Talking ultracapacitors, Chad Hall barely can control his enthusiasm.

“I have so much to say about this topic, I have to temper myself because I get so excited,” he tells WardsAuto in a phone interview from Ioxus headquarters in Oneonta, NY.

As vice president-marketing and product management and one of the cofounders of ultracap-supplier Ioxus, Hall is very much all-in when it comes to the energy-storage technology, and both his frustration and optimism come through in spades when he talks about the prospects for the devices in the light-vehicle market.

Frustration, because as Hall sees it, automotive engineers – particularly in the U.S. – have been missing the boat on what could be a far better, and cost-effective, solution to batteries in stop-start systems and other advanced vehicle-electrification applications in the works. Optimism, because signs are surfacing ever so slowly that resistance to the technology is breaking down – at least outside the U.S.

Unlike batteries, ultracapacitors store energy without a chemical reaction, so they can fully charge and discharge rapidly more than a million times without failure, meaning they can last the life of the vehicle. That ability to cycle quickly makes the ultracap a seemingly perfect fit for vehicle stop-start systems, where lead-acid battery performance, even with more advanced battery technology, has been disappointing so far.

Light-vehicle ultracapacitor applications have been rare to date, however, and all have involved cars designed and built outside the U.S. Mazda uses ultracaps to collect brake-regeneration energy to power accessories as part of its fuel-saving i-ELOOP system on the Mazda6 and other models. PSA Peugeot Citroen employs a Continental-supplied stop-start system with an ultracapacitor on a number of its vehicles. Lamborghini incorporates the same device on its Aventador super car, and Honda packages the devices into the stop-start system for its Fit in Japan.

Ultracaps have some disadvantages compared with batteries, namely their inability to store as much electrical energy. But OEs mostly have been reluctant to use them, advocates believe, because they are less familiar with the technology and have invested more heavily in advanced lithium-ion batteries. As automakers step up electrification, including an expected switch to 48-volt electrical architectures, Li-ion batteries present the biggest near-term threat to ultracap market penetration.

That landscape is what riles Hall, who says ultracaps ultimately offer automakers the most cost-effective solution to improving fuel economy.

Ford just put the EcoBoost (turbocharged engine technology) in,” he says. “That costs about $100 per 1% improvement in efficiency. They did the aluminum body on the F-150; that’s $150 per 1% fuel-efficiency improvement.”

Swapping an ultracap for underperforming lead-acid batteries in stop-start systems would boost fuel-economy savings from the current 1%-2% to 5%-7%, because the vehicle would be able to shut the engine down more often, Hall contends.

“That breaks down to (an investment of) $30-$40 per 1% increase, so it’s much cheaper.”

Ultracap per-unit cost is even lower than most industry insiders believe, the executive says, because Ioxus testing has proven there’s no need to include a DC-to-DC converter that can inflate the price tag to $500-$700.

He foresees a simpler system with low-cost electronic controls and a conventional battery to handle routine loads and a capacitor to supply electrical power to the stop-start system, e-turbo or power-steering unit.

“You need about $225 for the capacitor with a battery and electronics,” Hall says. “So it fits well within the (U.S. Advanced Battery Consortium’s) guidance on cost, performance, reliability and durability.”