Fast charging is not a friend of electric car batteries

Every year, electric car batteries degrade. How much depends on factors only now being tested in the real world.

Some of the best data come from informal trials of electric vehicles (EVs) being conducted by fleet operators around the world. A detailed looked was supplied this week by the fleet-telematics company Geotab. It plumbed data from 6,300 fleet and consumer EVs to understand how their batteries were faring in the real world. It was a mixed bag.

The good news was that batteries last longer than many expected. On average, EV batteries lose about 2.3% per year—or 23 miles for an EV with a 200-mile range over five years. Geotab suggests at that rate most batteries will outlast the useable life of their vehicles (fleet owners often auction off their vehicles after 100,000 miles). Or it may change how long fleet owners retain their vehicles.