Advanced Automotive Battery Update 2006
By Bill Moore
With all the talk about plug-in hybrids and electric cars, driven by soaring oil prices and global temperatures, the key question remains, are electric vehicle (EV) batteries ready for "prime time"? To answer that question, we turned to the founder and organizer of the Advanced Automotive Battery Conference, Menachem Anderman to get his take on the state of battery technology, especially in the light of a recent series of EV announcements and debuts from the UK to California.
We began by talking about batteries for pure electric cars. As he did four years ago in a previous EV World interview, Anderman still sees the two best technologies being nickel metal hydride (NiMH) and lithium ion (Li-ion), no surprise there, other than everyone has been suitably impressed by the unexpected durability of the batteries. Toyota RAV4 EVs in daily service with Southern California Edison, the local SoCal utility, are showing remarkable reliability of over 100,000 miles on their original battery pack, far longer than anyone expected.
He is now reasonably confident that NiMH batteries will operate more than 5 years, though he's reluctant to say they'll continue to perform ten-to-twelve years out, at least in pure electric car applications where the duty cycle is much more demanding than in hybrids like the Prius.
He is confident that test data demonstrates the batteries in hybrids will last over eight years.
"The nickel metal hydride, as far as manufacturability, robustness, trouble-free, reliability and life potential, is looking quite good, specifically from the main producer, Panasonic EV Energy, who has definitely been able to provide very reliable batteries for many uses," Anderman stated.
What was surprising is the issue of metal commodity costs: the price of the nickel that goes into NiMH batteries. He said he was shocked to see the price of nickel at $25 a kilogram, when it had been $15 a kilo just two months ago, which was then considered very high.
"If we are talking $15 as a base rather than a short-term spike, the potential for cost reduction with nickel-based batteries is, unfortunately, limited." He sees all the cost reductions of the recent past make possible by improved manufacturing scale and automation being eroded by the rising price of the nickel, which comprises 60 percent of the metal in the battery.
He noted that when he participated in preparing the battery report for California's Air Resources Board (CARB) in 2001, the price of nickel was around $7 a kilo. While he explains that he's not a commodity trader, he believes that the demand for steel, especially in China, is what is driving up the price of nickel.
Anderman told EV World that metals traders are telling him that $15 a kilogram is likely to be the price of nickel for the next several years.
So, if we can't expect to see any significant cost reductions in nickel batteries, what about lithium-based ones? Surely they are the future.
Here the issue becomes a "larger question," he responded, noting that there's been a lot of progress made since our 2002 interview, but that the technology hasn't been "proven" for electric car applications.
"With lithium, we have to talk about four or five issues," he said. The first issue is battery life, which looks very promising. "The data looks reasonably good. The people who look at the data are convinced we'll get more than five (years) and hopefully more then seven or eight years… But we don't have eight years data, so there is some extrapolation involved.
"But, and that's a very big but, lithium life is very sensitive to the average voltage the battery is kept and to the maximum voltage the battery is charged and, unfortunately, the degradation at high voltage is calendar-based rather than cycling-based. So, it's very difficult to accelerate the data… The main component that drives the degradation is just time and voltage and temperature."
What this means is that there isn't any way to confidently accelerate the lifecycle of the battery to know what it will do five or six years out, especially when used in the high discharge/charge regimes expected for pure electric cars and plug-in hybrids.
"I know we are all excited about the opportunity to use lithium in plug-in and full EV (electric vehicle) where we can get much better range because of considerably better energy density, but life in this type of profile is still a concern."
Anderman explained that in practical terms, if an EV developer wants to take full advantage of the higher voltage capacity of lithium -- in the 4.1-4.2 volts per cell range -- in order to get maximum range, test data he's seen as recently as last week indicates that the battery will last only about three years (and it has to be kept in the 20-40 degrees C temperature range). Using lower voltage, which shortens the range of the vehicle, will extend the life of the cell out to maybe 6 years, he believes, which raises serious questions about both battery manufacturer and carmaker warranties.
To learn more about the challenges confronting the utilization of various advanced chemistries, as well as some of the old stand-bys like lead and cadmium, be sure to listen to this 38-minute MP3 interview in its entirety. Anderman discusses the advantages of range-extended plug-in hybrids that offer less battery-only range in exchange for greater fuel economy: the approach apparently now being taken by CalCars and E-Drive, as well as strategies of how to extend the life of lithium ion batteries.
Use the either the Windows or Apple Quicktime MP3 audio players in the right-hand column or download the file to your computer hard drive for playback on your favorite MP3 device. The file is also available using the following URL: http://www.evworld.com/evworld_audio/manderman2006.mp3