EV Battery Basics and How They Work
An electric battery is basically a device that stores chemical energy that is converted into electricity. The modern electric battery was invented by Italian physicist Alessandro Volta in 1800. This remarkable invention has enabled us to power much of our modern world with advanced devices such as laptops, smart phones, satellites, and even electric cars.
In this article, we’ll explore electric car battery basics including how they work and how to keep them running optimally.
How Long Do Electric Car Batteries Last?
The lithium-ion batteries in your electric car are designed for extended life. In fact, a new EVs battery pack will likely last longer than the car itself. However, electric car batteries will slowly begin to lose the amount of energy they can store over time. This phenomenon is called “battery degradation” and can result in reduced energy capacity, range, power, and overall efficiency.
Battery degradation is not easy to predict. Not all brands perform the same, and every vehicle is different in how it is driven, charged, and maintained. On the bright side, it’s not uncommon for modern EV batteries to last more than 10 years and some will go well beyond that before needing to be replaced. The average EV owner will sell their car long before they would need to replace the battery pack.
It’s important to note that battery degradation has been known to worsen if an EV battery is repeatedly driven down close to zero range and then is charged from low to full charge routinely, or if an EV battery is continually charged at Level 3, also known as DC Fast Charging (DCFC). Automakers suggest limiting DCFC use and not making it a primary source of charging.
Environmental factors, such as continued exposure to extreme temperatures, can impact battery performance as well, and may lead to degradation. Batteries don’t perform very well when the temperature is below 20 degrees Fahrenheit. When it’s really cold and you’re using the car’s heater, your range can temporarily drop by as much as 40%.
To maintain a battery pack at peak performance, it is recommended to keep EVs charged to between 60 and 80%, minimize fast charging and avoid extreme temperatures over long periods of time.
The Truth About Battery Degradation
Battery degradation doesn’t happen all at once. On average, electric car batteries lose only about one to two percent of their range per year depending on the factors discussed earlier. Fortunately, most batteries are designed for durability and will outlast the usable life of a vehicle.
If we look at the Tesla S model battery, researchers have found that traveling 500,000 miles on the original battery should not be a problem. Just because the battery degrades does not mean it is not drivable; it simply loses some of its range and charging efficiency.
In blog posts, Tesla model S owners have noted that approximately 95% of the battery retains its battery function during the first 50,000 miles. A 5% battery degradation could equal 20 miles of range. Oddly enough, the battery only degraded another 5% during the next 100,000 miles. So, 150,000 miles of active driving only resulted in a total average of 10% total battery degradation. Typically, you wouldn’t need to consider replacing your battery until degradation reaches around 65%.
Battery Warranties from Automakers
Currently, automakers have an 8-year or 100,000 miles warranty period on their electric car batteries. This is because federal regulation in the U.S. mandates that electric car batteries be covered for a minimum of eight years.
Before purchasing any vehicle, it’s best to check the warranty fine print. For example, the Nissan Leaf has a percentage guarantee of approximately 75%; however, they use their own measurement units represented in “bars.” A full Leaf battery has 12 bars, and the included battery warranty guarantees it for nine bars of charge.
What are Hybrid Batteries?
Hybrid car batteries are similar to EV batteries; they are simply smaller. Since the gasoline engine, electric motor, and battery work together in hybrids, if one is not performing optimally, it will impact the other.
Hybrid batteries typically last a vehicle’s lifetime, with modern vehicles routinely reaching 100,000 to 150,000 miles or much more. Accordingly, automakers usually offer a warranty for at least 80,000 miles. In most cases, you can expect to achieve over double that mileage without an issue. Some automakers such as Hyundai even offer lifetime warranties. As a result, if you’re the owner of a hybrid, you’ll likely never have to worry about replacing the battery.
There is also a time component to battery life — it degrades even if you don’t drive the car long distances. Hybrid batteries are designed to perform for at least 10 years. To cover any unexpected failure, time-based warranties are now standard in the industry. There is a federal mandate for warranties to cover eight years of hybrid car battery life, so most automakers offer warranties of eight years or more.
If you're faced with replacing a battery on an out-of-warranty car, there's no need to panic. The cost of a new battery pack continues to decline. Some technicians can even install an approved used battery pack salvaged from a wrecked vehicle, which would greatly reduce the potential repair cost.
Let's Talk About Range
Battery and range are linked. Generally, the bigger the battery pack, the longer the range. Of course, how you drive your EV affects range as well. Electric car technology is changing every day, but as of this writing, most EVs have a range of between 200 and 300 miles before they need to be recharged. Some vehicles, such as the Lucid Air claims a range of 406 to 516 miles depending on battery size.
Estimated range for all-electric vehicles continues to increase along with the number of new EVs hitting the road each day. Both battery range and EV adoption have increased rapidly over the last decade. As of around 2010, electric vehicles could barely go above 80 miles on a charge. In contrast, the recently announced Tesla Roadster, for instance, will have a range of over 600 miles!
The Million Mile Battery
As mentioned before, you may never need to replace your EV battery. As battery life keeps improving in newer cars, the issue of replacing the battery will become less and less important. In 2019, Tesla announced that it was working on a “million-mile battery” which would likely never need to be replaced.
After your old battery is removed from the vehicle, it usually enters a second life. Despite having less storage capacity, the battery can still serve a useful purpose. Old batteries are used in applications that are not nearly as taxing as powering a vehicle. For instance, a battery may be used for stationary storage to support your local utility company’s electric grid.
Afterlife of EV Batteries
As electric car adoption continues to gain momentum, used batteries pose a serious challenge to the environment. What do we do with all the discarded batteries? At the moment, there are two solutions: they can be recycled or repurposed.
Recycling must be handled properly, because toxic chemicals inside old batteries can lead to contamination of water and soil. As part of the recycling process, they are smelted to recover the lithium, cobalt, and nickel. However, this can be costly, so the repurposing of used batteries may be more cost-effective. Many EV batteries still have up to 70% of their capacity left, meaning they can be used for many other energy storage needs.
Automakers are exploring ways to profit from used batteries. In Japan, Nissan has repurposed batteries to power streetlights. In Paris, Renault has batteries backing up elevators. In Michigan, GM is using repurposed batteries from Chevy Volts to back up its data center. VW recently opened its electric car battery recycling plant in Germany that can recycle 3,600 battery systems per year. Repurposed EV batteries can also be useful for storing solar energy or running electric bikes and other tools. Finding new ways to turn these used batteries into productive solutions will benefit businesses, the environment, and consumers.