The reason for Dhar's approach is simple: Improvements in power density and cycle life can be realized cost effectively. A small, 1.5-kWh lead-acid battery can adequately power a hybrid, while cutting costs by 50 percent, Dhar said. He ultimately hopes to be able to match the power density of nickel-metal hydride chemistries (which are used in 95 percent of hybrids) at one third their cost.
The company's concept doesn't end there, however. Dhar believes EPS can use its lead-acid technology in plug-in hybrids by teaming it with a small lithium-ion battery. In this scheme, the small lithium-ion battery would handle the energy (range) issues, while the lead-acid battery would provide the power. As an example, Dhar says he could replace the 16-kWh lithium-ion battery in the Chevy Volt with a 3.5-kWh lead-acid battery and a 9-kWh lithium-ion pack. Doing so, he believes EPS could cut the battery pack cost of a Chevy Volt from approximately $12,800 to under $6,000.
In essence, Dhar's concept boils down to a simple idea: At $100/kWh, lead-acid costs about one seventh of what today's liquid-cooled, lithium-ion battery packs cost. Moreover, lead-acid has been around for a century and is well understood by engineers.
EPS is reportedly working out a development plan with the state of Michigan and hopes to set up manufacturing facilities in an old Ford assembly plant in Wixom, Mich., by 2014.
With the auto industry scrambling to find a better battery for electric cars, Dhar believes the timing is right for his company's concept:
The industry discarded lead-acid chemistry a long time ago because it didn't have the energy density for electric vehicles. But we think it's time for a paradigm shift. We need to start thinking about how to improve miles per gallon by combining combustion with electrons. Once you do that, it lowers the amount of kilowatt-hours that you need.