The Real Duration Electric Car Batteries Keep Going: What You Need to Know

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• How Do Electric Car Batteries Work?
• How Many Years Does the Battery Last?
• What Happens to Old EV Batteries?

The lithium-ion battery packs in an electric vehicle (EV) may be akin to the one in your cell phone, but do they degrade as quickly? We take a look at how long an electric car’s battery really lasts.

Related: How Does an Electric Vehicle Work?

How Do Electric Car Batteries Work?

EV batteries are actually battery packs full of groups of individual lithium-ion cells, each of which can store a certain amount of power. As you drive around and use the car’s electrical systems, that stored energy is discharged until the battery needs to be topped up again.

The life of an EV battery is commonly measured in charge cycles -–that is, the number of times the battery is fully charged and discharged. As with other devices powered by lithium-ion cells, the amount of charge the battery can hold will decrease as the battery pack degrades over time. The battery in your smartphone, for example, might start to degrade after just a couple of years of use.

Thankfully EV batteries are built sturdier than that and the technology is constantly improving. Most car manufacturers have a five to eight-year warranty on their EV batteries. Tesla offers an eight-year warranty with unlimited mileage on the Model S, and Nissan backs their Leaf for eight years or 100,000 miles , whichever comes first.

An EV’s battery capacity is measured in kilowatt-hours (kWh). According to MyEV , the higher the rating, the better:

“An electric car’s battery capacity is expressed in terms of kilowatt-hours, which is abbreviated as kWh. More is better here. Choosing an EV with a higher kWh rating is like buying a car that comes with a larger gas tank in that you’ll be able to drive for more miles before needing a ‘fill up.’”

Pretty much all EVs are also built to keep their batteries from charging all the way to 100% or completely losing their charge. That helps extend the battery’s overall lifespan. Factors like extreme temperatures, driving at higher sustained speeds, and how much you use the car’s peripheral electronics will also affect how much you get out of each charge.

Lithium-ion batteries are lighter than the lead-acid batteries used in gas-powered cars, and are more energy-dense than rechargeable nickel-hydride batteries, making them the logical choice for powering an EV. Changes in the metal and chemical composition of these batteries in recent years mean we could see even higher energy capacity and shorter recharge times in future generations of EVs.

How Many Years Does the Battery Last?

Your individual driving habits will affect the lifespan of an EV’s battery, but most manufacturers cover their battery packs for at least eight years, and anywhere from 10,000 to 100,000 miles. Tesla and Hyundai cover their EV batteries for life. Read the fine print here, though—some manufacturers will only replace the battery in the event of complete failure, which is exceedingly rare.

So how long can you drive an EV before the battery starts to lose charge capacity? It varies by manufacturer and use conditions, but it’s usually a very gradual process. EV advocacy group Plug In America collects data from EV drivers on changes in charge capacity over time and found that Tesla Model S vehicles usually only lose around 5% of their total charge capacity after the first 50,000 miles of driving.

The bottom line? MyEV says that, when properly cared for, an EV’s battery should get you well past the 100,000-mile mark before its capacity is limited. Some estimates range as high as 200,000 miles. When driven around 12,000 miles per year, that’s around 17 years before the battery needs to be replaced . That’s somewhat less than the average mileage of 15,000 per year logged by drivers in North America but still promising.

Related: Level 1, Level 2, or Level 3? EV Chargers Explained

Some things will shorten your battery’s lifespan if done too often. Using fast charging stations all the time, for example, can burn out the battery faster because it’s receiving a lot of electricity very quickly. Extreme cold slows down the chemical reactions that take place in a lithium-ion battery and can affect capacity. Extreme heat can also reduce a battery’s charge capacity, but most EVs are equipped with a cooled battery back to mitigate that.

Conversely, steps like only charging the battery when necessary and staying between 20-80% capacity will help extend the life of an EV’s battery pack, according to EVBox .

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What Happens to Old EV Batteries?

EV manufacturers are working on ways to both repurpose and recycle old batteries once they’ve died or lost the capacity to power a vehicle. Completely dead batteries are usually recycled by being separated into their component metals, which are then used to rebuild new batteries. Only about half of a battery’s components can be recycled as of this writing, but new methods are being developed to glean more valuable metals from an EV’s battery at the end of its life.

Batteries with some capacity left can be repurposed to provide power in other ways. As backup batteries for homes, for example, or used to store energy from solar panels.