I was linked to this article the other day via Pinyadda. Great read – but take it with a grain of salt. The information they provide is straight – there’s no fluff or bias in the article. As far as talking about companies or locations with public EV charging stations, my thoughts (and the explanation thereof) are below.
I personally don’t agree with “time-based” fees for charging. That’s like saying ‘You were at the gas station for 8 minutes, we charge $2/minute, so your total bill is $16.’ Time isn’t what we pay for at a station – gas is, and it’s measured in gallons.
If you pump gas through a 1″ hose, it will take twice as long to get the same amount of fuel as if you had a 2″ hose. That’s near enough the same as the comparison between 120V and 240V charging – it changes the size of the “pipe” so that you can “pump” the electricity faster.
It’d take forever to fill a giant tractor-trailer tank with our little teeny car pumps – that’s why they have big, high-speed pumps to fill their 50-300 gallon tanks. EVs have very large batteries, equivalent to having a very large “tank” for your “fuel.”
While companies with public EV chargers may not be allowed to bill by the kilowatt-hour, I wonder if they could bill by the Amp? It’s just a math conversion away from being a kilowatt-hour, but it may be enough different in today’s lawyer society that they could get away with it.
Another thing – while their math is 100% spot on (no fluff), you can’t use it for EVERY scenario. Electric cars are all different – and actually have different efficiencies. Just as cars have differing MPG ratings, EVs use different amounts of Watt-hours per mile driven. To go with that, how you drive effects your “MPG” in an electric car same as it does in a gas car.
Efficient road EVs (not science experiment ones) use about 300 Wh/mi (0.30 kWhr/mi). Some of the most efficient use as little as 250 Wh/mi; “guzzlers” can be found that use over 350 Wh/mi. So depending on how efficient the car is, and how efficient the driver is, the same amount of electric will take the same car different distances.
They quote $1 for 5 miles in a Tesla Roadster at 120V. A different driver may get 3 miles for that $1 worth, or maybe even 7. The same rule applies if you have a different car. Take the driver that can make a Tesla Roadster go 7 miles on that $1 of electric. They’re getting 40% more range for the same amount; 40% more efficiency. If we then couple that with an EV that would go 7 miles with the same amount of electricity the Tesla uses to go 5, that’s another 40% bonus to the already increased range. So it’s not nearly as simple (or necessarily expensive) as they make it out to be.