Exploring Electric Vehicle Battery Life, Degradation, And Developments
A heated debate currently exists in the realm of battery life. EVs have not been in circulation long enough to gather comprehensive data on lifetime. However, a substantial indication may live in the warranties currently available from manufacturers. Tesla, for example, offers an 8-year warranty, the world’s best-selling Nissan Leaf with a 30kWh battery also provides an eight-year warranty period.
It is perhaps too early to estimate the actual life cycle of a lithium-ion battery, as the data just isn’t available. However, researchers at The Electrochemical Society found that partial discharge can increase battery life substantially. For example, a 100% discharge cycle (most aggressive), batteries can typically last between 300-500 cycles. However, take the discharge rate consistently to 50% and the life expectancy can improve considerably to 3 to 4 times.
Significant for consumers, charging habits are likely to dictate the cost of your EV over its lifetime.
To extrapolate the battery life to the EV lifetime, a key consideration to take into account over its internal combustion engine (ICE) competitor is the number of moving parts. A Tesla powertrain has 18 moving parts, whereas an ICE vehicle has hundreds.
Want more content like this? Subscribe to our newsletter and we’ll send it right to your inbox.
An implication of this is maintenance costs, while again studies are less than comprehensive, one can take a logical approach. The one substantial value of the EV is the replacement of a battery, essential to note the cost per kWh is declining all-the-time. According to a presentation delivered by the American Chemical Society, it is quite reasonable to estimate to the lifetime of a battery pack of an EV to be up to twenty years. And quote “That’s good news when you consider that some estimates put the average life expectancy of a new car at about eight years.” ICE vehicles have hundreds of ‘weak’ points. Timing belts are recommended to be replaced between 60 and 100k; other possible expenses include converter and transmission failures.
Battery degradation in electric vehicles leads to capacity fade, thereby shortening the vehicle’s possible range.
The lack of battery degradation data for analysis sparked Maarten Steinbuch and Merijn Coumans to create a study in the field. So, what they achieved was the first of its kind. Maarten Steinbuch and Merijn Coumans, in cooperation with the Dutch-Belgium Tesla Forum, created a public spreadsheet entitled ‘MaxRange Tesla Battery Survey’ that allows Tesla drivers to post information about their remaining battery capacity. You can participate via the Google Document.
The project began in 2015, as of 29th November 2017, 396 users where participating.
Data in Focus
The first graph looks at the impact of kilometers driven and how it reduces battery capacity. We can see that the majority of Tesla drivers have achieved up to 100,000km and had a maximum loss of 10% battery capacity/range. A few outliers, however, have driven more than 200,000km and still have up to 90% battery capacity left.