds even when the car is off. The car scared me once when it started making high pitched whining noise late at night on our dark driveway suddenly. I was not in the car. Just walking by. Did not have a key with me, and car has been off and sitting there hours. After consulting the manual, I found out that was probably normal sound of a fuel evaporation leakage check.
    noise.png


    The sound you heard could be the heating/AC vents, or the vehicle proximity notification system sound or other various hybrid specific type of sounds listed in the manual. To tell the truth, I am not even sure what each of those sound is really like. :oops::oops::oops:
    sound.png
     
    #53 Salamander_King, May 21, 2019
    Last edited: May 21, 2019
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  14. jb in NE

    jb in NE Senior Member

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    Did you check for snakes under the hood? :)
     
  15. CEJ

    CEJ Member

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    Thanks, friend, for allaying my anxiety. I have only heard the hissing twice but it may be doing it at other times when I am not around and not just at startup. I have heard it do other whining and clicking so this must just be part of its repertoire.

    My project of fully charging up the battery but then running in HV mode continues while I observe the charge percentage on the HSI screen. In only 20 miles, it is has already dropped to 90% from 100%. I now have a piece of tape over the power button to remind me to push HV/EV button every time I start out (it's working). I notice if I hit HV/EV button too soon after the power button, HV doesn't take (could have been making this mistake earlier). Where in the world is the charge being expended? I would have thought that the charge reserved in the battery for the HV mode plus the generator and regenerative braking would be enough for HV. Somebody at TCS said sometimes EV clicks on in HV mode (?). How does the 12 volt battery come into picture?

    I look forward to implementing your plan of discharging the EV mode charge and then testing mpg in pure HV mode. More questions than answers so far. Stay tuned.
     
  16. CEJ

    CEJ Member

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    I am too afraid. You're welcome to come over and help.
     
  17. bisco

    bisco cookie crumbler

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    it uses some charge while the engine is warming up, and it uses some charge to make room for possible region.
    it does not go into pure ev while in hv, but it does maintain the 12v, although that probably gets replaced by gasoline, depending on how they programmed it.

    try not charging it fully, then drive hv and watch your percent.
     
    #57 bisco, May 21, 2019
    Last edited by a moderator: May 22, 2019
  18. jb in NE

    jb in NE Senior Member

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    I don't think this is the case. I've had full charge for many miles.
     
  19. bisco

    bisco cookie crumbler

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    interesting, maybe they've changed prime. i wonder what is eating away o/p's battery?
     
  20. jb in NE

    jb in NE Senior Member

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    This happens frequently - on a downhill in HV mode, the engine will shut off and the car will show running in EV, with HV selected as the drive mode.

    12 volt loads come from either the 12V battery (which is then recharged from the traction battery via the voltage converter) or directly from the voltage converter. The power for the voltage converter comes from the traction battery, which will be maintained by the engine if in HV mode.
     
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