Electric vehicles may well be the way of the future, but they have several challenges to overcome, including how far they can travel on a charge, and how much their batteries cost.
Both of those are directly tied in to weight, making lightweight materials integral to electric vehicle development.
That includes aluminum. A new study by the Aluminum Association’s Aluminum Transportation Group (ATG) found that the percentage of weight reduction is approximately equal to the range gained: Reduce the vehicle’s weight by 20 per cent, and its range can be 20 per cent longer.
With less mass to move around, a battery can also be smaller.
“A 10 per cent reduction in mass equals a four- to six-per-cent battery size reduction,” says Doug Richman, of ATG and vice-president of engineering of technology for Kaiser Aluminum.
“What we found was that by doing a full aluminum structure, the cost was estimated at a $630 premium over a steel structure, but it saved a minimum of $900 in battery cost. For every dollar you spend, you’re saving at least one to two.”
Smaller batteries not only cost less, but they’re easier to recycle once they reach their end of life.
How automakers will dedicate the reduction in each vehicle depends on the customer, Richman says. “The industry can take the weight savings as range or a cost improvement. The real stress right now for a full electric vehicle is range, and I’m sure some will pick range and stick with it. But some will stick with cost; customers will know the range is low but they want the lower cost. Either way, it’s a huge benefit. They can get the range without an increase in battery size, but if they need a lower-cost vehicle, there’s a strategy to get there.”
Lighter weight doesn’t just improve electric vehicles: A 10 per cent reduction in mass also provides a three to five per cent improvement in gasoline or diesel vehicles. However, in a conventional engine, as much as 65 per cent of the energy is lost to inefficiency, primarily in friction and heat, while an electric motor only loses about 35 percent.
“Weight reduction is more valuable in electric vehicles because there’s less loss in the propulsion system,” Richman says. “More of the energy that goes into the battery goes into driving the vehicle, and gets to the wheels.”
- The average vehicle today is about nine percent aluminum
- Over 95 percent of the aluminum in a car is recovered, and can be recycled almost indefinitely
- Auto companies concentrated first on getting hybrid and electric powertrains perfected; they’re now working on weight reduction in the body
- Most of the energy in a gasoline engine is lost to friction and heat, and never gets to the wheels