General Motors plans to sell an electric version of the Spark, a mini-car that it currently sells outside the United States. GM will sell the gasoline version of the Spark in the U.S. starting next year, and will follow with the electric version in select U.S. markets and around the world in 2013. The electric Spark will be powered by batteries made by A123 Systems, based in Waltham, Massachusetts.

The car is a departure from GM’s current electric vehicle offering, the Chevrolet Volt. For short trips—about 35 miles—the Volt can run on battery power alone. For longer trips, a gasoline engine generates electricity to power the car. The range-extending gas engine is meant to address one of the main drawbacks of electric cars—their limited range on a charge. But adding an engine, and the complex transmission needed to coordinate power from the engine and electric motors, adds significantly to the vehicle’s cost.

That added cost seems to be hurting sales. The Volt was released at the end of 2010 at about the same time as the Nissan Leaf, an electric vehicle powered by batteries alone, and which has a range of about 73 miles per charge. The Volt costs $39,995, down from $41,000 originally, compared to $35,200 for the Leaf. This year, drivers have bought almost twice as many Leafs as Volts. As of the end of September, Nissan had sold 7,199 Leafs, compared to GM’s sales of just 3,895 Volts.

For much of that time, the Volt was only available in some states, but even with the car now available nationwide, it looks unlikely that GM will achieve its goal of selling 10,000 Volts this year, says Michael Omotoso, senior manager for powertrain forecasting at J.D. Power and Associates. “They may have to lower the price more to compete with the Leaf. Although the cars are different, consumers are comparing them head to head.”  [Update 10/17: GM says it expects to meet its target of 10,000, and says the sales numbers to date are in part the result of a temporary manufacturing shut down due to retooling at the factory that makes the Volt.]

GM says it decided to build the Spark EV to address anticipated demand in densely packed cities, particularly in Asia and Europe. A spokesperson for GM says the price of a battery-only vehicle will attract customers who don’t have to drive very far and won’t mind the limited range and need for frequent recharging. He also says government policies in places such as California and China can favor battery-only vehicles.

GM has been testing electric versions of three of its cars in small trials in India, China, and South Korea, and will use what it learned there about driver preferences when it engineers the Spark EV. GM won’t say yet how many Spark EVs it intends to make, or exactly where it will sell them. 

GM also plans to use a different battery supplier for the Spark than it uses for the Volt. For the Volt, it uses batteries made by LG Chem, a Korean company, although it had considered using batteries from A123 Systems—a comparatively new battery company at the time—which uses a novel, nanostructured electrode material for its batteries. Both LG Chem and A123 Systems produced full-sized Volt battery systems for testing.

“At that point, LG had a more mature manufacturing base for the Volt,” says Ronn Jamieson, GM’s director of global battery systems engineering. “A123 has significantly progressed in manufacturing since then,” he says. With the help of federal and state funds, A123 has built battery factories in Michigan, it can now make 30,000 electric vehicle batteries per year, and it has supply contracts with several automakers, including BMW, Fisker Automotive, and the large-vehicle manufacturer Navistar.

Jamieson says the A123 batteries were a good fit for the Spark EV in part because of their good energy storage, a key in a battery-only vehicle. A123’s lithium-ion electrode materials—made of lithium iron phosphate—actually store less energy than some types of lithium-ion battery by weight. But more of that energy can be used because the chemistry is more stable, Jamieson says. For some battery materials, only 50 to 80 percent of the energy can be used—discharging the battery more can damage the electrode materials and shorten the life of the battery. A123’s batteries can be discharged 90 percent or more.

In part because the Volt has been engineered to accommodate the specific characteristics of the LG Chem batteries, Jamieson says, GM will continue to use LG Chem batteries for the Volt.