Ultracapacitors chosen for braking system

Edited by the Engineeringtalk editorial team Jul 11, 2007

The 14+Stars enables standard gasoline and diesel engines to shut down during idle phases and restart instantly, eliminating fuel consumption and emissions anytime the vehicle is stopped.

Maxwell Technologies has signed a memorandum of understanding (MOU) with Valeo, covering a development collaboration to incorporate Maxwell's Boostcap ultracapacitors in Valeo's next generation Stars+X "stop-start" and regenerative braking system, which reduces automobile fuel consumption and emissions and powers additional electrical functions.

The new 14+X Stars (starter alternator reversible system) consists of a reversible starter-alternator, a multi-cell ultracapacitor energy storage module and other power and control electronics in a 14V architecture that enables standard gasoline and diesel engines to shut down during idle phases and restart instantly, eliminating fuel consumption and emissions anytime the vehicle is stopped.

Valeo estimates that the system can reduce fuel consumption and associated emissions by about 12% in normal operation and more than 20% in stop-and-go urban traffic.

The first generation Stars with start-stop capability, which did not include a dedicated energy storage component, was offered in certain European passenger car models in 2004.

The new 14+X architecture incorporates enhanced electronics and an ultracapacitor energy storage module that allows it to recuperate and store energy from braking, which otherwise would be dissipated as friction and heat in a conventional braking system.

The recovered energy is then available to power peak electrical loads such as de-icing and rapid cabin and seat heating and cooling, avoiding increased fuel consumption for such functions.

"Because its energy storage employs high-efficiency, low-cost, ultracapacitor technology rather than costly nickel metal hydride or lithium-ion batteries, Stars 14+X can deliver 80% of the benefit of a mild hybrid system at 20% of the cost", said Daniel Richard, Director, RandD Valeo Electrical Systems.

"Tax incentives and free access to high-occupancy vehicle lanes have helped to stimulate demand for current premium-priced hybrid cars as niche products, but we believe that mass adoption of low-emission vehicles and much greater benefits in reduced CO2 and other greenhouse gas emissions will be driven by the availability of more cost-effective hybrid architectures".

Richard also noted that the flexible 14+X system's ability to be adapted for integration with a wide variety of existing motor platforms and to be applied to any new fuel technology such as flex fuel will make time to market for new models incorporating it much shorter than more radical hybrid approaches.

Dr Richard Balanson, Maxwell's President and Chief Executive Officer, said that the MOU also covers terms of a proposed multi-year development and supply agreement through which Valeo will source ultracapacitors from Maxwell.

"This design win is the result of an extensive collaborative development effort, and it reflects the progress Maxwell has made in developing and manufacturing products that meet the very demanding performance requirements of the auto industry", Balanson said.

"We continue to work with automakers and other Tier 1 suppliers worldwide to enable new applications such as this one and achieve the broadest possible penetration of this large and strategically important market".