Battery Tech Goes Back to the Future

By Al Vinikour

Too often when a goal is set, the end product seems to be the overriding concern. All-new is best; the previous is like yesterday’s news. Frequently this thinking is to the detriment of the masses and it’s generally not realized until much later. Fortunately, there are people who look at the past as a solid framework instead of something to be replaced as quickly as possible. One of those is Subhash Dhar, chairman, CEO and founder of Energy Power Systems (EPS). His solid belief in a “back to the future” approach to hybrid technology has propelled his start-up company to the point that it is close to achieving the sought-after breakthrough of dramatically lowering the cost of battery power that’s so vital to the development of low-cost, safe and reliable hybrid and electrical vehicles.

The lead acid batteries used in over 97% of the world’s vehicles have a 150+ year history. Only lately have we witnessed the first hybrids whose batteries were nickel metal hydride (like the Toyota Prius) and then succeeded by lithium ion (Chevrolet Volt). However, lead acid batteries were abandoned in pursuit of the latter two. Truth be told, 70% of battery cost is materials and there’s a finite amount of the materials dedicated to Ni-HM and Li-ion. This is not the case when it comes to lead. Additionally, 97% of lead acid batteries are recycled into batteries; NiMH is not. Furthermore, materials used in lead acid batteries are 1/10^th the cost of lithium-ion battery materials.

As common as battery-usage is in our everyday life, it still ranks among the least-understood facets. Today a battery has one function and one function only: to start a vehicle. The only power that’s used from the battery is the relatively minute energy drawn from the it to crank up the engine. After that job is done, the battery basically goes into hibernation but, while it’s sleeping, in reality the expended energy is being put back. One reason they have to be replaced so seldom is that a vehicle is not started up that many times in the course of a day. Ironically the battery could be disconnected when the vehicle is started, and the car will still operate. Consumers usually have the mistaken belief that the payback from driving a hybrid is instantaneous. Wrong again. Even the much-vaunted Prius has a payback period of 8-9 years.

Energy Power Systems claims it has elevated the power density (power, not energy) and cycle life of lead-acid batteries without jeopardizing the low costs that’s been its strong suit from the start. Dhar stated, “The conventional approach has always been to start with a chemistry that gives you high energy density and then hope you can reduce the cost. However, while the industry has overcome technical challenges of Li-ion, it never made much progress in terms of cost, so at EPS we turned that approach upside down — we started with low cost and then improved the technology so we can get the performance without disturbing the cost structure.”

The company’s approach is rather 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%, and Dhar hopes to be able to match the power density of nickel-metal hydride chemistries at one-third the cost. He said he could replace the 16-kWh lithium-ion battery in the Chevy Volt by combining the high power of a 3.5-kWh EPS lead-acid battery and high energy of a 9-kWh lithium-ion pack, and by doing so cut the battery pack cost from approximately $12,000 to under $6,000. Like all other new technologies, over time the costs would be driven further downward. At $100/kWh, lead-acid costs about one-seventh of what today’s liquid-cooled, lithium-ion battery packs cost. 

However, over the past decade automakers basically abandoned lead-acid battery technology and concentrated on the higher-energy, but much more expensive, nickel metal hydride and lithium-ion batteries. As an example, the price of an electric Ford Focus starts at $39,200 — more than double the price of a 2.0L gasoline engine that delivers 36 highway mpg. Even the most uninitiated can easily see the discrepancy. As Dhar has stated on numerous occasions, the technology has been there all along; it’s up to new advances on seemingly old technology to make extended-range hybrids and electric vehicles price worthy.

Recent high-profile bankruptcies have actually emphasized and confirmed Dhar’s belief that, contrary to what may be the industry’s premature departure from lead-acid technology this past decade, it would benefit from taking another look at the progress and technologies emanating from EPS’s developments. Dhar is certainly not against other development programs. Far from it; he’s very supportive of them. But he also is firmly convinced that the auto industry must become more pragmatic about what it can do during the next decade to reduce the battery’s cost burden on the vehicle. He believes options include using a smaller battery or reducing the size of the battery by a factor of three or four.

No stranger to this arena, Subhash Dhar was a leader of the team at Energy Conversion Devices that commercialized the nickel metal hydride battery now widely used in hybrid vehicles. His entire career has been spent in and around advanced battery-oriented companies. With the auto industry scrambling to find a better battery for electric cars, Dhar believes the timing is right for his company’s concept.