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Measured effect of engine block heater on my MPG

Discussion in 'Gen 3 Prius Fuel Economy' started by mite66, Dec 17, 2010.

  1. mite66

    mite66 Junior Member

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    I've been logging all my MPGs in the last couple of weeks for my daily commute to work. I must say here that it's a very short trip (1.8 miles) and it barely gives the engine enough time to warm up, especially since the temperatures are quite cold these days here.

    But this scenario is perfect to really measure the benefit of the EBH during the 5 first minutes of any trip.

    I'm able to plug my EBH for two hours before my departure to work but don't run it for my way back home so I'm now able to compare my MPG results between those two situations. The temperatures are also often colder in the morning than they are for my way back so we"re allow to think that my morning MPG should normally by worse than my evening ones.

    So here's what I got:

    2 hours EBH: 40mpg
    Average outside temp: 15.3 F

    Without EBH: 35mpg
    Average outside temp: 22.5 F


    I'm sure that the benefit would also be there for longer distances since the coolant is still colder (according to SG II) upon arrival without EBH than it is with it.

    Note: In all cases, I haven't use the heater nor the rear defrost.
     
    #1 mite66, Dec 17, 2010
    1 person likes this.
  2. spiderman

    spiderman wretched

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    Interesting. Can you say that the two legs of the trip have very similar topology and stops?
     
    #2 spiderman, Dec 17, 2010
  3. mite66

    mite66 Junior Member

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    Yes they do, 2 stops and 5 traffic lights in each directions.
     
    #3 mite66, Dec 17, 2010
  4. Former Member 68813

    Former Member 68813 Senior Member

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    I totally belive you. My MPH in first mile was never better than 25 and MPG in the first 2 miles was never better than 38. Now it's much lower during winter. Basically, you use electricity rather than gasoline to warm up the engine. The side effect is much lower engine wear because as everyone knows, most wear happens during cold run (start up).
     
    #4 Former Member 68813, Dec 17, 2010
  5. Cpl Bloggins

    Cpl Bloggins New Member

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    Could you check your MPG while using defrost on Hi temp setting next week to compare.
    thanks!
     
    #5 Cpl Bloggins, Dec 17, 2010
  6. fuzzy1

    fuzzy1 Senior Member

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    As a check, it would be worthwhile to measure both directions on a day without EBH. Even a very small elevation difference can make a noticeable difference in mpg in the opposing directions.
     
    #6 fuzzy1, Dec 18, 2010
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  7. dsljay

    dsljay Junior Member

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    Nice work mite66. Did you calculate how much the two hours of electric costs? Money wise, is the ebh a winner or loser?
    Happy holidays, Jay
     
    #7 dsljay, Dec 24, 2010
  8. stpool

    stpool New Member

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    If he is at 10 c a kWh and the heater is 400 w for 2 hr that would be 8 cent. If he drove 5 days a week would be less than 50 cents a week
     
    #8 stpool, Dec 24, 2010
  9. mite66

    mite66 Junior Member

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    Thanks Jay,

    the answer is... nop

    In my case, the EBH cost more to operate than the very small amount of fuel that I save by using it. I do think that for longer runs, it would indeed make sense moneywise. althougth I doubt that the money saved will also compensate for the cost of the EBH itself. But anyway, we're talking pennies here and we all bought Priuses for one reason, and that's not to save money on fuel isn't it ? (unless you're a taxi driver and drive it 40,000 miles or more per year)

    By the way, I finally broke the 60mpg barrier this morning, that's my best result since I own the car (4 weeks). But then, I was cheating (using too much battery) and the very low car density helped me to avoid all the red lights :).

    And finally, Santa should bring me my Enginer 4kwh plug-in kit today :D. I'll probably be able to install it sometime next week and I'll post the results as soon as I get something.

    Merry Christmas to you all !!!
     
    #9 mite66, Dec 24, 2010
  10. Mendel Leisk

    Mendel Leisk EGR Fanatic

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    I worked out the cost per hour for a 400 watt block heater (for our previous HCHII) before: in our area it was under 10 cents per hour. Is the Prius BH about the same?
     
    #10 Mendel Leisk, Dec 24, 2010
  11. rebenson

    rebenson Member

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    Thanks for the information. I guess I need to look into adding this option... sounds like it would be well worth the investment.
     
    #11 rebenson, Dec 26, 2010
  12. markabele

    markabele owner of PiP, then Leaf, then Model 3

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    Want to bring this thread back from the dead and start a new discussion about any sort of cost effectiveness of using an EBH.
     
    #12 markabele, Sep 8, 2012
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