Use of Aluminum Could Reduce Cost of EVs by $3,000 Page 2

By Eric Loveday

Eric Loveday

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Eric Loveday is a car enthusiast with a love for everything automotive. He purchased a 1970 Chevelle at age 16, quickly outgrew its dated engineering... More

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Aluminum Association

“Plug-in and hybrid electric cars contain precious little, and quite expensive, ‘fuel’ in the form of batteries,” added Bull. “Therefore, every effort must be made to utilize this stored energy to the highest possible efficiency. The solution lies in lowering the vehicle’s weight with aluminum as part of a holistic approach to also include advanced powertrains and batteries, enhanced thermal management, improved aerodynamics, and reduced rolling resistance.”

Highlights from the Ricardo electric vehicle study, for the federal test procedure (FTP75) drive cycle, include:

• The driving range of the vehicles could be improved approximately equal to the mass saved.  Reduce the mass of the vehicle 20 percent, go 20 percent father. One example vehicle had the range extended from 80 to 97 miles.
• The heaviest vehicle in the study, at 1,822 kg, consumed about 300 Wh/mi, while the lightest at 627 kg consumed about 146 Wh/mi.
• Regenerative braking could recover about 65 percent of the energy associated with the vehicle’s momentum irrespective of the vehicle weight. But this is only about 15-20 percent of the total energy expended.
• For the lightest vehicle, about 44 percent of the energy is lost to powertrain inefficiencies, with 33 percent of the energy used to overcome air resistance, and only 24 percent is used to move the vehicle.
• As with conventional vehicles, the lighter vehicles have faster accelerations.

The purpose of the Ricardo study was to evaluate the impact of vehicle weight reductions on electric vehicle performance, range and battery size. The majority of the vehicle simulations were done using the FTP75 drive cycle with a few highway drive cycles.  In general, the relationships between vehicle mass, battery weight and energy, and range are linear up to the maximum range studied of 80 miles. At this range, the battery weight doesn’t grow enough to start a significant “weight spiral.” 

The study also examined the role of vehicle mass on regenerative braking; specifically the question of whether strong regenerative braking might lessen the impact of weight reduction.  This turns out not to be the case. All vehicles studied could recoup about 65 percent of energy associated with moving the vehicle. But the energy balance for each vehicle changes. As the vehicle gets lighter, less energy is required to move it, while the aerodynamic losses remain constant. For the lightest vehicle the aerodynamic losses are higher than the energy to accelerate the vehicle.  

Real world designs support the fact that lightweight structures are a significant enabler for these vehicle types. Examples include Tesla Motors’s Roadster, or upcoming midsized platform, Fisker Automotive’s luxury vehicle and Bright Automotive’s van. All are all using lightweight aluminum platforms for their vehicles.

“Many of the current hybrid vehicles are progressively adding lower weight components to improve the overall vehicle performance. When it comes to making electric vehicles more affordable and efficient, aluminum is proven to get you there with no compromises,” said Bull. 

For a summary of the Ricardo study, or general information on the advantages of aluminum for transportation applications, visit www.autoaluminum.org. For a copy of the full study, or to arrange media interviews on the subject, please contact Kristin Tyll at 248-824-8200 or ktyll@stratacomm.net.

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About the Aluminum Association

Through its Aluminum Transportation Group, the Aluminum Association communicates the benefits of aluminum in ground transportation applications to help accelerate its penetration through research programs and related outreach activities. The ATG’s mission is to serve member companies and act as a central resource for the automotive and commercial vehicle industries on aluminum issues. Member of the ATG include:  Alcoa Inc., Novelis Inc., Alcan Inc, Aluminum Precision Products Inc., Kaiser Aluminum Corporation and Sapa Group.

About Ricardo

Ricardo is a leading provider of technology, product innovation, engineering solutions and strategic consulting to the world's automotive, transport and energy industries. Combining business, product and process strategy with fundamental technical research and the implementation of large-scale new product development programs, Ricardo is able to take on the greatest challenges including business strategy and restructuring, process re-engineering, product design, development, engineering, testing and systems integration. More information is available at www.ricardo.com.