Thread: False economy
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Old 05-24-2015, 06:42 PM   #11 (permalink)
2000mc
herp derp Apprentice
 
Join Date: Oct 2008
Location: Lawrence, KS
Posts: 1,049

Saturn-sold - '99 saturn sc1
Team Saturn
90 day: 28.28 mpg (US)

Yukon - '03 GMC Yukon Denali
90 day: 13.74 mpg (US)
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Quote:
Originally Posted by RedDevil View Post
A gallon of gas may deliver 33.7 kWh worth of energy, but most of that is transferred to heat and goes out of the tailpipe. More heat is lost through the radiator.
So only about 8 kWh is available to power the alternator belt - assuming 75% efficiency in that; only 6 kWh of electricity can be had from that gallon.

If you remove the belt and obtain 6 kWh worth of electricity (over time, at 200/300 W per hour) to power the 12V system from the battery and you lose 50% in charging that, you'd still need just 12 kWh from the mains.
That's a gallon saved for, what's your rate, a dollar and a half at 12.5 cents per kWh?
Well worth it!
So for every gallon of gas a car tries to turn into electricity, it puts out around 3kwh? So you replace buying a gallon of gas with 35 - 40 cents from your outlet. Sounds like it works out pretty well then.
Or saying you need 12kwh? Or more like $1.50/gal break even?


Last edited by 2000mc; 05-24-2015 at 06:59 PM..
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