Electric car batteries: how does their use affect them?

The fleet management and telematics company Geotab has published data detailing how the batteries used in electric vehicles degrade over time.

Geotab used data from 6,300 fleet and consumer electric vehicles worldwide and found that, on average, electric car batteries lose around 2.3 percent of their capacity per year, as reported by Quartz. Geotab says that at this rate, the majority of batteries will last longer than the lifespan of the vehicles they power.

The study further showed that the way a battery is cooled and/or heated by air or liquid can affect its longevity. In one comparison, the battery capacity of a 2015 Tesla Model S fell by an average of 2.3 percent each year, while the battery of a 2015 Nissan Leaf fell by an average of 4.2 percent this year. The Tesla Model S uses a liquid cooling system, whereas the Nissan relies on a passive air-cooling system.

Geotab also points out that battery degradation is not linear. As a result, a slow decline over many years may be followed by a sharp drop. Furthermore, several Tesla owners have said that the speed at which a battery can be charged may change over time as carmakers introduce over-the-air updates to protect the batteries, as Tesla has done in the past.

Electric car battery lifespan: does use make a difference?

Interestingly, the data showed that electric vehicles that are driven frequently do not experience more battery degradation than those that are not driven or charged as often. However, the location where an electric car is based does play a factor in battery longevity. Electric vehicles driven in warm climates degrade much faster than those in cooler climates. Frequent fast charging also accelerates battery degradation. You can click here to see the full study.

You may have noticed that it is difficult to get a direct answer to the question of battery lifespan. What you can find instead are statements that batteries are covered by warranty in case something goes wrong. Typically, battery coverage is 8 years / 100,000 kilometres, but this will vary by manufacturer and country.

What is reassuring is that battery costs are decreasing significantly year after year. This is true. Since 2010, the price of an average lithium-ion battery has fallen by more than 80%.A carmaker’s warranty on its battery technology and its promise of falling costs should inspire some confidence. However, wouldn’t it be much better to know how quickly your battery is expected to degrade and how to minimise this loss?