Is there a forumla to know the cost for each Empty-Full EV charge?

Discussion in 'Prime Main Forum (2017-Current)' started by stevepea, Apr 25, 2017.

  1. stevepea

    stevepea Senior Member

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    Is there a formula, where you could easily plug in (pun intended) whatever number your local utility charges for the electricity, to figure out how much it costs to do a full charge from empty to full?

    For instance, if the electricity cost is 17c, then what would a full charge cost? (Doing it overnight while you sleep, going from typical depleted to full)

    Thanks!
     
  2. bwilson4web

    bwilson4web i3 and Prime

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    6.4 * 17c

    Bob Wilson
     
  3. mr88cet

    mr88cet Senior Member

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    Is it 6.4 KWh useable for EV? I was guessing more like 5.5-6KWh, once you subtract out charging overhead and HV-operation space...


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  4. bwilson4web

    bwilson4web i3 and Prime

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    I measured it: Prius Prime Plus in my hands | Page 7 | PriusChat

    Correction 6.3kWh for a full charge in Rhode Island and 6.35kWh in Huntsville AL.

    [​IMG]

    Bob Wilson
     
    #4 bwilson4web, Apr 25, 2017
    Last edited: Apr 25, 2017
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  5. Lee Jay

    Lee Jay Senior Member

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    I only measured it once, but it was 6.6kWh (from L1) that one time.
     
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  6. bwilson4web

    bwilson4web i3 and Prime

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    @Lee Jay brings up a good point that there is some variability both in the battery, charging conditions, and systems making the measurement. So I am confident that 6.4kWh is a perfectly fine and usable value. It is subject to variability as someone pointed out that slower charge rates are less efficient that faster ones.

    Bob Wilson
     
  7. Lee Jay

    Lee Jay Senior Member

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    It's also variable based on the amount of hybrid-charge left in the battery when you shut off the car.
     
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  8. crewdog

    crewdog Acting Ensign Prius Prime

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    I recorded 6.41 kwh using a 120v evse metered thru a kill-a-watt meter once.

    Excellent point about charge left in hybrid portion of battery.

    our electric rate is 0.11/kwh with taxes, so a full charge of EV portion of battery costs about 70 cents at home.
     
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  9. bisco

    bisco cookie crumbler

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    are the ~15% charging losses included in the 6.4 figure?
     
  10. bwilson4web

    bwilson4web i3 and Prime

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    Yes although the losses vary by the voltage:
    • 240 VAC - home EVSE @16A (lowest)
    • 210 VAC - business EVSE @16A
    • 120 VAC - home EVSE @12A
    • 120 VAC - home EVSE @8A
    Bob Wilson
     
    #10 bwilson4web, Apr 25, 2017
    Last edited: Apr 25, 2017
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  11. martydallas

    martydallas Member

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    try this, I think this does what your looking for

    MPGe Cost Comparison Calculator
     
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  12. drysider

    drysider Active Member

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    The losses do not play a role in the electricity cost. You are buying both the energy used and the energy lost.
     
  13. mr88cet

    mr88cet Senior Member

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    I gather the OP's goal is to get a handle on the total cost, including charging in/efficiency.


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  14. drysider

    drysider Active Member

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    The total cost is what you take from the mains. It includes eventual losses. Of the 6.5 kwh you probably get 5.5 kwh or so in useful energy, but you pay for 6.5.
     
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  15. Lemooron

    Lemooron Junior Member

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    I have charged with 0 miles left 4 times 6.48 - 6.35 - 6.50 - 6.39 for an average of 6.43
     
  16. drysider

    drysider Active Member

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    Informed data is a great thing.
     
  17. CharlesH

    CharlesH CA HOV Decal #5 on former PiP

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    One of the reasons L1 charging is less efficient than L2 charging is due to the losses in the charger electronics, which are more or less constant per unit time, but L1 charging takes more than twice as long as L2 charging, due to the voltage difference and since at 120V, the car only accepts 12 amps, but accepts 16 amps at 240V.
     
  18. Lee Jay

    Lee Jay Senior Member

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    They're more likely to be constant per unit time only if current is constant. Lower current will have lower losses.
     
  19. bwilson4web

    bwilson4web i3 and Prime

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    I used th think the same until I looked at switching regulator data sheets.

    Bob Wilson
     
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  20. giora

    giora Senior Member

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    At 240V the charge from the wall (payable energy) is only about 6 kWH as reported by @GT4Prius
     
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