Check math please - kWh to Ah - electric car

Gents,
In this article
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"The Leaf's rating is based on a formula from the E.P.A. in which 33.7 kilowatt
hours of electricity is equivalent to one gallon of gasoline.
"The tough part with an electric vehicle is we have no gallons. We have no gas,"
Mr. Perry said. "But we understand the need to provide a comparison and that's
what the formula does.""
I calculated that one "gallon" of gas is equal to 2.8 Ah. I don't want to show
my math because it might skew your calculation.
If the Nissan Leaf gets the equivalent of 73 MPG on its electric motor, does
that mean only a 2.8 Ah battery will last for 73 miles?
---FULL TEXT OF ARTICLE---
Nissan Says Its Electric Leaf Gets Equivalent of 99 M.P.G.
DETROIT ? The federal government has rated the Nissan Leaf, the battery-powered
car scheduled to go on sale next month in five states, as getting the fuel
equivalent of 99 miles a gallon, Nissan said Monday.
The Leaf?s fuel-economy label.
The Environmental Protection Agency, which tests vehicles for emissions and fuel
efficiency, has determined Leaf?s official range to be 73 miles on a fully
charged battery, much less than the 100 miles previously claimed by Nissan.
Both figures will appear prominently on the Leaf?s window label, which shows the
estimated yearly electricity cost as $561. The E.P.A. calculates annual fuel
costs as $867 for the Toyota Prius hybrid and $1,669 for Chevrolet?s Malibu,
which like the Leaf, is classified as a midsize car.
The E.P.A. puts vehicles through five tests to simulate varying driving
conditions and levels of climate-control usage.
Because drivers cannot simply stop at a gas station and refuel, the Leaf?s range
is expected to weigh heavily on shoppers? minds. Adding to any confusion they
might feel, the Leaf will have a second sticker from the Federal Trade
Commission ? it regulates advertising by alternative-fuel vehicles ? displaying
the car?s range as 96 to 110 miles.
?Driving behavior, temperature ? those things do affect your range,? said Mark
Perry, the director of EV and Advanced Technology strategy in North America for
Nissan. ?We?re trying to be very open so folks are making the right decision for
them. We don?t want them to be surprised.?
The E.P.A. calculated the 99 m.p.g. equivalent figure by combining ratings of
106 m.p.g. in city driving and 92 m.p.g. on highways. The Leaf?s rating is
nearly double that of the Toyota Prius hybrid, which is 50 m.p.g.
The agency has not concluded its tests of the Chevrolet Volt, a plug-in hybrid
that also goes on sale next month in parts of the United States. The Volt,
unlike the Leaf, has a gasoline engine that allows the car to remain operational
after the battery, which General Motors says has a range of 25 to 50 miles, is
depleted.
?Their calculation is a little bit more straightforward than ours, so I suspect
they may have gotten through the process a little faster,? a G.M. spokesman, Rob
Peterson, said in explaining why the Leaf results were finished first. ?At this
time we don?t have a definitive number.?
The Leaf?s rating is based on a formula from the E.P.A. in which 33.7 kilowatt
hours of electricity is equivalent to one gallon of gasoline.
?The tough part with an electric vehicle is we have no gallons. We have no gas,?
Mr. Perry said. ?But we understand the need to provide a comparison and that?s
what the formula does.?
Mr. Perry noted that electricity costs ? assumed to be 12 cents a kilowatt-hour
for the purposes of the label ? varied widely in different parts of the country
and in some cases depending on what time of day the car was plugged in.
The Leaf?s window sticker will list the car as needing seven hours to charge via
a 240-volt outlet and consuming 34 kilowatt-hours every 100 miles. It will show
the Leaf, which has no tailpipe, as receiving the best possible scores for
emissions of greenhouse gases and other pollutants.
Nissan dealerships in California, Oregon, Washington, Arizona and Tennessee will
start selling the Leaf in December. Sales will begin in Texas and Hawaii in
January, followed by additional states later in 2011.
Reply to
G. Morgan
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What is the battery's voltage? 2.8 AH is only part of the data.
Reply to
Michael A. Terrell
A gallon of gas contains around 35MJ or about 9.7kWh.
If the battery is ~3500V.
1) Your numbers are *way* off. 2) There ain't no such thing as a free tank of gas.
Reply to
krw
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Don't forget Friction dumbass. All cars have very high frictions eating = away your energy. That's why you're stuck in snow easily.
Reply to
Illegally Blind
snipped-for-privacy@4ax.com...
g away your energy. =A0 That's why you're stuck in snow easily.
You are an idiot. He did not say anything about friction. He declared the content of the energy source. You are even more stupid than theghost troll is, and that is some feat.
Reply to
KilRoy IsHere
12V.
Reply to
G. Morgan
I don't where I grabbed my numbers. :-)
Here is my real question I guess:
"The Leaf's rating is based on a formula from the E.P.A. in which 33.7 kilowatt hours of electricity is equivalent to one gallon of gasoline."
Given: 33.7 kWh = 1 gallon of gas
What size 12V battery would be required to drive the claimed 73 miles?
Reply to
G. Morgan
Put about 300 of those in series and you're close.
Reply to
krw
Whoops, looking again, I see that gasoline contains about 35MJ/l (not gallon), so make that 130MJ/gallon or about 37kWh. Close enough.
37kWh == 37,000VAH/12V = 3100Ah
Reply to
krw
Sounds good.
Wow.. so that's going to be a big ass one (physical measurements). I wonder how big it would be.
Reply to
G. Morgan
That is about 15 golf cart batteries, the typical electric car load but I bet these guys use lithium batteries.
Reply to
gfretwell
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Not possible idiot, your 12V is very weak, it can't even sustain your = car electrical 500watt's need for more than 12mn. What makes you think = it can move a vehicle? If you want it to move, you need 10,000 AH 12V = at least charged with 120 A for 8 hours.
Reply to
Illegally Blind

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