Quick Facts About Overcharging Electric Car Batteries
- Electric car manufacturers advise against regularly charging to 100% and recommend drivers stop charging when the battery reaches 80% capacity.
- Replacement battery packs are expensive — often costing several thousand dollars — but warranties provide at least eight years of coverage.
- Use fast charging stations sparingly and choose Level 2 charging for routine recharging.
Understanding the best practices for charging an electric vehicle is important if you’re a new owner or considering an EV as your next automobile. Even after learning about the car’s features and functions, you may still have questions about battery recharging. Can you leave it charging all night? Can you overcharge an EV? Are the batteries built to last? Below, we’ll answer these questions and dig a bit deeper into electric car battery technology.
- Overcharging Electric Car Batteries
- How Long Do EV Batteries Last?
- Tips to Prevent EV Battery Degradation
Overcharging Electric Car Batteries
Modern electric vehicles are designed with sophisticated battery management systems to prevent overheating and premature failure. These systems work, in part, by monitoring your charging sessions and sending alerts when you’ve reached the optimum capacity. Many DC (direct current) fast chargers automatically stop charging when the EV reaches 80% capacity. It’s not easy to quickly “top off” the battery like you would fill a gas tank, and it’s vital to avoid routinely hitting the 100% mark.
What Happens if You Leave Your EV on the Charger Too Long?
The battery stops charging when it reaches 100% if you leave your electric car connected to a Level 1 or Level 2 charger. If you’re using a fast charger that doesn’t stop the session at 80%, it will likely slow the charging current instead. These limitations are intentional. Safeguards like these help preserve the integrity of your battery.
How Long Do EV Batteries Last?
The lifespan of an EV battery will vary based on several factors. According to the National Renewable Energy Laboratory (NREL), today’s batteries typically last 12-15 years in temperate climates. Factory warranties extend coverage for at least eight years, with some automakers covering the battery for 10 years or longer. While the unit is guaranteed, your charging habits influence its longevity. For example, consistently charging to 100% and regularly discharging the battery to very low levels can lead to premature decline.
Replacement costs for EV batteries are a concern for many potential owners. The exact amount depends on the make, model, battery capacity, and parts availability. However, they can be costly — often several thousand dollars. As technologies continue to advance and economies of scale improve, prices for replacement batteries may become more affordable.
Tips to Prevent EV Battery Degradation
As an electric vehicle owner, there are several ways to prevent your battery from degrading prematurely.
80%/20% Rule for EV Batteries
Keep the charge level between 20% and 80% for optimal performance and longevity. Lithium-ion batteries degrade faster when frequently pushed to extremely high or low charge levels. Staying within this range will help minimize stress on the battery. It promotes a healthier, longer lifespan for your electric car’s power pack.
Avoid Fast Charging
Only use Level 3 DC fast chargers as needed. These charging stations provide a high-voltage flow of electricity straight to your battery. Level 2 chargers use alternating current to boost the battery at a slower pace. Speed is the primary advantage of fast chargers, but they generate more heat and stress on the battery. More strain on the battery encourages faster degradation. Slower charging methods may take longer, but they help maintain the battery’s health.
Don’t Drain Your Battery
Letting your battery reach 0% drains the unit of all its energy reserves. While we don’t recommend waiting to charge until your levels are below 20%, letting it die completely is worse. Most EVs will shut off before the battery completely discharges. Lithium-ion batteries have a limited number of charge cycles. Significant battery discharges promote degradation.
Stay Away From Extreme Temperatures
Extreme heat and cold can both have a negative impact. Newer EVs have systems that regulate the internal temperature of the batteries. Still, EV battery packs generally work best in temperate climates. On sweltering hot days, avoid parking under direct sun. Choose a garage or shaded area instead. Charge up at night or earlier in the morning before sunrise.
Additionally, cold weather can zap energy from your battery. Electric car drivers find extreme cold leads to longer charging times and shorter driving ranges.
Should You Leave Your EV Charging Overnight?
If you have a dedicated home charger, regularly charging your electric vehicle overnight can be a convenient way to keep the battery ready for your daily commute. Level 1 and Level 2 chargers commonly found in residential spaces have slower charging rates but can replenish most drivers’ daily miles overnight. If you follow the manufacturer’s guidelines for safe charging and storage, leaving it plugged in for long periods is generally considered a safe option. The car’s battery management system automatically stops the charging process when it’s complete.
Read Related Articles:
- Should I Charge My Electric Car Every Night?
- Do I Have to Pay to Charge My Electric Car?
- How Long Do Electric Car Batteries Last?
Editor’s Note: This article has been updated for accuracy since it was originally published. Chantel Wakefield contributed to this report.
