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A Wh/Mile to Miles/kWh (or Wh/Km to Km/kWh) converter

Discussion in 'Model 3: User Interface' started by FalconFour, Oct 15, 2018.

  1. FalconFour

    FalconFour Supporting Member

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    tl;dr: miles/kwh converter

    Since I got the Model 3, I've been frustrated by the Wh/Mile display. Living with a Leaf since 2012, and living with MPG and the concept of "higher is better" my entire life, the whole idea of Wh/Mile and "lower is better" is completely nutty to me. Maybe the bulk of Tesla owners with an engineering background have just thrown up their hands and said "eh, well, it works" and perhaps came from a bigger conversion of gas->electric, but I'm... I'm electric->electric and it's not going so smoothly.

    To my shock and frustration, there seem to be no conversion utilities online, anywhere readily accessible. Google can't convert it, WolframAlpha can convert it but it has to think really hard about it, and there's some painfully awful interface at Aqua-Calc that functions like a slide-rule (go ahead, take the number you have, adjust the table's range to match what you have, then look your number up in the table)...

    How about a simple website with a single function - input and output?

    Done. miles/kwh converter

    Now there's one less thing you can't Google. ;)
     
    • Like x 3
    • Informative x 2
  2. PetersRD

    PetersRD Member

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    Slick, but he math is pretty easy. Divide 1 by your Wh/Mile with a decimal in front of it.
    224 Wh/Mi >>> 1/.224 = 4.464 Mi/kWh
     
    • Informative x 1
  3. FalconFour

    FalconFour Supporting Member

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    I wish I knew it was that easy by Googling it every which way in the past... even while developing it I was having a hard time figuring out the formula.

    Well, now it should be a lot easier to find ;)
     
  4. swaltner

    swaltner Active Member

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    ti-1200.jpg

    As was mentioned above, the units tell you exactly what to do.

    If your units are A/B (that's what "A per B" means) and you want to express it as B/A, simply divide 1 by the value.
    • 4 quarts per gallon -> 1/4 gallons per quart -> .25 gallons per quart
    • .25 gallons per quart -> 1/.25 quarts per gallon -> 4 quarts per gallon
    If you need to convert between different ways of stating the same value in different units multiple by the conversion factor
    • 8 quarts * .25 gallons/quart -> 2 quarts*gallons/quarts -> 2 gallons
    • 224 Wh * .001 kWh/Wh -> .224 Wh*kWh/Wh -> .224 kWh
    I know some people get frustrated with others on the forum being very pedantic about using proper units (kW vs kWh, etc...). This question is part of why we are sticklers about using proper units. When proper units are used, and knowing a few conversion factors, it's "obvious" what you need to do to make many calculations.

    For example, how long would it take me to charge my 75 kWh battery in the Model 3 when charging at 240 Volts and 40 Amps? 240 Volts * 40 Amps is 9,600 Watts or 9.6 kW - plug that into 75 kWh / 9.6 kW -> 7.8 kWh/kW -> 7.8 (kW * h)/kW -> 7.8 (kW/kW) * h -> 7.8 hours - Not a perfect answer to the question (voltage sag, charger inefficiencies, taper, etc...), but it's very close to reality.
     
  5. darth_vad3r

    darth_vad3r Well-Known Sith

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    LOL, but you can literally do this *with Google*. Just punch into the Google search term: "1 / (233 Wh/mi) in mi/kWh" and it gives you "4.29184549 mi / kWh"

    You can also cross-calculate things, like: "27 kWh/100mi in Wh/km" = 167.77 Wh/km

    Example search link:
    1 / (233 Wh/mi) in mi/kWh - Google Search
     
    • Disagree x 1
  6. ewoodrick

    ewoodrick Well-Known Member

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    Leaf 4 = Tesla 250
    Leaf 3 = Tesla 333
     
  7. brianman

    brianman Burrito Founder

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    That's sorta right, unless your first Wh/Mi is not 3 digits.

    "1000 / " is how I would phrase it to avoid confusion.
     
  8. MrABRanch

    MrABRanch Member

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    That converter is very helpful!
     
  9. hugh_jassol

    hugh_jassol Member

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    No offense, but all you do is take 1000 and divide it by the Wh/Mi number. No "utility" necessary. No engineering either. High school math.
    You effectively made a web page that can divide two numbers.

    1000 (kWh/Wh) / 224 (Wh/Mi) = 4.64 Mi/kWh.
     
    • Like x 3
  10. darth_vad3r

    darth_vad3r Well-Known Sith

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    1000 Wh/kWh ;)

    FTFY, Hugh Jass.

    Also, as I pointed out earlier, google does math and unit conversions for you :)
     
  11. milleron

    milleron Member

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    How about grade-school arithmetic?
    The conversion is about the most intuitive one imaginable.
     
  12. JulienW

    JulienW Active Member

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    I'm on the other side right now with an ELR and using the industry standard miles per kWh (seems like I will be forever the way Tesla is building whit interior). However I have always simply converted Wh per mile and vise versa by dividing to compare. It does beg the question. Why does Tesla use Wh per mile instead of just following the industry miles per kWh standard?
     
  13. darth_vad3r

    darth_vad3r Well-Known Sith

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    Because consumption comparisons make way more sense to our monkey brains than efficiency comparisons. Google "MPG illusion".

    TL;DR if you add or subtract 10% from your consumption, your costs are affected by the same +/- 10%. Easy. If you do the same with MPG efficiency, what effect does that have on your costs?
     
  14. hugh_jassol

    hugh_jassol Member

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    I guess. Google will also tell me how to boil water. And it still means I'm a goober if I need to do that.
     
  15. darth_vad3r

    darth_vad3r Well-Known Sith

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    Google can tell you what temp it boils at at what altitude though ... that's useful :)

    I find Google caclulator great to use when converting units and doing math at the same time, like my first example of converting kWh/100mi to Wh/km, it does all the unit conversions for me...
    "27 kWh/100mi in Wh/km" = 167.77 Wh/km
     
  16. JulienW

    JulienW Active Member

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    ....but we don't use ounces/gallons per miles (consumption). Instead have always used miles per gallon (efficiency).:eek:;);)
     
  17. darth_vad3r

    darth_vad3r Well-Known Sith

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    Just cuz you’ve always been wrong doesn’t mean you shouldn’t change.

    Not too late to change to km like most of the world too ;)

    Your avatar describes the situation aptly (-:
     
  18. JulienW

    JulienW Active Member

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    #18 JulienW, May 23, 2019
    Last edited: May 23, 2019
    Touché on the Imperial vs Metric and I wish we had made the switch. However are ICE cars in Canada rated liters per kilometer or kilometers per liter?

    So when talking you will say "I use xx liters per xx kilometers" instead of "xx kilometers per liter"."
     
  19. MNoICE618

    MNoICE618 Member

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    Well we are metric in Australia too; easiest way to convert is change units in display options and the consumption figures change real-time

    Toggle the setting as required. No data lost.
     
  20. darth_vad3r

    darth_vad3r Well-Known Sith

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    #20 darth_vad3r, May 23, 2019
    Last edited: May 23, 2019
    Yes, my prior car showed my consumption on the dash in L/100km.

    e.g. My prior car used about 8L/100km, my wife’s gas guzzling SUV uses over 12. A hybrid car might be 5-6. In the Model 3 I’ve gotten 159 Wh/km (or a more directly comparable 15.9 kWh/100km).

    At $1.50/L and $0.10/kWh I can easily compare and advocate to others ... my last car took 12c to go a km, my wife’s SUV takes 18c or more, and my 3 is under 2c. If we use my 3 for weekend errands now instead of the SUV we save 90% on gas costs (and that’s only if I don’t “gas up” for free at work ;))
     

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