Hesitation about buying a new EV is fading. Seventy percent of Americans identify electric cars as the future and 30% are considering one for a future purchase, according to a recent Consumer Reports survey.
But Washingtonians still have a lot of questions about used EVs and their batteries.
While an internal combustion engine has 2,000 moving parts, an electric motor has only two dozen. The most important, and expensive, part of an EV is the battery, and it’s literally a black box. That is what I am trying to change with better transparency around battery health and actual EV range.
My company, Recurrent, has been studying thousands of electric cars and their batteries and these are the questions I hear most often from drivers when they are considering a used EV:
- What is the actual, real-world battery range?
- How does battery range change in different conditions, like summer or winter?
- And what will the range be in 1, 2, 3 years from now?
Here are the things that I have learned by researching 5,000 electric cars across the US. If you’re intrigued, I invite you to get in touch or register your EV in our battery study to get monthly battery reports.
Lesson 1: Batteries degrade over time
Like your cell phone or laptop battery, an electric car battery will degrade over time. This degradation happens in two ways: a) naturally as the battery ages, and b) based on the way it is used, charged and stored. The first sort is called calendar aging and, like human aging, there is nothing we can do to stop it. The way that a battery is used, stored and charged, which we’ll explain in lessons 2 and 3, can accelerate calendar ageing.
Lesson 2: Temperature affects short-term range
The Pacific Northwest is a great place to own an EV because electricity is cheaper and cleaner compared to many other places in the country, gasoline is expensive, and our climate is temperate. We know that extreme temperatures have a pronounced effect on battery health and performance because they change the rate of chemical reactions that make the battery work. While cold weather causes temporary reductions in battery efficiency, and how far your car can go on a single charge, it has no long lasting effects on the health of your car battery. Heat, on the other hand, can speed up degradation and corrosion processes in an electric vehicle. While an occasional scorcher likely won’t fry your battery, we do recommend that drivers find a shady parking spot or climate controlled garage for optimal long-term battery health.
This chart sheds light on how EV ranges are affected by temperature. In the Chevy Bolt, for example, we can see that range decreases as outdoor temperatures move away from 70 degrees Fahrenheit. Check out these guides for more detailed information about Tesla Model 3 and Chevy Bolt batteries.
Lesson 3: Charging behavior affects long-term range
The other major influence an EV driver can have on their battery health is to avoid very high and very low states of charge. Sometimes it is necessary to charge to 100%, but most daily drivers find they can keep their state of charge between 30% and 80% with plenty of range to spare. If you’re leaving town or don’t use your car every day, try to store it with the battery as close to 50% charged as possible. This is the most balanced chemical state for the battery and best delays the natural aging and degradation processes.
Finally, despite all this advice, remember that your electric car battery is much more robust than the battery in your cellphone or laptop. Electric vehicles are built to be used and enjoyed, so take these recommendations as best practices, but not strict requirements.
–Written by Scott Case, CEO, Recurrent