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.
I agree, Dennis. This doesn't look promising unless that are some technical breakthroughs to lower the cost of building the Volt. It doesn't look like high-volume consumer purchasing is going to save the day.
I suspect that the $40k retail price was chosen as the price they could eventually reach if development and volume go as per plan. Considering that the public has been reticent with $7500 off that number I think this will be a problem.
Mixing battery technologies seems to have the potential to reduce costs without hurting overall performance. Aren't marine deep-cycle batteries lead-acid ? The lead-acid seems like the answer to acceleration, while the lithium-ion is there for range.
Now this is a good engineering story. As we have debated hybrids and EVs, the issue has always been cost. The answer to the battery issue has always been lithium ion. This is not a technology I would embrace because of the cost.
By approaching the problem of cost rather than starting with a technology to apply, the EPS is solving the problem. I also like the hybrid lead acid and lithium ion idea. It is similar to a concept used in disk drives where a small solid state device is paired with a spinning drive to provide both speed and large storage at a lower cost.
I never thought I would hear about lead-acid batteries again. Traditionally, the chemistry isn't very finicky, but the cycle life is poor and the energy density is terrible. One bright spot in the chemistry is that the cells are easily recycled, with something like 97% of depleted cells being recycled.
For industrial control applications, or even a simple assembly line, that machine can go almost 24/7 without a break. But what happens when the task is a little more complex? That’s where the “smart” machine would come in. The smart machine is one that has some simple (or complex in some cases) processing capability to be able to adapt to changing conditions. Such machines are suited for a host of applications, including automotive, aerospace, defense, medical, computers and electronics, telecommunications, consumer goods, and so on. This discussion will examine what’s possible with smart machines, and what tradeoffs need to be made to implement such a solution.