Curing Range Anxiety

•September 2, 2009 • 3 Comments

Next year will see a sea change in American automobile scene. Plug-in hybrids like Chevy Volt and pure electric cars like Nissan Leaf and BYD E6 will start selling in the first determined effort to say good buy to our middle eastern overloards. The idea is that a Bush no longer has to hold the hand while walking with a Saudi King or an Obama doesn’t have to dutiful bow to High Oily Highness.

But there are a number of aspiring futurologists who claim that the world is afflicted with a strange disease called Range Anxiety – and because of that electric cars will not sell. The anxiety is so great that even if you regularly drive no more than 40 miles a day, a range of 100 miles on a charge is somehow impracticle.

Let us cure this disease by looking at some numbers. The data was compiled from the 2001 National Household Transportation Survey by the Department of Transportation, Federal Highway Administration. The pdf document is available here.

The numbers to look at are the Daily Accrued Miles per Day.

daily_accrued_miles

This shows that on a daily basis (the second column above) 91.4% of the days Americans drive less than 100 miles. In fact on 75% of the days they drive less than 50 miles. What this shows is if you have a car that gives 100 miles on a charge you can use it 90% of the days.  On those 10% of the days you have to either rent a car or if you have a second or third car, you can use it.

So, let us assume electric only cars with a 100 mile range are impracticle unless you have a second or third vehicle – since nobody wants to rent cars evrytime they want to drive more than 100 miles.

Now let us see  how many Americans have 2 or more cars. From this 2000 US census data we see that a full 57% of American households have two or more cars ! I see no reason why one of those can’t be a pure Electric Car.

vehicle_ownership

Assuming a round figure of 105 million households in America, we see that nearly 60 Million households are ready to own a Electric car with a 100 mile range. All they have to do is to be able to decide before they hop into a car and drive, whether they are going to drive less than 100 miles that day or more than 100 miles. Take the electric car if you plan to drive less than 100 miles, otherwise take the gas car. Hell, make than 80 miles – just to be sure. Take the BEV if you drive less than 80 miles otherwise drive the gas car.

There, Range Anxiety is cured.

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MPGe of Nissan Leaf and Chevy Volt : How GM-Volt.com got it wrong

•August 29, 2009 • 1 Comment

Dr Dennis Lyle of GM-Volt.com tried to calculate the MPG Equivalent of Chevy Volt, Nissan Leaf and Tesla Roadster using Progressive Automotive X Prize standard. But he got it wrong.

Automotive X Prize uses the below formula to calculate.

MPGe = (miles driven) / [(total energy of all fuels consumed)/(energy of one gallon of gasoline)])

They have also given an Excel Spreadsheet and a pdf document to help anyone calculate the MPGe of any vehicle.

To calculate the MPGe for an EV we need to know the claimed range for a given charge. In the case of Volt it is 40 miles, Nissan Leaf is 100 miles and Tesla is 244 miles. Let us take these numbers at face value.

We also need to know how much electric power is used to reach that claimed range. That is where things get complicated. Chevy Volt has publicly stated several times that they only use about 50% of their 16kwh battery i.e. 8 kwh. This is what Lyle uses to calculate the EV only MPGe of GM Volt as 170 MPGe (40 miles for 8kwh).

But, unfortunately, Lyle uses full 100% battery capacity of Nissan Leaf and Tesla Roadster to calculate their MPGe. To put is mildly this is comparing apples to oranges. No EV can use 100% of the battery – it will ruin it quickly.

Let us see this from another angle. At 40 miles / 8 kwh, Volt has a 5 mile / kwh efficiency. At 100 miles / 24 kwh, Nissan Leaf would have only 4 mile / kwh efficiency. How can Volt, a much heavier vehicle than Nissan Leaf because of all that gas engine weight, be 25% more efficient than Nissan Leaf in electric only mode ?

Let us say Nissan Leaf uses an aggressive 80% of the battery – instead of the 50% that GM-Volt uses. That makes them use 20kwh for their 100 miles range, giving them the same 5 miles / kwh efficiency.

In general EVs give anywhere between 4 and 5 miles / kwh. GM’s EV1 gave a little more than 5 miles / kwh since it had a very good coefficiency of drag and was a small two seater.

GM stated in in their press conference announcing their 230 mpg nonsense that Volt will give a combined city+highway efficiency of 25 kwh / 100 miles. This is 4 miles / kwh and would reduce their claimed 40 miles electric range to 32 miles.

For now let us stick to the city operation only – since both GM Volt and Nissan Leaf have claimed their per charge range with city cycles only.

Using this information, we get 170 MPGe for both GM Volt and Nissan Leaf in electric operation.

mpge

Next, we need to figure out the MPGe for Volt when driven higher than 40 miles. Lyle has done that using the trip distribution table given in the pdf document linked above to be 167 MPGe, assuming 50 miles per gallon for Volt in generator mode, which looks a little high – but we can let it pass. But the combined calculation is wrong, as shown below. Lyle seems to be using Distribution of Trips instead of Distribution of Daily Miles.

This pdf document (AXP COURSE DESIGN – BASELINE DRIVING STATISTICS) gives all kinds of statistics on trip lengths by urban and rural drivers. Automotive X-Prize stipulates 100 miles of driving for EV and PHEV vehicles. Using the below distribution of daily miles, we see that 70% of the daily miles are under 40 miles and 14.8 % are between 40 and 100 miles. Since we are here restricted to 100 miles, our distribution for the sake of calculating MPGe for the GM Volt becomes 83% under 40 miles and 17% over 40 miles. If you incorrectly use Distribution of Trips instead of Distribution of Daily Miles, you get 98% under 40 miles and 2% over 40 miles – which is wrong.

 trips

Now, getting back to the calculating overall MPGe of Volt, we have 170 MPGe 83% of the time and 50 MPG 17% of the time. This yields a combined efficiency of 149.6 miles for VOlt – let us say 150 MPGe.

So final figures would be : Chevy Volt : 150 MPGe and Nissan Leaf : 170 MPGe.

But there is actually something overlooked here. X-Prize clearly says, we need to figure out how much power is drawn from the mains while charging the vehicle, not just use what is stored in the battery.

The amount of electricity consumed will be measured from the plug (AC) to return the vehicle to the state of charge it started the stage with.

If we assume a 90% efficiency while charging the battery, the MPGe will reduce by about 10% from 170 MPGe to 150 MPGe for Leaf and Volt would be 133 MPGe.

Nissan Leaf : 150 MPGe

GM Chevy Volt : 133 MPGe

What is your political compass ?

•August 15, 2009 • Leave a Comment

Just a left – right political scale is too simplistic.

Atleast you should consider a two dimensional map like the one politicalcompass.org proposes.

The old one-dimensional categories of ‘right’ and ‘left’, established for the seating arrangement of the French National Assembly of 1789, are overly simplistic for today’s complex political landscape.

The X axis takes the economic views while the Y measures social attitude. You can take the 6 page quiz which will tell you where you fall.

 pcompass-scale

Here are the mapping of some well known historical personalities.

pcompass-gandhietc

And finally, here I’m.

pcompass-evnow

William Morrison & EV Now

•August 14, 2009 • Leave a Comment

The first electric car was built sometime in the last decades of 1800s. Infact gas cars came later. So what happenned – why are we still searching for a highway capable electric car with a decent range that I can buy NOW for a decent price ?

Made by William Morrison in 1891, some say the Morrison was the first electric vehicle in America. It had a four horsepower engine , and could carry 6-12 passengers. Top speed was about 20 mph. The batteries needed to be recharged every 50 miles.

Well, we have the same problem now as they had back then – batteries.

William Morrison of Des Moines is credited with building the first electric car in 1891. It was successful, except for two problems: the batteries were heavy and expensive, and it wouldn’t go very far on a charge. In 2009 Ford and General Motors showed their new line of electric cars at the Detroit Auto Show. They were as pretty as you can make a vehicle. But they have two major problems: the batteries are heavy and expensive, and they don’t go very far on a charge.