How long do electric vehicle battery packs last?

Research on EV batteries suggests the answer is different than you might think.

Comments Off on How long do electric vehicle battery packs last? April 10, 2013
by Design Engineering Staff

At the 245th National Meeting & Exposition of the American Chemical Society (ACS), scientists answered the question: How long before the expensive battery pack in my electric or hybrid vehicle dies?

According to Mikael Cugnet, Ph.D., a project manager specialist in Lead-acid and Lithium-ion batteries modeling and diagnostic at the French National Institute for Solar Energy (INES), the issue may not ultimately matter to the typical car buyer.

“The battery pack could be used during a quite reasonable period of time ranging from 5 to 20 years depending on many factors,” said Cugnet, who spoke at the ACS meeting. “That’s good news when you consider that some estimates put the average life expectancy of a new car at about eight years.”

To test the limits of lithium-ion EV batteries, Cugnet’s team reconstructed the experience of a typical EV battery packs and cells by simulating lifetimes of driving with cycles of draining and recharging. The researchers considered a battery “spent” once it lost 20 percent of its full power capacity.

According to Cugnet, an EV battery’s usable lifespan comes down to a few factors: temperature, state of charge and charge protocol. For example, battery performance begins to decline, he says, at temperatures above 86F.

“The higher the temperature, the lower the battery service life,” he said. “A temperature above 86 degrees affects the battery pack performance instantly and even permanently if it lasts many months like in Middle East countries.”

Cugnet also recommended that EV owners pay attention to how much their battery is charged, since a fully-charged battery is more vulnerable to losing power at temperatures above 86F.

The question of longevity matters to EV owners and manufacturers alike. The cost of the lithium-ion batteries that power these vehicles remains high, and an EV can cost twice as much as a gas or diesel equivalent. Customers want to make sure they get their money’s worth, and manufacturers are eager to demonstrate that EVs are economical.
www.acs.org