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Old 03-17-2011, 09:20 PM   #17 (permalink)
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Originally Posted by ChazInMT View Post
Then there is the specific energy of the Gasoline itself that must be considered, I mean is there really enough chemical power in that gallon to transport a big ol thing 200 Miles?
1 Gallon ~36 kwh of chemical energy at the impossible 100% efficiency... no heat , sound ,vibrations, light from combustion, etc.... all 100% of the chemical energy goes to mechanical motion ... and there is no friction or losses of any kind to get that to the wheels.

To go 200 miles on that means no more than ~180 wh per mile... or ~5.55 miles per kwh.

If traveling no slower than 1 MPH that is a maximum of 180 Watts of power ... or about ~1/4 HP.

Traveling any faster than 1 MPH increases rolling resistance and aerodynamic drag... and reduces vehicle per mile efficiency.

The faster you travel your miles the more energy of your 180 wh per mile you could consume ... so if you averaged 2 mph you could consume as much as ~1/2 HP ... increasing linearly with speed ... while the aerodynamic losses increase exponentially with speed... you would have less than 50 HP to push you at speeds of 200 MPH.

If for a given vehicle we know the Aerodynamics profile ( Cd*A ) & Rolling resistance profile ( Cr*Weight) ... we can quantify the maximum speed ( under a given wind speed and slope conditions. )

We can make it easy for ourselves by using the donor vehicle spread sheet put together by the nice people at the diyelectriccar forum.

see attached file bellow.

A vehicle as light and aerodynamic as the Gen-1 Honda Insight operating at 100% efficiency 200 MPG ... would max out at about ~40 MPH with no slope and no head wind.

The largest energy consumer on the list ... the 1997-2005 Jeep Wrangler at 100% efficiency 200 MPG ... no head wind, and no slope ... would max out at about ~27 MPH.
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