It’s no secret that we are big fans of electric vehicles (EVs) here at Green Energy Consumers Alliance – they have lower operational costs over their lifetimes, and they are central in curbing greenhouse gas emissions in the transportation sector. Yet, many prospective EV buyers have not made the switch because of concerns about charging, especially when it comes to long-distance travel. While DC Fast Chargers have been deployed at unprecedented rates, some people are concerned about the impacts of fast charging on battery health. Below, we will dispel some of the most common concerns about DC Fast Charging and share some pointers for preserving your EV’s battery. 

How is DC Fast Charging Different from Level 1 and Level 2 Charging? 

DC Fast Charging stations deliver direct current (DC) power directly into the EV, charging the car’s battery. This is distinct from Level 1 and Level 2 charging, where the charging station is equipped with alternating current (AC) power, which is transferred into the EV and converted into DC power using the onboard charger. From here, the vehicle can use DC power to charge its battery. The point of DC fast charging is that it’s fast. How fast depends on the maximum power the vehicle can accept; a 2025 Lucid Air can add 200 miles in 17 minutes at 300 kW, for example, while a 2025 Chevrolet Equinox can add 77 miles in 10 minutes at 150 kW.

Visualization of DC Fast Charging

How could DC fast charging damage a battery? 

All batteries degrade over time. You can assess a battery’s level of degradation by measuring its state of health (SOH); i.e., how much of its original electric range is still available when fully charged. (For example, if an EV that originally got 200 miles per charge now only gets 190 miles per charge, its state of health would be 95%.) A vehicle’s battery capacity will change over time due to a myriad of factors, such as age, exposure to extreme temperatures, frequency of charge-to-discharge cycles (how often the battery is drained and then recharged), and the interior cooling system. Historically, experts have generally recommended DC fast charging as little as possible to keep the battery cool.  

Battery management systems in EVs are supposed to keep the vehicle battery in an optimal SOH by cooling the battery when it heats up during charging. These systems have dramatically improved over time, helping vehicles better manage the heat generated by DC Fast Charging. Now, new science suggests that DC Fast Charging does not cause as much long-term damage to EV batteries as previously thought. Two recent studies in particular are worth noting.

Recurrent: DC Fast Charging Does Not Cause Damage 

In a 2024 study of 13,000 2012-2023 Teslas, Recurrent, a company that shares insights on the latest EV battery research, found no statistically significant difference in the range of vehicles that were charged with a DC Fast Charger for more than 70% of charging sessions as opposed to vehicles that were charged with a DC Fast Charger for less than 30% of charging sessions. 

It is important to note that this study mostly consisted of recent models (2018-2023), so it remains unclear whether frequent DC Fast Charging would be more harmful towards older batteries. Furthermore, it is unclear to what extent these findings are generalizable and can be applied to other EV brands.  

Luckily, a recent Geotab study looks at many model years and brands. 

Geotab: DC Fast Charging Should Be Done in Moderation

A 2024 analysis on EV battery capacity by Geotab, a company developing fleet management software, found that the performance of EV batteries has generally improved from later to newer model years. They found that batteries, on average, only degrade by 1.8% every year, a significant improvement in comparison to an average degradation rate of 2.3% in 2019. At this rate, EVs could last for more than 20 years, saving vehicle owners $15,900 over their vehicle’s life due to low battery repair costs and avoiding maintenance tied to internal combustion engines, such as oil changes. 

The study noted that these results are dependent upon good vehicle health. That is, the vehicle battery ought to be kept between 20% and 80% state of charge, and owners should avoid frequent (more than three times a month) fast charging.  

Notably, Geotab found that there was no significant difference in the battery health of high-use vehicles than lower-use vehicles, meaning that frequent vehicle use, paired with frequent DC Fast Charging, does not cause significant battery degradation. Geotab did find that DC Fast Charging can be damaging when paired with high-temperature climates, which makes sense given that the DC Fast Charging process creates high battery temperatures, so additional heat from the external temperature will likely lead to battery damage. 

Geotab Taking Charge Report

This graph shows how the battery state of health changes over the course of four years in vehicles that are high-use in high-temperature climates and primarily charge using Level 2 ports. Over the first year, the vehicle's SOH decreases at a relatively similar rate among the varied DC Fast Charging frequencies. Beyond this first year of use, DC Fast Charging has a noticeable impact on SOH, with vehicles that DC Fast Charge 0-3 times per month having a SOH of 85% after four years of use (meaning if you fully charge the EV, it will only have a 85% of the range it had at the beginning of its life). Additionally, vehicles that DC Fast Charge more than three times per month have a SOH of 80%.  

BP Pulse Charging Stations in Boston

Key Takeaways

Overall, there is no need to worry about DC Fast Charging. It is entirely okay to use it when you need to. When you have a choice, it is best to opt for Level 2 Charging. Additionally, if you live in a particularly warm climate, it is important to be more sparing with DC Fast Charging. And regardless of whether you charge at Level 2 or DCFC, it’s best to keep the battery’s state of charge between 20 and 80 percent as often as possible. Don’t top it off except when you are going on long road trips.