How the battery of an electric car degrades and how to extend its useful life

One of the most delicate aspects of electric cars is the condition of their batteries. This essential component is responsible for storing the electricity that powers the electric motor, and it is vital that it remains in good condition and performs its function efficiently throughout its entire useful life. But we know that batteries, whether in cars or mobile devices, lose effectiveness over time.

In the case of battery electric and plug-in hybrid cars, this is an area being worked on, and all research needs, first and foremost, information. Understanding the lifespan of batteries and their rate of degradation is important for improving the process of storing electricity and preventing these losses in efficiency.

Most of the data is obtained unofficially, from information provided by electric vehicle fleets in service. The owners of these electric car fleets have been gathering information for years, and there are companies that compile it and allow these data to be well understood in order to improve batteries.

Longer useful life

It is important to know that the average lifespan of batteries has increased. The technology applied to today’s batteries allows them to deliver more capacity for longer. According to data compiled by the fleet telematics company Geotab, electric car batteries lose 2.3% of their storage capacity per year. In practical terms, this represents a range of 37 kilometres less after five years in a car with a range of 320 km.

This data suggests that batteries would last longer than the useful life of the car, although with some loss of capacity. There are fleets of Tesla that have managed to operate for 330,000 kilometres on the same battery, and after that period of use they had lost 23% of their capacity. That is, from 418 to 320 kilometres of range, almost 100 km.

How fast charging affects it

Frequent charging does not appear to have a very marked effect on the loss of battery capacity, but other variables such as temperature and the use of direct current for charging do. The degradation of the battery can be accelerated in warmer places, and in addition, the use of fast chargers, which use direct current for charging, worsens the situation.

When this direct current technology is used, degradation is 10% over six years, higher than the degradation that occurs when slow charging with 120 or 240 volt alternating current is performed. Another point to consider: degradation is not linear.

This means there may be a slight degradation during the first years and suddenly, once a certain number of years of use is reached, a rapid degradation can occur. For this reason, Geotab recommends charging the electric car battery with a slow charging system. They also recommend keeping the battery charge between 20 and 80%.

This will not stop the loss of battery capacity, but it will extend its useful life. Nevertheless, the current generation of electric cars is barely ten years old, so many more data still need to be collected on battery performance and lifespan under real driving conditions.