Lithium-ion Battery Development Wins Award for Conti

Continental claims the lithium-ion batteries it has developed offer significantly greater storage capacity compared with the nickel-metal hydride battery technology still currently used in hybrid vehicles. The battery’s energy density is said to be around 30 per cent and its power to size ratio some 50 percent greater, while still retaining its compact dimensions. Development work on this unit, which saw its series production debut in the latest Mercedes-Benz S 400 BlueHYBRID, took place at Continental’s Nuremberg, Germany facility, and the site now has a production capacity of 15,000 units per annum. Recently Conti’s Powertrain Division and its Hybrid & Electric Vehicles business unit were acknowledged for the battery’s development and series introduction with an award from a logistics and transports association located in the factory’s local region.

On July 8 the Nuremberg-based Center for Transportation & Logistics Neuer Adler e.V. (CNA) awarded Conti’s Powertrain Division the “Intelligence for Traffic and Logistics” innovation prize, a distinction granted on the basis of the jobs and sustained growth the battery project has brought to the region of Bavaria. The award ceremony was held at the Nuremberg plant in the presence of some 50 representatives. During the ceremony, CNA chairman Jürgen Nutz paid tribute to the technology developed by the company’s Hybrid & Electric Vehicles business unit, and stated that “an important milestone had been reached in Germany on the way to electrifying the passenger car drive train.”

Attention was also drawn to the major fuel savings made possible by the use of hybrid technology, savings which amount to around 25 per cent compared with the traditional petrol engine. “In two years, Continental’s lithium-ion technology will also be ready for use in the commercial vehicle sector”, said Hybrid & Electric Vehicles business unit head Jörg Grotendorst. “Our latest generation of powerful lithium-ion batteries prepares the ground for hybrid buses driven purely by electric power. This could lead to a future reduction in the level of pollutants and CO2 emissions, particularly in inner-city areas where pollution is such a sensitive issue.”

The lithium-ion batteries used in the Mercedes S400 BlueHYBRID enable the spacious saloon’s six-cylinder petrol engine to achieve a consumption rate of 7.9 litres per 100 kilometres, equating to CO2 emissions of 190 grams per kilometre. This will, comments Continental, make the vehicle the world’s most economical petrol-engine luxury saloon. The battery Continental has developed can supply sufficient energy for an electric motor to supplement the combustion engine’s power output by up to 19kW, thus producing a considerable fuel saving when accelerating or starting off. The battery is charged whenever the vehicle brakes or decelerates, for example when freewheeling up to a red light. This regenerative braking or recuperation is controlled by the power electronics. Like the integral automatic start-stop function which automatically switches off the engine when the vehicle comes to a standstill and switches it on again when starting off, recuperation is included as part of Continental’s hybrid modular system, which combines all the company’s hybrid technology expertise in a single package.

Conti notes that using lithium-ion technology in vehicles poses particular challenges: For example, it is vital that the battery functions safely and reliably throughout the entire service life specified by the vehicle manufacturer. A sophisticated battery management system ensures that this requirement is met. The electronics compare the battery’s overall condition, temperature and energy reserves against its age; while safety circuits prevent the energy storage unit from becoming too hot. A Cell Supervising Circuit monitors the individual cells and ensures their optimum interaction. According to Continental, this guarantees that the lithium-ion batteries will really last – with unimpaired functionality, power and safety – for the required ten years or 160,000 to 240,000 kilometres.

Series production of the battery began in the autumn of 2008, following a 3.3 million euro investment to develop a 300 square metre manufacturing facility at Continental’s Nuremberg plant. According to the company, existing production capacity can be doubled to 30,000 units a year at short notice should such demand develop.