Like smartphone batteries, electric car batteries don’t last forever. Indeed, charge and discharge cycles cause chemical deterioration which gradually reduces storage capacity.
However, according to a group of researchers from the SLAC-Stanford Battery Research Center, it is possible that the rate of deterioration of electric car batteries is slower than those predicted by manufacturers. This discrepancy is believed to be due to a difference between how a battery’s longevity is tested in the laboratory, and how it will be used by consumers.
A difference between laboratory tests and real conditions
“Almost always, battery scientists and engineers have tested the lifespan of new battery designs in the laboratory using a constant discharge rate followed by recharging. They repeat this cycle quickly many times to quickly learn whether or not a new design is good in terms of life expectancy, among other qualities”explains an article from Stanford University.
But according to the new study, published in Nature Energy, that’s not a good way to predict battery life. Indeed, according to Simona Onori, lead author, real driving, with accelerations, braking that recharges the battery and stops, as well as rest times for the battery, would allow it to degrade less quickly (for example compared to estimates obtained in laboratories).
92 batteries tested for two years
To reach this conclusion, researchers at SLAC-Stanford Battery Research Center designed 4 different discharge profiles to test batteries. These profiles ranged from constant discharge to dynamic discharge which is supposed to simulate the discharge conditions of a battery in use on an electric car. In total, 92 lithium-ion batteries were tested, using the four profiles created, over two years.
Time would be the worst enemy of the battery
To the researchers’ surprise, the closer the profile was to real conditions, the higher the remaining battery capacity. They also discovered that accelerations, which correspond to a rapid discharge peak, do not promote battery degradation. Alexis Geslin, one of the three lead authors, also says that battery degradation due to time is greater than that caused by charging and discharging cycles.
“We battery engineers assumed that aging due to cycling was much more important than aging due to time. This is especially true for commercial electric vehicles, such as buses and delivery vans, which are almost always in use or recharging.”he explained, quoted by Stanford. “For consumers who use their EV to get to work, pick up their kids, go to the grocery store, but most of the time don’t use it or even charge it, the weather becomes the cause predominant part of aging in relation to cycles.”
- Work at SLAC-Stanford Battery Research Center suggests that the way battery life is tested does not match how they are used in real-world conditions
- Tests conducted by the authors of this study indicate that constant discharge and recharge cycles, used to test longevity, would degrade the battery faster compared to dynamic cycles that simulate use in real-world conditions.
- Therefore, your battery life may be longer than expected.
