Friday, September 14, 2012

Motor Trend Attempts LA-to-Las Vegas Drive in Model S EV on One Charge

Motor Trend Attempts LA-to-Las Vegas Drive in Model S EV on One Charge:

Editors at Motor Trend were recently loaned a Tesla electric car to put to the test, so that they could determine whether or not it lives up to the manufacturer’s extraordinary claims. They were allowed to keep it for 3 days, so they attempted an LA-to-Las Vegas drive in the Model S… without recharging it.

Tesla Model S.
The Tesla Model S gets an EPA estimated 265 miles range per charge, and Tesla Motors claims that it travels up to 300 miles.

The test drivers made the trip without air conditioning and at relatively low speeds (as little as 52 mph on the freeway, but they cruised at 65 mph). They made the 211-mile trip from the outskirts of Los Angeles to Las Vegas, realizing before the end that they had a fair bit of range to spare, so they turned the air conditioner on near the end. It was simply too hot! (104°).
Here is a map of the area. The purple line is not necessarily the path chosen by the Motor Trend editors, but it is what Google suggested:

View Larger Map

Factors Affecting Range

In the video, they said the range plummeted as their altitude approached 4,000 feet, but they were going uphill. Driving uphill is not equivalent to driving at a high altitude. Altitude is simply distance from the surface of the earth and doesn’t greatly affect EV range.
Uphill driving certainly will affect range, because energy has to be used the whole time to keep the vehicle moving uphill, unlike a trip on a level surface which enables it to coast (due to its inertia), which actually lets them regain some of the energy that they used to accelerate.
This efficiency rule applies to all types of cars — use it!

Gasoline-powered cars are affected by altitude because of the fact that air density decreases as altitude increases, and the engines are not able to consume as much air. Electric vehicles don’t need air, so they should not be affected by altitude.
Slow traffic, which was encountered near the end of the trip also affects electric vehicle range, in two ways. 1) The more time the vehicle is at rest with the air conditioner on, the more electricity is wasted. 2) Stop and go traffic allows the regenerative breaking to do its magic. Which trumped the other in this story, I’m not sure.
It would have been much more realistic to make the trip with the air conditioner on, and at a higher speed, but hey, they did accomplish their goal!
Source: Autoblog Green

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