fter years of incubation in the laboratory, supercapacitors finally are emerging as a mass-market alternative to conventional batteries to power stop-start systems.
Supercapacitors are energy-storage devices that, unlike batteries, provide short but very high-energy bursts of power -- ideal for restarting an engine when the motorist lifts his or her foot off the brake.
This month, General Motors is rolling out 2016 model year Cadillac ATS and CTS sedans equipped with stop-start systems featuring supercapacitors produced by Maxwell Technologies, a company based in San Diego. Maxwell, a Tier 2 supplier, is shipping its supercapacitors to Continental AG, which is integrating them into an energy management system.
Those models feature a pair of supercapacitors mounted in the trunk near the starter battery.
"The supercapacitor can deliver its current very, very quickly," said Chuck Cook, a sales applications engineer for Maxwell. A supercapacitor can restart an engine within 400 milliseconds or so -- twice as fast as a conventional system.
"That's an advantage because the driver won't perceive any hesitation" during restart, Cook said.
Batteries, in contrast, typically store more energy but discharge more slowly.
The supercapacitors weigh only a pound or two and are durable enough to provide a decade of usage. But a pair costs about $35 to $40 -- a bit more than lead-acid batteries.
Automakers such as Mazda, GM and PSA Peugeot Citroen are installing supercapacitors in vehicles equipped with stop-start systems to extend the life of the starter battery.
In 2010, PSA began installing Maxwell's supercapacitors for stop-start systems, followed by GM this fall. Mazda Motor Corp., which uses supercapacitors supplied by Nippon Chemi-Con Corp., introduced them as part of a stop-start system called i-Eloop on the Mazda6 in 2012.
The auto industry is a relatively new market for Maxwell, which generated global sales of $186 million last year. The company launched in 1965 with a focus on exotic military applications such as "pulse" guns.
As the Cold War wound down, Maxwell introduced supercapacitors for windmills and diesel-electric hybrid buses. In 2009, the company began developing automotive applications and teamed up with Continental.
In 2010, the German mega-supplier integrated Maxwell's supercapacitor into a stop-start system for PSA, followed by Cadillac this year. Last year, Continental announced its factory in Budapest, Hungary, had produced 1 million stop-start systems.
Maxwell is starting to line up new customers at a time when stop-start systems are catching on in the U.S.
By 2020, roughly 35 percent of vehicles sold in North America will have stop-start systems, up from 10 percent this year, predicts analyst Dave Alexander of Navigant Consulting, a Chicago research firm.
The stop-start system designed for PSA "has been a success in Europe," Alexander wrote in an email to Automotive News. "Finally [Max-well] has won a new customer. ... I do think there is potential for further market share gains."
Automakers are adding the technology to meet a 54.5 mpg corporate average fuel economy target by the 2025 model year. The EPA estimates stop-start systems can improve fuel economy by 4 to 5 percent.
But Maxwell will have to compete for this business against Johnson Controls Inc. The Milwaukee-based battery maker has developed an improved lead acid battery -- called an absorbent glass mat battery -- designed to handle the frequent engine startups required by stop-start systems.
Maxwell hopes to position its supercapacitor as an alternative to JCI's batteries. Its partnership with Continental could help Maxwell gain access to potential customers.
"I suspect we can really start going after market share because of [the supercapacitors'] performance, weight reduction and durability," Cook said. "Some car companies are afraid of the initial cost. But over the long run, they're going to find that this solution is economical." c