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Idea Bank: Household hybrids

The OEMs look to simplify recharging with plug & play technology
Thursday, January 1, 2009 - 01:00

The OEMs look to simplify recharging with plug & play technology

Chevrolet Volt lithium ion technology hybrid batteries

When General Motors' chief executive drove to Washington D.C. late last year seeking federal funds to keep the company afloat, the big story for automotive enthusiasts, and much of the American public, was the prototype car he drove. Still targeted for release in 2010 (a date that may or may not slip, depending how GM fares financially), the Chevy Volt represents the next generation in hybrid vehicle technology.

Until now, the economics of hybrid vehicles such as the Toyota Prius have been a bit problematic for the buyer. Today's hybrids, which switch back and forth between gas and electric power, can offer substantial savings on fuel. Unfortunately, it takes a long time for the savings to cover the higher up-front cost in comparison with equivalent gas-powered vehicles. The Chevy Volt ultimately could change that through a new approach that should reduce fuel consumption even further.

The Volt is expected to rely much more on electric power, using an approach that goes by a variety of names, including "extended-range electric vehicle," "series hybrid" and "plug-in hybrid/electric vehicle (PHEV)." The latter refers to the fact that, unlike some of today's hybrids, the Volt must be recharged overnight. But unlike some vehicles that operate only on electricity, the Volt does not require a special charging station. It plugs into a conventional 110V or 220V electric socket, charging in up to eight hours at 110V power or in about three hours using 220V.

After charging, the Volt operates for the first 40 miles entirely under electric power. The system then taps into a fuel-powered motor, but it is only used to recharge the battery. The vehicle continues to run on the electric motor. GM notes that because 75 percent of Americans drive less than 40 miles a day, many of them would need almost no gasoline if they were to choose the Volt. Still, by extending range beyond 40 miles, the vehicle also should be more attractive than a purely electric vehicle, which typically has limited range.

The long-term price of the Volt and similar vehicles including a planned Saturn Vue PHEV and anticipated PHEV offerings from Toyota and others will depend, in large part, on advances in the large on-board battery. These will need to deliver considerably more power than the already-large batteries included in hybrids currently on the road.

"The total energy in a Prius battery may be equivalent to maybe a half-gallon or gallon of gas," observes Jack Nerad, executive market analyst at Kelly Blue Book of Irvine, Calif. "What you're looking for to get a range of 40 miles may not be 10 times as much, but you're getting close."

The nickel metal hydride technology used in today's hybrid batteries won't be up to the task, developers agree. Instead, automakers are looking at lithium ion, a battery technology that already has reduced the size and increased the power of cellphone and other small consumer batteries.

Developers hope to get battery costs to between $5,000 and $8,000 by 2010 and between $3,000 and $5,000 as the technology matures over time.

Adapting lithium ion technology for use in PHEVs entails a key challenge. Cellphone-size lithium ion batteries typically use cobalt dioxide for the cathode material. The use of that material in a large-scale battery could cause the battery to rupture, explode or even catch fire in the event of a collision. The same thing could also happen if it became exposed to high temperatures.

The Tesla Roadster electric vehicle, already on the market at a cost of more than $100,000, appears to have avoided these dangers by using nearly 7,000 of the small lithium ion batteries available today and using sensors, cell isolation and liquid cooling to address the volatility problem. But that approach is impractical for a mass market PHEV.

Different manufacturers are pursuing different solutions to the volatility problem. GM is focusing on two manufacturers — A123 Systems, which has employees in the United States and Asia and has received funding from several highly respected venture capital firms, and LG Chem, a unit of the Korean conglomerate that also makes cellphones. A123 hopes to address volatility issues by using iron phosphate for the cathode material and miniaturized components based on nanotechnology. For its part, LG is pursuing the use of manganese oxide spinel for its cathode material.

Lithium ion batteries also may find their way into traditional hybrid vehicles where they could offer a power or size advantage over today's nickel-hydride batteries. Mercedes-Benz, for example, has made plans to use lithium ion batteries from a joint venture of U.S. conglomerate Johnson Controls and French manufacturer Saft in the S400 hybrid with a 275 horsepower V6 engine that it expects to roll out in the U.S. in 2010. The Johnson Control/Saft partnership also has development contracts involving lithium ion batteries for PHEVs with Ford for fleet tests on the Escape, with the United States Advanced Battery Consortium and others.

Yet another approach to PHEV batteries avoids the use of lithium ion completely. Lithium polymer batteries, already used in electric model airplanes, may offer more promise than lithium ion batteries, argues Brian Hamman, an automotive consultant who answers technical questions for visitors who log-on to the Web site. "Lithium polymer batteries could hold more power per pound than equal size lithium ion batteries and they're even lighter," says Hamman, who predicts that carmakers may drop plans for lithium ion batteries and instead substitute lithium polymer.

Requirements for repairing these vehicles center around protecting the large on-board battery from intense heat in paint booths, notes Craig Van Bat-enburg, owner of the Automotive Career Development Center of Worcester, Mass.

Van Batenburg doesn't anticipate many additional handling requirements for PHEVs in comparison with traditional hybrids. A 2008 Morgan Stanley forecast expects traditional hybrid sales to ramp up gradually in the next decade. PHEVs are forecast to climb from just 5,000 units in 2010 to more than 200,000 by 2015 and to more than a million by 2020. That's some serious battery power eventually coming to your shop.

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