PiP Fuel Efficiency: Cost per Mile

Discussion in 'Gen 1 Prius Plug-in 2012-2015' started by JimPHL, Dec 7, 2012.

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  1. 3PriusMike

    3PriusMike Prius owner since 2000, Tesla M3 2018

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    But what is the source of this consensus? Measurements or white papers?

    3 kw-hrs consumed at the wall and 2.7 kw-hrs usable in the battery is 10%. I measure slightly better than this with 220v CharePoint. I measure slightl better than this with 110v KAW. I measure slightly better than this with 110v Watts Up.

    Mike
     
    #21 3PriusMike, Dec 10, 2012
  2. John H

    John H Senior Member

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    measurements by other PC members.

    when you are calculating from 2.7 -> 3.0 you would multiply by 1.11 (11%)


    when you have a 50% loss on a stock , from $10 -> $5, you need a 200% gain to recover from $5 -> $10. :)
     
    #22 John H, Dec 10, 2012
  3. 3PriusMike

    3PriusMike Prius owner since 2000, Tesla M3 2018

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    You charged with 3 kw-hrs, you paid for 3 kw-hrs. You got to use 2.7 kw-hrs. Therefore your losses were 0.3 out of 3. That is a 10% loss, IMO.

    In a theoretical system, let's say you charged with 10 kw-hrs and the battery only took 1 kw-hr. That is a 90% loss. The battery charging has only a 10% efficiency.

    (IMO, how much you need to get you back to the original amount, like in a stock, has nothing to do with it. You can never get back the energy lost; you used or spent some amount and only a fraction of it was credited towards useful work...and your efficiency is the ratio of the two. Your losses are the difference of the two.)

    Mike
     
    #23 3PriusMike, Dec 10, 2012
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  4. John H

    John H Senior Member

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    Most folks are using the kWh displayed in the PiP so the conversion is from battery to wall.
     
    #24 John H, Dec 10, 2012
  5. JimPHL

    JimPHL Member

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    John, Thanks for the feedback, and for your patience as I get my head around this.
    I've updated the log accordingly. Would you mind a quick sanity check?
     

    Attached Files:

    #25 JimPHL, Dec 10, 2012
  6. John H

    John H Senior Member

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    I think you want to multitply your HSM kWh by 1.15 to arrive at the wall/metered kWh (which is what the EPA uses for MPGe). If you have a separate kWh meter that could be more accurate but not as convenient as just using the HSM.

    Most folks have been using kWh/100 miles rather than Miles per kWh, although for in car I prefer the M/kWh.

    still recalcing...
     
    #26 John H, Dec 10, 2012
  7. JimPHL

    JimPHL Member

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    Got it. Thank you. Nice to have closure. I'm posting an updated version in case anyone is interested.

    Next step is to update the MPG spreadsheet that Tracksyde shared. That one is a weekend project.

    New weekend routine; clean the car, check the tires, update the MPG spreadsheet.

    I used to start that process with a fill up!
     

    Attached Files:

    #27 JimPHL, Dec 10, 2012
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  8. John H

    John H Senior Member

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    I have started adding my kWh to fuelly, on a monthly total, converted to gallons. I pay $4/month for an EV charging subscription which is why I do it monthly.

    fuelly has a way to SMS your fuelups so maybe you could create a cheat sheet to go from HSM kWh --> gallons and SMS your charging to fuelly. :)
     
    #28 John H, Dec 10, 2012
  9. ukr2

    ukr2 Senior Member

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    John,

    All of us with Kill-A-Watt meters are using the Wall value, not the PIP Display.
    I report both the Wall kWh and the PIP EV display on the MPG Spreadsheet.
     
    #29 ukr2, Dec 10, 2012
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  10. John H

    John H Senior Member

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    I realize that. Have you arrived at a suitable "conversion factor" for going from the HSM to wall? I think the spreadsheet uses 15% (1.15).

     
    #30 John H, Dec 10, 2012
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