Here’s one way we know that an EV’s battery will last the car’s lifetime

Enlarge / An EV's battery represents as much as 25 percent of the cost of the car, so it's understandable that people are nervous about longevity. (credit: Aranga87/Getty Images)

It's often said that the easiest way to get people to buy an electric vehicle is to let them test-drive one. But here in the US, EVs only accounted for 3 percent of the 15 million new vehicles sold in 2021. That means there are an awful lot of misconceptions out there when it comes to these newfangled machines.

The top concern is probably range anxiety, a fear that is usually dispelled as someone gets used to waking up to a full battery every morning. I won't dwell on that today, but the next-most common point of confusion about EVs has to be the traction battery's longevity, or potential lack thereof.

It's an understandable concern; many of us are used to using consumer electronic devices powered by rechargable batteries that develop what's known as "memory." The effect is caused by repeatedly charging a cell before it has been fully depleted, resulting in the cell "forgetting" that it can deplete itself further. The lithium-ion cells used by EVs aren't really affected by the memory effect, but they can degrade storage capacity if subjected to too many fast charges or if their thermal management isn't taken seriously.