Kia

We've known for a while that modern EV batteries will easily go more than a decade without needing to be replaced, and when they do reach the end of their life cycle, almost 100% of the materials inside an EV battery pack can be recycled. If you've heard differently, you need to seriously reconsider where you get your information, because anyone still spreading outdated EV myths is probably wrong about a lot of other stuff, too. That said, there's a difference between not needing to replace a battery yet and the battery still being just as fresh as it was when it left the factory. So how much can you expect a modern EV battery to degrade over time? 

Sadly, as with most things in life, the answer is a little more complicated than we might like it to be. There's no hard and fast rule that says a battery that's X years old retains Y% of its original capacity. What's more, you'll see some variation between brands. For example, when the EV research company Recurrent looked at how much of an EV's original range was still available after three years, EVs from Cadillac, Hyundai, Mercedes-Benz, Mini, and Rivian all came in at 100%, Ford clocked in at 99.9%, Tesla at 96.3%, and both BMW and Jaguar rounded out the bottom at 90.8%. 

Those numbers don't necessarily mean the battery in the BMW EV degraded more over three years than the one in the Hyundai. Instead, we're seeing different automakers take different approaches to range estimates and battery life. Some prefer to offer as much as they can right out of the box and accept that the range will drop. Others build in a bit of a buffer and use software updates to keep range estimates more consistent. Because there's no escaping the fact that all batteries do degrade over time. 

On the S-curve

Rivian

The good news is that while batteries eventually wear out, they don't degrade at the same rate throughout their entire lifespans. Instead, total capacity drops off as you "wear in" the battery, then levels out for the vast majority of the battery's lifespan. Eventually, when it reaches the end-of-life stage, the rate of degradation increases again, but that shouldn't be an issue you have to worry about for a long time. As Recurrent noted:

Generally, lithium ion batteries degrade in an S-shaped curve. When a battery is new, there can be some noticeable degradation as the battery settles into its steady state. After that, there is a long period of slow, linear aging, followed by a sharp decrease when the battery dies. But even in cars that need a replacement, it is rare to see the catastrophic failure that is expected at the end of a lithium ion battery's life. Almost all of the EVs on the road today are in their stable state.

Warranties should also help assuage concerns over battery life. Not every battery warranty is the same, but typically, Recurrent says a standard 8 year/100,000-mile EV powertrain warranty guarantees your car will retain at least 70% of its original battery capacity, as well. So if you buy a new car with 300 miles of range today, come 2034, you can expect to still have 210 miles of range available. It could be even more range, depending on the battery, and especially if you charge your vehicle in a way that helps keep the battery healthy. 

Of course, no gas car would ever force you to put up with a powertrain that degrades over time, right? Wrong. Engine performance with internal-combustion-powered cars degrades over time, too. Engine degradation hurts power, too. Drive a 500-horsepower Ford Mustang Dark Horse 15,000 miles a year for eight years, and you'll likely lose between 49 hp and 88 hp in the process. Everything degrades with time, and when it comes to powertrains, it really is just a matter of picking your poison.