With the rise in popularity of electric vehicles, charging has become a hot topic. EV owners want to know how best to charge their vehicles to preserve battery health and still meet their daily driving needs. The two main options are slow charging and fast charging. Slow charging takes hours, while fast charging can provide a full charge in under an hour. But is it better to slow charge or fast charge your EV? There are pros and cons to both methods.
What is slow charging?
Slow charging, also known as Level 1 or Level 2 charging, operates on lower electrical currents and voltages. For Level 1 charging, a standard 120V household outlet is used along with the portable cordset that comes with the EV. This provides between 2 to 5 miles of range per hour of charging. Level 2 charging requires a 240V outlet, similar to what an electric dryer uses. Level 2 charging stations can recharge EVs in 4 to 10 hours, providing 10 to 25 miles of range per hour of charging.
The lower electrical current used in slow charging reduces stress and heat buildup in the battery. Slow charging is generally considered better for the long-term health of the battery. It keeps the battery cooler during charging, which helps it last longer. The one downside is that slow charging can take a very long time to fully recharge an empty EV battery.
Slow Charging Pros
- Gentler on the battery, supporting longer lifespan
- Charges at lower electrical currents and voltages
- Produces less heat in the battery
- Keeps batteries cooler during charging
- Can use a standard 120V household outlet for Level 1
Slow Charging Cons
- Very slow, can take 8+ hours to fully charge an empty battery
- Not practical for long trips or daily use if you drive a lot of miles
- Requires planning ahead to ensure vehicle is fully charged when needed
- Level 2 charging requires installation of a 240V charging station
What is fast charging?
Fast charging, also known as DC fast charging or Level 3 charging, operates at much higher voltages and electrical currents than slow charging. Special fast charging stations are required, which are often found at public places like shopping centers, rest stops, hotels, and workplaces. Fast charging can add 60 to 80 miles of range in just 20 minutes of charging. A full charge can be achieved in around 30 to 90 minutes.
The major advantage of fast charging is convenience. EV owners can quickly top up their charge when they’re on the go. Just a short fast charging session can provide enough power to complete a trip. However, there are some downsides. The high electrical currents generate more heat in the battery, which over time can degrade the electrodes inside lithium-ion battery cells. Fast charging too often may shorten the lifespan of a battery.
Fast Charging Pros
- Very fast, can provide 60+ miles of charge in 20 minutes
- Full charge can be achieved in 30-90 minutes
- Convenient for charging on road trips or when you need a quick boost
- Allows driving long distances with quick recharge stops
Fast Charging Cons
- Generates more heat in the battery which can degrade lifespan
- Excessive fast charging may reduce battery capacity over time
- Special charging stations required which are less common
- Can overheat batteries if used improperly
Is slow charging or fast charging better for your EV battery?
When it comes to maximizing battery lifespan, slow charging is generally better than fast charging. The lower electrical currents put less strain on the battery’s internal components. However, most modern EVs can handle some fast charging without major degradation issues. Here are some tips on how to strike a balance:
- Use slow charging whenever possible, such as charging overnight at home.
- Try not to let the battery dip below 20% if you can avoid it.
- Limit DC fast charging sessions to 1 or 2 times per week at moderate ambient temperatures.
- Avoid fast charging when battery is very hot or very cold.
- Newer EVs have battery cooling systems that reduce heat buildup.
- Don’t fast charge to 100% capacity; aim for 80% instead.
- Modern batteries hold up to fast charging better than early EVs.
Following those guidelines will allow you to fast charge when you need to while still preserving your EV’s battery capacity and longevity. Keep in mind that battery degradation will happen over time no matter what. Proper charging habits can help slow that degradation.
Other charging considerations
Beyond slow versus fast charging, there are some other factors to keep in mind:
Colder temperatures reduce a lithium-ion battery’s capacity and ability to charge quickly. Charging overnight in below-freezing temperatures will take longer. Hot temperatures also aren’t ideal and may affect charging speed. Try to avoid fast charging at temperature extremes when possible.
In general, try not to discharge your EV battery below 20% charge remaining. Deep discharges put more strain on the battery. Recharging from a low state of charge will take longer as well.
Battery cooling systems
Newer EVs have active liquid cooling that helps regulate battery temperatures during charging. This allows the batteries to handle occasional fast charging without overheating. EV models without active cooling need more care during fast charging sessions.
There’s no harm in leaving an EV plugged in after it reaches 100% charge. The onboard computer will stop charging once full capacity is reached. However, it’s best not to frequently charge to a full 100%. Try to time charging so the battery is at around 80% ahead of your next trip.
The verdict on slow charge vs fast charge
While slow charging is best for battery lifespan, today’s batteries and cooling systems allow for fast charging in moderation without major impact. Using a mix of slow charging at home and fast charging on the road is recommended. Just be mindful of environmental temperatures, charge levels, and not overdoing fast charging sessions. Employ smart charging habits and your EV battery can last many years and charging cycles.
Frequently Asked Questions
Is it bad to fast charge my EV every day?
Fast charging daily can degrade your EV’s battery faster over time. Frequent high-current charging adds strain and heat buildup. Try to limit fast charging to 1-2 times per week unless absolutely necessary. Slow charge at home whenever possible.
How many fast charges can an EV battery handle?
It depends on the model, but most modern EV batteries can handle 200-500 fast charge cycles before seeing significant capacity loss. Follow the automaker’s recommendations on fast charge frequency. Newer EVs with advanced thermal management can handle more fast charging.
What’s the cost difference between slow and fast charging?
Home slow charging costs around $0.04/kWh for Level 1 or $0.12/kWh for Level 2. Fast charging at public stations currently averages around $0.30/kWh. So fast charging is significantly more expensive than slow charging at home. But slow charging requires hours, so fast charging allows completing longer trips.
Should I charge to 100% before a road trip?
Most experts recommend against constantly charging to 100%, as this adds stress to the battery. Charge to 80-90% ahead of longer trips to provide a buffer. Then use fast charging on the road to top up as needed. Starting trips at a high state of charge reduces charging stops.
How can I prolong my EV battery’s lifespan?
Use slow charging whenever possible, avoid sustained high/low charge levels, limit DC fast charging frequency, avoid exposing your EV to temperature extremes, and follow the automaker’s charging recommendations. With proper care, an EV battery should last many years and charging cycles before needing replacement.
Slow charging is the best practice for optimizing EV battery lifespan, but occasional fast charging has become more viable thanks to improved engineering. Using both slow and fast charging judiciously allows you to maximize your driving range and convenience while still preserving your EV battery’s capacity over the long run. Following manufacturer guidelines, monitoring charge levels, and employing smart charging habits are key to getting the longest life from your vehicle’s battery.