What You Need to Know About Electric Car Battery Warranties

By · May 17, 2017


The Chevy Bolt’s battery warranty covers for eight years and 100,000 miles—and if its capacity drops by 40 percent.

Many electric car shoppers worry that buying an EV might mean replacing an expensive battery after a few years of use. Those worries are unfounded for a number of reasons. First, electric car batteries are manufactured to last the lifetime of the vehicle—with very few reported incidents of total battery failure. The more common (but still rare) occurrence is a significant reduction in range over time. Regardless, the key to putting your mind at ease is a better understanding of the warranties that come with all electric cars and plug-in hybrids.

The auto industry norm is to protect an electric care battery for eight years and 100,000 miles. (Hyundai goes further by offering a lifetime warranty on its plug-in car batteries.) But for EV batteries, it’s also important to make a distinction between warranties that not only cover total failure but also reduced capacity over time.

Like laptop or phone batteries, the amount of use—or the functional range, in the case of EVs—is slowly reduced over time. Most EV drivers will barely notice the reduction, but those who drive exceptionally long distances with regular full charge-discharge patterns, and those who live in hot climate climates, might experience a more dramatic reduction in range over time.

Covering Reduced Capacity

There are two camps as it relates to how the reduction of battery capacity is addressed in warranties. The first camp—which includes brands such as BMW, Chevrolet, Nissan and Volkswagen—provide protection that covers owners for specific levels of reduced battery capacity. The threshold for the amount of reduced capacity (or range) can be difficult to measure but is usually set in the warranty at 70 percent of the range compared to when the car was new.

In other words, when a fully charged electric car that is rated to provide 100 miles of range is only granting 70 miles per charge, it would be covered for replacement by the automaker. Of course, a car that only loses 10 percent of range over the warranty period would not be covered. (The Chevy Bolt is covered at the 60-percent level—or when the 238-mile EV can only provide 190 miles of driving range per charge.)

Again, we are talking about outlier cases. In the vast majority of cases, plug-in cars lose less than 10 percent of battery capacity even after 150,000 miles or more. EVs have sophisticated battery management systems that mitigate the damage that can come from the biggest threats: high temperatures and over-charging. Like all batteries, the cells in an electric car like to be babied with shorter lower-power charging times in cool weather.

The second camp specifically excludes capacity from its warranty. Those automakers include Fiat, Ford and Tesla. (Take note that Tesla’s warranty covers unlimited miles.)

Vehicles with longer range—like models from Tesla—are less likely to be frequently fully charged and discharged. As a result, they are less likely to experience reduced capacity over time. If the driver of a Model S starts the day with 300 miles of range and completes a typical 40-mile commute, then recharging to 300 miles is a minor event. But adding back 40 miles to a 100-mile EV represents a much deeper charging cycle. The relative impact becomes significant when you multiply these patterns over a few years.

Based on data collected by Plug In America, an EV advocacy group, the average Model S owner loses only 2.3 miles of range for every 10,000 miles driven. An estimated loss of 23 miles of range for every 100,000 miles is negligible.

The takeaway: it’s more important for EV buyers considering the purchase of a short-range EV to consider the battery warranty—and to choose one that covers you for reduced range over time. If you live in a very hot climate and have a long commute, pay even closer attention to the warranty. If that describes you, then you might be a candidate for leasing an EV for three years—a period in which these effects will have less impact and be fully covered during that time.

If you’re already experiencing a loss of range that you believe might one day exceed the warranty limits, call the automaker right away to create a case number that documents the current battery capacity. That will be useful in the unlikely chance that the range continues to drop and one day reaches a level qualifying for a replacement.

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