A new study conducted by researchers from Stanford University explored the lifespan of batteries in electric vehicles (EVs).
Overall, the researchers found that EV batteries can last a lot longer than many may have expected – as much as nearly 40% longer. This translates to significant savings for consumers, who won’t have to replace their batteries – or their cars – as often as they may have thought.
“We’ve not been testing EV batteries the right way,” said Simona Onori, senior author and an associate professor of energy science and engineering in the Stanford Doerr School of Sustainability.
“To our surprise, real driving with frequent acceleration, braking that charges the batteries a bit, stopping to pop into a store, and letting the batteries rest for hours at a time, helps batteries last longer than we had thought based on industry standard lab tests.”
A look at the study
The researchers explained that most tests that evaluate the longevity of EV batteries are done in labs, and they look solely at a consistent rate of change over time.
However, for consumers in the real world, this isn’t how they use their car batteries. Some days they’re in the car longer, some days they take several short trips, and some days they get stuck in unexpected traffic.
In this study, the researchers created three different profiles for over 90 different lithium-ion batteries to see which method of using the battery produced the best lifespan over two years. Ultimately, they learned that the more they mimicked the routines of everyday drivers, the longer the batteries lasted.
The researchers also looked at battery aging in two ways – batteries getting older because they’ve been in the cars longer, versus batteries getting older because they’ve been charged and recharged time and time again.
This test showed that EV drivers shouldn’t worry about wearing down their batteries from simply using and recharging them. Because the cars aren’t consistently in use, and there are regular starts and stops involved in daily driving, the time the batteries have been in the car is likely to be the biggest predictor of aging.
Moving forward, the researchers hope that these findings will make their way to EV manufacturers to ensure that consumers’ vehicles are equipped with the latest technology.
“Going forward, evaluating new battery chemistries and designs with realistic demand profiles will be really important,” said energy science and engineering postdoctoral scholar Le Xu.
“Researchers can now revisit presumed aging mechanisms at the chemistry, materials, and cell levels to deepen their understanding. This will facilitate the development of advanced control algorithms that optimize the use of existing commercial battery architectures.”