How Long Do Electric Car Batteries Last?

With few exceptions, your electric vehicle (EV) battery is guaranteed to work significantly longer than an engine in a gas-powered car is, and in most cases, your battery will outlast the rest of your car's lifetime.

The warranty doesn't always line up with this reality. For electric vehicles, the federal government mandates that manufacturers issue the battery warranty at a minimum of eight years/80,000 miles. In California, that mandate is 10 years/150,000 miles. A few vehicles even offer unlimited-mile coverage on their batteries.

Estimating EV Battery Life

EVs haven't been on the road in large numbers for long enough to provide sufficient data on battery longevity. Of the 1.4 million electric cars sold in the United States since they were introduced in 2010, only around 400,000 are older than five years.

Battery efficiency and energy density also continue to improve on a regular basis. But the U.S. Department of Energy's National Renewable Energy Laboratory estimated in 2014 that EV batteries may last 12 to 15 years in moderate climates (or 8 to 12 years in extreme climates).

A lithium-ion battery stores lithium ions in separate parts of the battery called anodes and cathodes. A solution called an electrolyte carries positively charged ions from the anode to the cathode, creating the electric charge that runs into the circuits. The battery recharges when the flow of electrons moves—from the cathode to the anode.

The Use of Lithium-Ion Batteries

Electric vehicle batteries are most often lithium-ion batteries. They are lightweight and "energy dense," meaning they can carry much more energy per mass than other battery types. This has made them light enough to make electrified transport possible.

Lithium-ion battery prices have dropped by 97% since 1991 and continue to fall. Since the battery is the most expensive component in an EV, experts predict EVs will be cost-competitive with comparable gas-powered cars by 2025.

Lithium is the third lightest element on the periodic table, after hydrogen and helium. It has three electrons orbiting three protons with two electrons on its inner shell and one on its outer shell. That one outer electron, bound to the nucleus by electromagnetic force, can be knocked loose by a larger electromagnetic force, which creates a lithium ion with a positive charge (since electrons are negatively charged). The flow of those ions is what creates an electric charge.

An EV battery is a pack of individual battery cells, each about the size of a AA battery. They are bound together physically and electronically with circuitry and software to regulate the charging and discharging of energy.

Battery Degradation

Lithium-ion batteries do degrade over time, and the amount of energy they are able to store decreases. But battery degradation the range of the vehicle more than of its usability.

According to Electrek, at an average degradation rate of 2.3% per year, “the vast majority of batteries will outlast the usable life of the vehicle.”

Replacing EV Batteries

Replacing an EV battery is still more expensive than replacing a gas car's engine. Excluding labor, EV batteries can cost anywhere from $5,500 to $13,500.

However, since EV batteries are constructed out of many separate modules, it may not be necessary to replace the entire battery pack. The experts at Current Automotive note that they have encountered only one case where an entire Tesla battery needed replacing.

How to Maximize Your Battery Life

The main influence on battery lifespan is the number of cycles each battery cell goes through. So reducing battery consumption can extend the life of your battery, in addition to consuming less energy.

Here are some tips to improve the sustainability of your EV driving:

• Try to stay smooth. Quick starts and dramatic accelerations draw surges of power from the battery to the motor.
• Stay in the middle. Unless an upcoming road trip or commute requires a full charge, keep your battery charged between 20 and 80%, where the battery is at its most efficient.
• Avoid extremes. Temperatures between 60 and 80 degrees F are when EV batteries are at their most efficient. High humidity can also draw more power to batteries.
• Charge slow when possible. Fast-charging is convenient, but it reduces the long-term capacity of your battery.
• Plan your route ahead of time. If you need to charge while on the road, a good plan can help you avoid having to resort to fast-charging. Should you run out, only charge enough to get to your destination, then complete your charging upon arrival.