2023-07-07

Will DC Fast Charging Reduce Your EV’s Battery Life?

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What is fast charging?

Fast charging, also referred to as Level 3 charging, is a type of electric vehicle (EV) charging that allows for rapid charging of an EV battery. This is made possible through the use of direct current (DC) rather than alternating current (AC) used in Level 1 and Level 2 charging. DC fast charging stations usually provide high-power charging rates, which can vary depending on the station and the EV model.

Compared to Level 2 AC charging, which can take several hours to fully charge an EV battery, DC fast charging can charge an EV battery up to 80% in as little as 30 minutes. This makes it a convenient option for long-distance travel or when a quick charge is needed.

The Idaho National Laboratory (INL) conducted a study on two pairs of Nissan Leafs that were driven and charged twice a day. One pair was charged using Level 2 AC chargers at 240 volts, similar to those found in private homes, while the other pair was charged with direct current at a Level 3 station. Both pairs traveled the same distance along the same route for a year and were tested under the same conditions. The climate control systems were set to the same temperature, and all four cars were driven by the same team of drivers. The battery capacity of the cars was tested at 10,000-mile intervals.

After driving all four test cars for 50,000 miles, the pair that was solely charged using fast chargers lost 27 percent of their original capacity, while the pair that used AC charging lost 23 percent of their initial battery capacity. These numbers represent a difference of only 3 miles in range without recharging, given that the Nissan Leaf had an average range of 73 miles.

However, it is important to remember that battery technology continues to improve. It’s hard to say whether the results of all this testing hold true against the wonderful innovation coming out of the electric car companies.

The advancements in fast charging

Automakers employ various thermal management systems to regulate battery temperature and prevent heat buildup, which can damage the battery and reduce its lifespan. Some use active air cooling, which utilizes air conditioning technology to keep the battery cool with cold airflow. Others, like Tesla, use liquid coolant to prevent heat buildup in critical areas. These measures help preserve battery health and prolong the life of the car.

Tesla has claimed that its batteries retain over 90% of their capacity even after driving 200,000 miles. However, some older cars rely on passive air cooling, which is less efficient at removing excess heat and is being phased out in favor of active cooling systems. The Nissan Leaf is a prime example of a car with a passive cooling system, but even the upcoming Nissan Ariya will feature liquid-cooled thermal management.

In short, the effect of fast charging on battery health depends on the type of car and thermal management system employed by the manufacturer.

So should you fast charge your EV?

For the majority of EV owners, fast charging their EV battery on a regular basis is not harmful. As long as your EV has active battery cooling, which is now commonly included in many EV models, it will not negatively impact the long-term health of your car’s battery.

On the other hand, public chargers are operated by third-party companies that aim to make a profit, which often results in higher charging costs. Therefore, we only use fast charging to charge electric vehicles when traveling or in emergencies. At other times, we can charge at home charging piles.

Best practices for charging in relation to battery health

Maintaining optimal battery health is crucial for electric vehicle (EV) owners, and following recommended charging practices is key. Here are some best practices to keep in mind:

Charge at moderate rates

Charging your EV’s battery to its maximum capacity on a regular basis can accelerate battery aging. To extend battery life, aim to keep the state of charge (SoC) between 20% and 80%. Some EVs have “optimized charging” options that automatically regulate charging levels to improve battery longevity.