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Nissan EV moves electric car closer to reality

Mon, 03 Aug 2009

It's called the Leaf in Japan, and whether or not Nissan's production electric car carries that name in the United States, the company insists that the car will be on the road before the end of 2010.

Slightly larger than the familiar Versa subcompact, the zero-emissions Leaf was unveiled Aug. 2 at a dedication ceremony for Nissan's new global headquarters in Yokohama, Japan. The Leaf's range surpasses the daily needs of all but the longest commuters, and it demonstrates once again that the oft-maligned auto industry is ahead of the game when it comes to clean air--or at least ahead of the electricity-generating industry in North America.

The Leaf EV is a zippy little hatchback, with decent room for five and excellent cargo space. Yet the biggest news--perhaps the closest thing to a breakthrough--lies in its battery pack. Unless the Chevrolet Volt hybrid beats it to market, the Leaf will be the first volume-produced road car with lithium-ion batteries.

Now familiar in laptops, mobile phones and other small appliances, lithium-ion batteries were long considered poorly suited for automotive applications. Nissan, however, has been developing them for the purpose jointly with NEC electronics since 1992. A plant manufacturing the batteries for the Leaf opened in Kama, Japan, in 2007, and a satellite factory is under construction--with the help of a U.S. Department of Energy grant--near Nissan's North American headquarters in Smyrna, Tenn.

The Leaf's battery is an array of laminated lithium-ion sheets manufactured primarily of manganese. Each sheet is a 12-inch-by-10-inch rectangle, about half an inch thick, and there are several stacked in each of 48 metal-encased modules that comprise the Leaf's battery (total weight about 390 pounds). Nissan says the lithium-ion batteries have twice the energy density of any batteries used in current automotive applications, with 24 kilowatt-hours of power at full charge and peak delivery of 90 kilowatts.

The lithium-ion pack charges and operates at lower temperatures than lead-acid or ni-cad batteries, according to engineers, and after five years of daily drain cycles, it retains 80 percent of its original capacity. It also currently costs about $10,000 to make, according to one Nissan engineer, though at the retail level, the battery pack will likely be leased to the EV buyer, so its cost won't necessarily be reflected in the car's price.

The most important characteristic of the lithium-ion battery pack is straightforward: It gives the Leaf a range of 160 kilometers per charge--a tick under 100 miles--in the typical urban cycle. And according to Department of Transportation data, 98 percent of all American drivers drive less than 100 miles per day.

Moreover, the lithium-ion modules gave designers considerable flexibility in creating the Leaf. The batteries fit in a purpose-designed electric vehicle frame, stacked in what is essentially a subframe between the wheels, under the interior floor plan. The design adds rigidity to the unit-body as a whole, and it does good things for weight distribution. As significantly, the batteries take virtually no volume from the conventional cabin space.

The Leaf's batteries are packaged in a swoopy, five-door body reminiscent of the Versa, only prettier and more aerodynamically smooth. The car unveiled at Nissan headquarters was very close to production trim, with a smartly designed interior focused on a Scandinavian-looking, touch-switch center stack. The Leaf offers slightly more interior volume than the Versa, with comfortable room for four adults and impressive cargo space. The trunk area dips deep behind the batteries, so there's plenty of room for gear even with the seats up.

The Leaf is motivated by a Nissan-developed synchronous AC motor, delivering about 107 hp (80 kilowatts) and 206 lb-ft of torque through a single-gear transmission to the front wheels. We sampled the package in a test mule on a development track, and to the extent that it transfers to the production Leaf, it's impressive. There's immediate--we mean immediate--response to the throttle, and stimulating, steady acceleration up to a top speed of about 90 mph. We'd estimate 0-to-60 mph times in the high seven-second range with two people aboard. The car is smooth beyond subcompact expectations and quiet, as one might guess.

On a standard 110-volt home current, the Leaf will charge from a fully depleted state in 16 hours, according to company engineers. With a 220 current (like the typical electric dryer), it charges in eight hours. Nissan has also developed a DC quick-charge station for fleet and public use that fills the batteries to 80 percent capacity in 30 minutes.

Every Leaf will have a nav system and vehicle-specific information-exchange software. With one button, the navigation map shows the radius of the Leaf's range according to the current charge level. At any point, the driver can enter a specific destination and the system will calculate whether there's sufficient juice remaining to reach it. The map also will show known public charging stations--as it might show gas stations in a conventional car--assuming a significant number of public charging stations eventually come on line.

A Leaf owner can program charging time in his or her garage to take advantage of off-peak rates. The owner can also program the climate-control system to start operating while the Leaf is plugged in, saving the battery for travel. These and other operations--including checking the state of the Leaf's charge--can be accomplished remotely with a cell phone.

Nissan is still a bit vague about its rollout plan for the Leaf--if it is indeed called the Leaf in the States. Nissan insists that the car will be available for fleet use before then end of 2010, with general retail sales in key markets eight months to 10 months after that. Nissan's next generation of lithium-ion batteries, which may double the car's range, according to the company, could be ready by 2012, when the Leaf should be available at dealerships nationwide, Guesstimates put the retail price between $24,000 and $30,000.

Nissan notes that the Leaf has no tailpipe, emphasizing the fact that it generates no emissions during operation. Of course, the powerplant generating the electricity almost certainly will create potentially unhealthy emissions, and obviously, C02. The vast majority of electricity generated in the United States comes from coal- or petroleum-fired plants, and the Leaf demonstrates that cars are getting there, whether the power grid is or not.

By J. P. Vettraino