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Is Fast Charging Safe for your EV Battery?

Is Fast Charging Safe for your EV Battery?

By James Fisher

As electric vehicles (EVs) continue to gain popularity, so does the fear of range anxiety and concerns about battery life. Fast charging, also known as DC or Level 3 charging, has been a topic of discussion due to the belief that it degrades the battery significantly faster than AC charging. However, recent studies show that the effect of fast charging on battery health is very minor. In this article, we will discuss the reality of fast charging and its impact on your EV’s battery health.

What is Fast Charging?

Before we delve into the effects of fast charging on your EV’s battery, let’s understand what fast charging is. Fast charging stations can charge an EV in minutes, as opposed to hours with regular AC charging. These stations deliver between 7 and 50 times more power than an AC charging station. While the high power is great for topping up on the go, it generates considerable heat and can put the battery under stress.

The Impact of Fast Charging on Battery Health

Research shows that fast charging does decrease battery health more than AC charging, but the impact remains fairly small. Geotabs’ research from 2020 revealed that fast charging more than three times a month increased battery degradation by 0.1 percent compared to drivers who never used fast charging. Another study by the Idaho National Laboratory (INL) tested two pairs of Nissan Leafs charging twice daily over a year, with one pair using regular AC charging while the other exclusively used DC fast charging. After almost 85,000 kilometres (almost 53,000 miles) on the road, the pair solely charged using fast chargers lost 27 percent of their original capacity, while the AC charging pair lost 23 percent of their initial battery capacity.

The Advancements in Fast Charging

Most modern batteries are designed to be fast-charged and have integrated cooling systems to handle the higher power loads from fast charging. This is important not only for fast charging but also for extreme weather conditions, as your EV battery will suffer from very cold or very warm temperatures. Your EV’s battery operates optimally in a narrow range of temperatures between 25 and 45°C, and the cooling system allows your car to keep working and charging in low or high temperatures but might extend charging times if the temperature is outside the optimal range.

Best Practices for Charging in Relation to Battery Health

While occasional fast charging won’t harm your battery in any significant way, there are some best practices to consider when fast charging to ensure its impact on your battery will be as small as possible. For instance, you should avoid fast charging on extremely hot days or do it in the shade to prevent overheating the battery. You can charge in cold weather without harming the battery, but you should expect a slower charging rate and longer charging times as the car’s battery management system (BMS) reduces power to optimise charging and protect the battery. As a best practice with any Li-ion battery, keeping it between 20 and 80 percent charged is recommended, as extremely low or high states of charge can damage the battery over time.

Batteries Age Too

Just like us, EV batteries age with time and lose some of their capacity in the process. That said, the lost capacity is negligible, only about 2.3 percent per year, and is unlikely to impact your EV’s daily use or even be noticeable. While fast charging can increase the rate at which your battery loses capacity, its actual impact is only about 0.1 percent more capacity lost than without using fast charging.


Fast charging is a convenient solution for quickly topping up on the go, but regular AC charging adequately meets your day-to-day needs. With advancements in fast charging technology and EV batteries designed to be fast-charged, occasional fast charging won’t harm your battery in any significant way. However, to ensure its impact on your battery is as minimal as possible, you should follow the best practices for charging in relation to battery health. Overall, fast charging is a safe option for charging your EV, and with increasing infrastructure, EV adoption will continue to soar.

Written by James Fisher
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