- A new study suggests that batteries in electric cars that regularly use fast chargers of more than 100 kilowatts degrade faster than those that rely primarily on slow charging.
- It is claimed that using fast chargers frequently can cause some packs to lose nearly a quarter of their capacity in eight years.
- We’ve seen other studies suggesting that fast charging has little impact on long-term battery health, so it’s not a settled debate.
America deploys public fast charging stations in… Recording speedwhere companies build ahead of demand and lay the foundation for an increasingly electric future. Stopping at these high-powered charging stations is undoubtedly convenient, helping drivers get back on the road quickly. But according to a new study, using them in certain ways could lead to unintended consequences on battery health and long-term deterioration.
Canada-based research company Geolocation The company analyzed more than 22,700 electric vehicles across 21 models and found that high-powered public fast-charging stations are the single largest contributor to accelerated battery aging. No, this does not automatically mean that fast charging is completely harmful to batteries. Instead, the study identified specific charging patterns where cells are exposed to much more stress than they would with slow charging.
BMW iX at Ionna Rechargery
Photography: Suvrat Kothari
The study shows that frequent use of Level 3 charging stations that deliver more than 100 kilowatts of power can result in twice the degradation rates compared to regular plugging into slower Level 2 charging stations or fast chargers that deliver less than 100 kilowatts of power. EVs that use fast chargers for less than 12% of their total charging sessions saw a 1.5% average deterioration per year. Those who fast-charged more than 12% of their total sessions saw a 2.5% annual decline.
The results got worse when owners used more than 100 kilowatt stations for more than 40% of their total charging sessions. They suffered a 3% annual decline. (Note, however, that batteries degrade fastest during their first two years, with the rate of degradation gradually decreasing over time.) Those who charged at speeds below 100 kW for less than 40% of their total charging sessions saw battery capacity decline by a modest 2.2% per year. In other words, the combination of high power and high frequency seems to be the most harmful to the health of the battery.
| DC FC frequency | group | Average annual decline |
| a little | Less than 12% of the total sessions | 1.5% |
| High | More than 12% of the total sessions | 2.5% |
| High frequency low power (<100 kW) | Less than 40% of the total sessions | 2.2% |
| High frequency power (>100 kW) | More than 40% of the total sessions | 3.0% |
Although this data is important to our understanding of long-term battery health, I would treat it with caution. For starters, charging behavior is just one variable of a very complex equation. Battery health is affected by everything from cell chemistry and manufacturer’s design choices to driving habits and climate. Extreme heat and cold can put stress on batteries, though almost all modern EVs now come equipped with heat pumps and advanced preconditioning and thermal management systems designed to keep packs operating within a safe temperature zone.
The study also contradicts another report by Battery Health and Data Frequent. After analyzing 13,000 Tesla cars in the United States, I found that there was no statistically significant difference in the range of electric cars that were quickly charged more often, versus those that relied more on slow charging. However, this study had a major caveat. The sample size of frequently fast-charging EVs was only 344, while that of infrequently fast-charging models was more than 13,000, making it difficult to reach a firm conclusion.
Photo by: Porsche
Geotab said in its study that the battery degradation rate in 2025 was 2.3% on average, meaning the average pack will have about 81.6% of its original capacity after eight years. This is up from 1.8% in 2023, but similar to 2020, when the decline also averaged 2.3% per year.
The company attributed the increase in deterioration from 2023 to 2025 to a growing network of high-power charging stations, which have now appeared throughout North America. Growth is particularly strong in the US with networks like Tesla Superchargers, Electrify America, ChargePoint, and Ionna, all of which are doubling down on their charger deployments despite… The expected cooling period for electric car sales After the $7,500 federal tax credit expires. Since high-power stations are more readily available to electric vehicle drivers, there will likely be an impact on long-term battery health as well, Geotab said.
The good news is that automakers and battery companies have known about this for a long time. Modern electric vehicles are equipped with in-package protections designed to slow deterioration regardless of charging method.
Electrify America’s leading indoor charging station in San Francisco, California.
To reduce stress on cells, battery management systems (BMS) automatically reduce charging speeds when the battery is almost full and lower speeds if the temperature becomes too high. Most automakers also recommend maintaining a state of charge between 10-80% for regular driving, since constantly storing a battery in a near-full or near-empty state of charge also accelerates battery aging.
For drivers who must regularly charge to 100% and run the battery for any operational reason — such as rideshare or delivery drivers — manufacturers typically build in buffers at both ends of the usable range. When your monitor reads 100%, there is usually unused capacity above this ceiling. The same is true for 0%, where a low buffer prevents the packet from entering a file Deep discharge conditionwhich may harm the battery. You and I will never see these margins in the real world, but they play a crucial role in protecting the battery.
For me, the takeaway is fairly obvious. If you’re interested in maintaining maximum range over eight to ten years, don’t overly rely on high-powered fast chargers when you don’t need to. Meanwhile, rest assured that frequent fast charging isn’t a death sentence for your high-voltage pack. A Tesla Model Y Premium with 357 miles of EPA range when new will still offer about 285 miles at 80% capacity after eight years. So it will remain very usable and worthy of a road trip for many years.
Unless you are constantly fast charging, day after day, using high-powered stations, severe degradation remains unlikely, Many other studies have concluded as well. It is also important to follow the manufacturer’s recommendations. Most users are wary of fast charging, and using fast chargers will not void your battery warranty. Since battery warranties in the US are a minimum of eight years and 100,000 miles, there’s not much to worry about. Use cheaper slow chargers when you can and don’t lose sleep over fast charging interruptions from time to time. Today’s electric vehicles are designed with enough guardrails to keep their batteries healthy for years.
Do you have any advice? Contact the author: suvrat.kothari@insideevs.com
