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Design News, February 2013

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bring to light Captain Hybrid designnews.com/blog/Captain_Hybrid Why Ford Chose Lithium-Ion for its 2013 Hybrids Accelerated life tests convinced Ford engineers that lithium-ion could maintain its performance over an eight- or 10-year life. by Charles j. murray, senior Technical editor , electronics &Test when ford motor Co. announced LED Curable Polymer System One Component LED401LV • Fast curing • Cures completely tack-free • Environmentally friendly • Optically clear Hackensack, NJ 07601 USA +1.201.343.8983 main@masterbond.com in 2012 that its new hybrids would use lithium-ion batteries instead of nickelmetal hydride, many experts raised an eyebrow. Lithium-ion had a reputation for high cost and unknown durability, largely because the technology was still comparatively new. In contrast, approximately 95 percent of full and mild hybrids up to that time had used nickel-metal hydride. But Ford engineers now say their decision to use lithium-ion was based on accelerated lab tests, called Key Life Tests, showing lithium-ion would actually be more durable than nickel-metal hydride over a long lifetime. The tests, combined with mountains of field performance data on nickel-metal hydride, convinced them that they could predict the eightor 10-year future of a chemistry that didn't even have five years worth of reliable field data. "We are really confident that our Key Life Tests are mimicking the duty cycle of some of our most stringent and abusive customers," said Kevin Layden, Ford's director of electrification programs and engineering. "Given that, we feel lithium-ion will be better than nickel-metal hydride." Ford's confidence in the technology is real.The giant automaker will use lithium-ion in the second-generation Fusion, C-Max hybrid, Fusion Energi plug-in hybrid, C-Max Energi plug-in hybrid, and the Focus Electric. The key to Ford's testing effort is a lab that was part of a $135 million company investment in engineering and electric vehicle battery testing. Using their battery test lab, Ford engineers believe they are able to accurately forecast the 10year, 150,000-mile life performance of lithium-ion. "Somehow, we have to take out the unused time when the customer's car is in a garage or parking lot," said Anand Sankaran, Ford's chief engineer for energy storage and high-voltage systems. From prior experience with nickelmetal hydride, Ford engineers knew their accelerated test results were conservative. Thanks to the availability of mountains of field data on nickel-metal hydride batteries with hundreds of thousands of miles, they had developed a good feel for the relationship between test and field performance. So when lithium's predicted behavior improved on that of nickel-metal hydride, the engineering team reasoned that it was time to make the switch. The company's engineers say the new breed of batteries will offer an improvement over nickel-metal hydride in a number of ways, including size, weight, fuel efficiency, and life performance. "We know that customers will have questions about these batteries," Sankaran said. "Will I have to replace my battery after eight years? How will lithium-ion be different than nickel-metal hydride?' Now we can provide a much more accurate picture of how it will perform." DN www.masterbond.com Design News | february 2013 | www.d esign n ews.com –22–

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