In a recent study, scientists at the U.S. Department of Energy's Lawrence Berkeley National Laboratory (LBNL) say they quantitatively show that electric vehicles (EVs) will meet the daily travel needs of drivers longer than commonly assumed.
Many drivers and much prior literature on the retirement of EV batteries have assumed that EV batteries will be retired after the battery has lost 20% of its energy storage or power-delivery capability. The researchers say the study shows that the daily travel needs of drivers continue to be met well beyond these levels of battery degradation.
Samveg Saxena, who leads a vehicle powertrain research program at LBNL, analyzed real-world driving patterns and found that batteries that have lost 20% of their originally rated energy storage capacity can still meet the daily travel needs of more than 85% of U.S. drivers. He and his research team also analyzed battery power fade and found that even after substantial loss in battery power capabilities, performance requirements are still met.
“There are two main reasons people are hesitant to buy an EV: First, they're unsure it will satisfy their mobility needs, and second, they're afraid the battery won't last the whole life of the car and they'll have to replace it for a lot of money,” says Saxena. “We show that, even after substantial battery degradation, the daily travel needs of most people are still going to be met.”
“It is important to remember that the vast majority of people don't drive more than 40 miles per day on most days, and so they have plenty of reserve available to accommodate their normal daily trips even if they lose substantial amounts of battery capacity due to degradation,” adds Saxena.
As the battery continues to degrade down to 50% of its original energy storage capacity, the research found that the daily travel needs of more than 80% of U.S. drivers can still be met, and at 30% capacity, 55% of drivers still have their daily needs met.
“Even if a driver has a long, unexpected trip beyond the normal daily travel, an EV battery with substantial capacity fade can often still make the trip,” notes Saxena.
The researchers thus conclude that “range anxiety may be an overstated concern” since EVs can meet the daily travel needs of more than 85% of U.S. drivers even after losing 20% of their originally rated battery capacity. They also conclude that batteries can “satisfy daily mobility requirements for the full lifetime of an electric vehicle.”
The analysis of battery life was published online recently with open access in the Journal of Power Sources, “Quantifying EV battery end-of-life through analysis of travel needs with vehicle powertrain models,” which Saxena co-authored with Jason MacDonald of LBNL and Caroline Le Floch and Scott Moura of UC Berkeley.
More information is available here.