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100 MPH and 100 MPGe
Here is a link to my new blog at EV World posted yesterday. Phil Knox helped me write it.
100 MPH and 100 MPG http://i1378.photobucket.com/albums/...ps5d02ek17.jpg This image is of the Aero and Rolling Resistance graph for the 1996 Honda Accord our blog article is based on. The math essentially converts the metrics on this graph to our hypothetical Cd 0.12 Chevy Bolt using the conversions outlined. |
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Parking your pick up truck in favor of any other vehicle would be a good step.
. The Volkswagen XL1 made it to cd.189. . http://ecomodder.com/forum/showthrea...ery-25024.html . |
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Engineers work with Btus and all energy/power relationships can be related to Btus,making the transition between talking about BEVs and ICEs more transparent by the relationship to brake horsepower/road load,which all vehicles share. The EPA has provided the MPGe already.We're just expanding upon it. On a Btu-to-Btu basis,the LEAF and BOLT both share a 0.1397 lbs per bhp-hr BSFC. If your ICE car's engine and drivetrain were as efficient as that of the Bolt's powerplant/powertrain ,you could expect 3-X mpg from what you experience today. That's all we're saying.All the caveats are mentioned in the preamble to the guts of the article. |
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We're interested in going beyond the XL1,aerodynamically. Volkwagen's Hucho mentions that we can think about automobiles with Cd 0.08.We're being conservative. |
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*Within the study of thermo,engineers,or physicists are introduced to the 2nd Law of thermodynamics,which introduces the concept of 'Entropy'. *Entropy has to do with how much work can you get out of a system,with respect to how much energy you're putting in. *Understanding thermal and mechanical efficiency requires that you understand entropy. *Allowing any high school student to graduate without a knowledge of Entropy is the greatest disservice a public educator could bestow upon a student. -------------------------------------------------------------------------- *If you take the amount of Btus in a gallon of gas (111,836,for Regular Unleaded,10% Ethanol ) this can easily be converted to Kilowatt/hours. *Your gas tank capacity can be compared to a battery pack,or visa-versa. *If you compare the range of a BEV,compared to the average ICE vehicle,all else being equal,on a Tank-to-wheels,or Battery-to-wheels Btu basis,you find that the electric powertrain will get you 3-times farther down the road,for an equivalent amount of 'fuel'. *It's just straight engineering.No voodoo numbers manipulations. |
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But then I saw a pamphlet on how electric is more efficient that ICE. Volt and Bolt? Not so cool. Yes, they are more efficient (at least if you discount the efficiency of electricity generation, which varies a lot from one place to another). Yes, it's worthwhile to write about it because there are some who don't know this important fact. But the headline is wrong, MPG is not MPGe and the article doesn't deliver what it promises. |
100 MPH and 100 MPGe
I believe you are wrong about your concerns, which were addressed in the article. For some reason you want to include electrical generating and transmission loses in your calculations but seem to have no similar concerns for the well to wheel cost for fossil fuels at all? Why is that?
In the article I pointed out that for cost analysis charging loses should be included but no more. For the efficiency of the drive train we did not include them anymore then you would factor in the energy cost for delivering the gasoline to the gas station. This is not the way to evaluate a engine from a thermodynamic point of view. Better still with 5.1 KW of grid tie solar I would have no transmission loses if charging in the daytime. My export tariff is 8 cents per KWh so that would be my effective cost. The best GM could do was 100 MPG at 50 MPH with their 1992 Ultralight 2 cycle 3 cylinder engine. The 2017 Bolt can routinely pull over 100 MPGe at 62 MPH. Energy in to work out electric engines are a real winner when compared to any IC Engine. The batteries has been the weak link up until recently. It looks like the technology is now poised to take off in the market place and the reason it is doing so are becoming readily apparent. |
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But this is still a side note. MPG is used for ICE cars, MPGe for electric ones. By conflating the two you make the reader expect something you don't deliver and this is my main concern. |
The misconception is cleared up with a little further reading. Titles are not always 100% accurate for the content they contain. Plus, its been updated on the blog. Lets move on. Thanks.
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100 MPH and 100 MPGe
Your concerns have been addressed. The whole purpose of the article is to show that they are equivilent. One gallon of gasoline equals 32.77 KWH of electricity, period, end of story.
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I think what you do is wrong, but since you don't want fix it, there's nothing I can do. End of story.
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Sometimes 'Man Bites Dog' titles are chosen to attract a potential onlooker to potentially important information.Which is the entire premise of the exercise. Anyone who owns an automobile,of any kind,would benefit from this data if they didn't already know it.And I know of no other source for this sort of info other than EV World and Ecomodder. In 1991 it was Dr. Paul MacCready of AeroVironment, who turned some automotive data on its head,comparing the electric GM Impact and GM Sunraycer to gasoline equivalent vehicles of 100-mpg,and 400-mpg,respectively. In 1992,GM unveiled it's gasoline-powered Ultralite concept,of essentially identical aerodynamics of the Impact,with a rating of 100-mpg HWY,reinforcing Dr. MacCready's comment of 1991. This is all we're doing. You may be happy that your L.E.D. lighting is 7,000 % more efficient than a kerosene lantern of the same lumen output.We're attempting to contrast the difference in efficiency between internal combustion and electric propulsion in the same way. Engineering and physics plays back and forth between different metrics for conveying information,utilizing conversion factors to translate different technical 'languages' used in the marketplace. Please help me out by explaining,as specifically as you can,why,or 'where' you think the article is misleading.Thanks! PS It is the aerodynamics of the 1987 GM Sunraycer which undergirds the 100 mpg @ 100 mph capability. http://i1271.photobucket.com/albums/...d2/scan5_1.jpg |
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