If the battery is the heart of an electric car, the ultracapacitor is shaping up to be the butler.

The fast-charging, fast-discharging devices have largely played on the fringes of the technology market for the last few years, but ultracapacitors could start appearing in larger numbers in commercial products. In part, that comes from improvements in the technology and a push among ultracap makers to fine-tune their markets based on how ultracaps behave.

Ultracaps, for instance, likely won't run electric cars on their own, according to Chad Hall, COO of Ioxus, which today released a line of electric double layer capacitors. Although an ultracapacitor can be charged in seconds versus the several hours battery packs can require, the amount to power it would require to charge an ultracapacitor bank big enough to run a car would likely short out your house.

"I don't see that happening for many years," said Hall.

Instead, ultracaps could be used to replace the hydraulic pumps behind power steering or run the electric windows and entertainment systems. Foreign car makers are moving faster at figuring out ways to incorporate ultracaps than U.S. automakers, he noted.

The company is also running trials with a forklift manufacturer to employ ultracapacitors to provide lift power to electric forklifts, which in turn eases the pressure on the battery pack which runs the fork lift. Ultracapacitors could also be used to capture power in regenerative braking cranes and perform load balancing tasks at wind farms or utilities.

"If you need to start a motor, an ultracapacitor is a good way to do that," he said. "Ultracapacitors don't have a lot of energy. They are a power component."

Ioxus, which spun out of Custom Electronics, says its ultracapacitors can store about 30 percent more power than competitors and, just as important, are far smaller. Thus, more can be squeezed into a tight space.

Instead of graphene, a form of carbon some other ultracap companies are examining, the company's devices rely on porous granules of activated charcoal. The more pores, the greater the capacitance.

Hall also noted that Ioxus makes its ultracapacitors in the U.S.