Will Level 3 Charging Degrade EV Batteries?
One of the most frequently cited concerns about Level 3, or DC fast charging, is that using fast chargers too much can damage an electric car’s battery, leading to a loss of battery capacity and range over time. Level 3 chargers push electricity into an EV battery much faster – more than 30 times faster in some cases – which in theory can stress battery cells and electronics. For potential EV owners who frequently take long trips and don’t want to wait hours for a charge, or for those who don’t have the ability to charge at home, the long-term impact of fast charging can be a concern.
Frequent Fast Charging Has Negligible Effect
Industry aggregator Recurrent, which tracks multiple data points across tens of thousands of EVs, recently conducted a study of over 12,000 vehicles in the U.S. to find out whether frequent fast charging has a big effect on battery capacity. Fortunately, the news seems to be positive. The battery management systems in modern EVs protect battery capacity and performance, and even frequent Level 3 charging has a negligible effect on range and battery capacity over time.
Recurrent’s study, which consisted largely of Tesla models, compared EV drivers that fast charge less than 10 percent of the time to drivers that use fast chargers at least 90 percent of the time – an extreme use case, as over 80 percent of EV charging typically happens on Level 2 chargers overnight. Their results show that the difference in range degradation over 2,000 battery days – over five years – was negligible, and not even statistically significant.
Modern EVs Good at Protecting Their Batteries
In fact, of 6,300 Tesla Model 3s tracked, vehicles that were rarely fast charged lost the same amount of range as those fast charged almost all the time. 4,400 Tesla Model Y SUVs were tracked over almost three years (the Model Y has not been on sale for as long as the Model S) and the results were similar. After 1,000 days, vehicles that were frequently fast charged actually lost slightly less range, though the difference was once again not statistically significant.
Recurrent says that its study findings were similar for other Tesla models, as well as for other EV manufacturers, though they are conducting more detailed research on newer vehicles for which long-term battery data is not yet available. But in short, the robust safety and battery management systems of modern EVs protect their batteries from damage from routine Level 3 charger use.
How Does Level 3 Charging Work?
It's worth explaining how Level 3 fast charging works, compared to the Level 2 charger you might use at home or at work. Electric car batteries run on DC (direct current) power. The electricity that comes from an outlet generally uses AC (alternating current). When using a Level 2 home charger, you’re using AC power, and your EV converts AC power to DC, which is then sent to the battery. The on-board charging equipment in an EV has a limit to how quickly it can convert the electricity – usually somewhere between 5 and 20 kW. That’s why Level 2 charging can generally add only about 20 to 40 miles per hour.
Level 3, or DC fast charging, bypasses the converter in the car. The conversion to DC happens outside of the car, in the charger. Because the on-board hardware in your EV doesn’t have to convert the current, Level 3 chargers can fill an EV battery much faster, usually taking less than an hour to fill the battery to 80 percent. Once your EV’s on-board electronics sense that this threshold has been achieved, the car automatically slows down how quickly it can receive a charge to protect the battery’s components. That’s why modern EVs seem to be able to protect their battery capacity even with regular fast charging.