Tech Insights

Could EV Batteries Last 15 to 20 Years? Tesla Thinks So

May 09, 2023 by Kevin Clemens

Tesla’s latest report shows a 12 percent degradation in battery pack capacity over 200,000 miles.

The top three things most people buying an electric vehicle (EV) want to know are: How much does it cost? How far can it go on a charge? And how long will the battery last? The first one is easy, as the Manufacturer Suggested Retail Price (MSRP) and any local, state, and federal tax incentives tell you how much you will pay. Likewise, the range on a charge is provided by the Environmental Protection Agency (EPA) testing reported on the vehicle sticker. The last question of how long the EV’s battery will last is not so easy. 



Image used courtesy of Tesla

Factors Affecting Battery Life

How long the battery in an EV will last depends on a variety of things. For starters, any EV sold in the U.S. today has a battery warranty of at least eight years and 100,000 miles. The details are less clear. First, EVs are so new that few have been on the road for more than six years. Almost 30 percent of EVs on U.S. highways were sold in 2022. Of the EVs like some Tesla models and the Nissan Leaf that have been around for more than eight years, very few of the batteries have been replaced, implying that the lifetime of an EV battery, with proper care, could be more than ten and perhaps as much as 20 years.

Aside from recalls of the Chevrolet Bolt and Hyundai Kona to replace defective battery packs, replacement of the entire pack has been extremely rare. 



Another factor is degradation. Every time the lithium-ion battery in an EV is charged and discharged (considered one cycle), a tiny amount of its capacity to store electrical energy is lost. Lithium-ion batteries are capable of thousands of such cycles, and an EV owner will rarely discharge their car completely and then fully recharge it. Nevertheless, over time and with several charging cycles, the EV battery begins to degrade. 

Different car companies handle the degradation differently. Tesla, for example, guarantees that the Model 3 Standard Range battery will maintain at least 70 percent capacity for eight years or 100,000 miles, whichever comes first. The Model Y guarantees 70 percent capacity up to 120,000 miles, and the Model S and Model X guarantee the same 70 percent up to 150,000 miles or eight years. 

General Motors has an 8-year, 100,000-mile warranty but specifies that between 10 percent and 40 percent is possible for the warranty period. BMW and Volkswagen have eight years and 100,000 miles with 70 percent capacity.  Hyundai’s built in 2020 and beyond have a 10-year, 100,000-mile warranty at 70% capacity.


Tesla Impact Report

Tesla’s recently released Impact Report 2022 reports that its batteries (Model S and Model X only) degrade about 12 percent over 200,000 miles. The company’s previous Impact Report, released in 2021, indicated a 10 percent loss over 200,000 miles. 


Battery Charging Rate

Some different factors determine how much and how quickly a lithium-ion battery pack will degrade. Chief among these is the rate at which a battery is charged. Charging slowly, overnight, for example, while attached to a home charger, puts less stress on the battery materials, while DC Fast Charging at high voltages and currents degrades the battery more rapidly and creates heat within the battery, which is an enemy to the battery cells. The most effective way to increase battery life is to do most of the charging at home with a slow charger and use DC fast charging or Tesla supercharging only when traveling across the country or when it becomes absolutely necessary. 


Depth of Discharge

Another way that lithium-ion cells can degrade more rapidly depends upon how often they are fully discharged. The depth of discharge (DoD measures this and is a percent of the total [pack capacity discharged before the battery is recharged. If a 100-kilowatt (kW) battery is discharged by using up to 80 kW, for example, its DoD is 80 percent. Studies have indicated that a 50 percent DoD is optimum for reducing degradation. In addition, constantly charging a battery pack to 100 percent also degrades its performance more rapidly, as does discharging it below 20 percent. Unless long-distance travel requires a full battery capacity, it is better for battery life to keep between 20 and 80 percent, with a DoD of about 50 percent.


Size of the Battery Pack

If you are using only 50 percent of the pack capacity, then having a bigger pack can make it easier to travel longer distances or avoid recharging during the day. A larger-size battery pack can also still provide an acceptable EV range, even if the pack has degraded by up to 30 percent. For example, if your EV is capable of 300 miles when it is new and has degraded 30 percent in 8 years, it will still offer a 210-mile range, which might still allow the vehicle to be used as before. An EV with a smaller pack with a 200-mile range will only be able to travel 140 miles on a charge if it degrades 30 percent and may no longer be capable of fulfilling its owner’s goals. On the other hand, larger packs cost more to purchase, take longer to charge, and weigh more, using up consumables like tires and brakes more quickly.


EV battery packs

EV battery packs. Image used courtesy of Adobe Stock


Keep EVs Longer

Traditionally, gasoline-engine vehicles have a life somewhere around 200,000 to 250,000 miles before their complicated internal combustion engine fails in such a way that repairing the vehicle is no longer cost-effective. EVs, however, have a much simpler and more reliable drivetrain. A battery pack that no longer performs above 70 percent of its capacity can be changed for a new pack, one that could also incorporate innovations and performance improvements. This should be less expensive than purchasing an all-new vehicle, and it is possible the days of trading in an older car for a new one will soon be numbered. It’s a prospect that has traditional automakers, who for nearly a century have sold the public on the idea that they need a new car every three to five years, very worried.