PARIS –SA doesn’t want to put all its electric-vehicle eggs in one battery basket.
While the French auto maker is committed to employing lithium-ion batteries from theMotor Co. Ltd.-NEC Corp. joint venture Automotive Energy Supply Corp., engineers also are developing a second source that would use a different technology.
AESC is developing Li-ion batteries using lithium manganese spinal (LiMn2O4) cathode technology, which is also the choice of the Korean battery maker LG Chem Ltd.Corp. will use LG Chem Li-ion cells for the Chevrolet Volt extended-range EV.
However,also is investigating an alternative technology using cathodes of lithium iron phosphate (LiFePO4), which is being developed by supplier A123Systems Inc. among others, says Jerome Perrin, director-advanced environmental projects for Renault.
GM also is working with A123Systems on potential future vehicle applications for its Li-ion batteries.
Renault plans to package Li-ion batteries itself in factories in France, much as GM will do in Michigan. The cells will come from suppliers in Asia.
While cells are critical, so is packaging.Motor Corp. engineer Gerard Killman, addressing an industry conference here with Perrin, says that while the chemistry in the nickel-metal-hydride batteries used in the Prius can’t be improved much further, there still is a lot to be done with packaging, even after three generations of the Prius.
The next-generationhybrid battery, he says, will have direct cooling in its power electronics, rather than a heat sink, which will save space and mass.
Perrin says the LiMn2O4 technology yields an energy density of 161 Wh/kg, while the LiFePO4 today holds only 134 Wh/kg. Renault considers both to be extremely safe technologies, Perrin says, with no danger of fire in the event of shorted circuits or overcharging.
Renault’s business plan for its EVs envisions batteries costing less than E300 ($406) per kilowatt hour in 2012, with a lifetime of eight years and a range of 62 miles (100 km).
Even then, Perrin says, the battery won’t be sold with the cars but rented for a monthly fee as part of a service package. A Li-ion EV battery is expected to cost about E7,000 ($9,465). While that can be hidden in the cost of a E100,000 ($135,000)roadster, it would add almost a third to the price of a car like a Renault Megane.
Renault is planning on volumes of at least 10,000 units for its EVs: the 2011 electric Kangoo and electric Megane to be sold in Israel and the 2012 purpose-built electric car.
Europe has begun moving forward with preparations for EVs and plug-in hybrids.
Renault,Motor Co., Adam Opel GmbH, Volkswagen AG, Toyota, PSA Peugeot Citroen, AG, Audi AG and Motors Corp. met in workshops for two days this week with European power companies to discuss establishing a European standard for recharging and communication.
Killman, the Toyota engineer, says the auto maker is not very interested in EVs and will spend its energy instead on increasing production of hybrids. Toyota sold 400,000 hybrids last year, and aims at 1 million annually in the next decade.
He says Toyota will stick with NiMH batteries because they are affordable, but it is experimenting with a double battery pack that would raise the electric-only range of its hybrids to about 6 miles (10 km).
“We strongly believe that long-distance driving is a requirement for mobility,” Killman says. But Toyota is considering the double pack because its customers like the EV button that allows electric-only driving.
“We want to determine how much range is necessary and still provide sufficient trunk space and not increase the weight and cost unnecessarily,” Killman says. A 2007 study in France with the French electric company EDF found that 55% of daily trips are less than 6 miles, he says.
In an interview after his presentation to the French automobile engineering society’s conference on power electronics, Perrin says Renault is working on improving the feel of regenerative braking in its EVs.
Braking will be standard at first, but for the second generation of electric cars, Renault engineers are working on decoupling the brake pedal from the braking action so that software can control the feel of regenerative braking. It won’t be a total brake by wire, Perrin says, but it will move in that direction.
Brake feel is being developed in Renault’s driving simulator at the Guyancourt Technical Centre.
“For electrical vehicles, the vehicle is different, and driving is done differently,” says Andras Kemeny, manager of Renault’s Technical Center for Simulation. “An example is engine braking, with just the pedal, or just using the low speed, which is more economical even for traditional cars, but the perception with an electric vehicle is completely different.
“For the electric vehicle, the prototype can’t go in real traffic…but we can generate different engineering specs (and) generate the right sound data. We have a very precise idea on what would be the vehicle behavior in acceleration, the noise and so on. The driver can drive the electric vehicle before it exists.”