If you’re shopping for a new electric vehicle (EV), there may be several key features you’re looking for: trunk space, driving range, and other attractive styling options that may sway your decision for you. As more EV models come out and the technology improves, it’s possible that you’ll have a hard time comparing EVs on what’s probably a very important spec to you: charging speed. Truth be told, technical information about charging speed can be hard to understand. 

In this blog, we'll tell you all you need to know to compare EV charging speeds - information that will come in handy for your next road trip! 

How Charging Works: AC vs DC

First, let’s start with a technical explanation of how charging works. This section isn’t strictly need-to-know information. However, understanding this can be helpful to gain more insight into your EV.  

There are two types of vehicle charging: Alternating Current (AC) used for Level 1 and Level 2 and Direct Current (DC) used for fast charging.  

AC charging is a technical way to refer to what’s more commonly known as Level 1 and Level 2 charging. AC power is the power we get from regular household outlets and most power sources. AC power travels long distances without much energy loss, making it an efficient choice to run on electricity lines. However, for electricity to be used or stored in a lithium-ion (Li-ion) battery, it must be converted to DC.  (Understanding the difference between AC and DC isn’t that important; all you must know is that electricity must be converted to DC to power an EV.) 

To convert the electricity that comes from an AC wall-powered outlet to DC power, every EV contains a device called an “onboard charger.” (See the picture below.) In other words, Level 1 and Level 2 charging speeds are limited by how fast a car’s onboard charger can convert electricity from AC to DC.  

DC fast charging (or DCFC for short) can happen at much higher power and speeds because the electricity is, as the name suggests, already in DC format. So, DC fast charging stations can bypass the slow workings of the onboard charger.  

In the case of DCFC, a car’s battery management system (BMS in the diagram above) is the limiting factor for how fast the car can charge. The battery management system considers the battery’s state of charge, the ambient temperature, and other factors to allow the car to charge as fast as possible without overheating the battery and doing damage. Essentially, the battery management system is software that keeps the DCFC charging speed and battery health in fair balance.  

For Level 1, Level 2, and DCFC, charging speed can be measured according to power measured in kilowatts (kW). The higher the kW, the faster you charge.  

As EV technology improves, the maximum charging speeds of EVs are getting faster. This is where you might be interested as an EV shopper: if you care about charging as fast as possible, what should you be looking at to compare EV models? 

Level 2 

Level 2 is the most common charging speed relied on day-to-day by EV drivers. For many years, the standard for battery electric vehicles (BEVs) has been a charging rate of about 6-7.4 kW. Now it’s becoming more commonplace for new models to reach Level 2 speeds of 11 kW or even up to 19 kW.  Most importantly, level 2 charging will allow you to charge to most or 100% of your car’s range overnight. 

DCFC  

If you are trying to alleviate your range anxiety or want to buy an EV that will serve you best on long road trips, DCFC charging speed is probably the spec you want to focus on. There’s much more variability with DCFC speeds than there is with Level 2.  

The chart below is a generalized estimate of how many miles of range you can expect to gain in 30 minutes of charging.  

Clearly, the difference between 25 kW and 150 kW can mean hours of time.  

The values in the table above are generalized. There are many factors that can slow down DCFC charging speed, including: 

• State of charge. An EV will slow down its charging speed when it reaches 60% and significantly when it reaches 80%. 

• Temperature. DCFC is much slower in the cold than in moderate or warm temperatures. 

What’s more, there’s a huge range of DCFC speeds in new EVs, which can translate to big differences between cars that otherwise seem similar.  For example, though they have similar driving ranges, the Chevrolet Bolt has a 50 kW DCFC, whereas the Hyundai Kona has a maximum DCFC rate of 77 kW.  

On a long road trip, this could mean the difference between waiting 20 extra minutes at every charging stop! 

Another important factor is the range of the vehicle. Take a look at the Nissan LEAF and the Chevrolet Bolt; they have the same max charging rate, but because the Bolt has more range overall, it regains more miles and time going to 80% capacity than the LEAF.  

The final note about DCFC stations: EVs can only charge as fast as the stations they’re plugged into. You can’t use a 25 kW station and expect your car to charge at 150 kW. Always use a resource like PlugShare to identify the station’s power; although 150 kW is becoming the new norm, there are many DCFC stations that are much slower. (It’s important to consider the station’s power as well as the BMS. Here is more information on how BMS affects charging speed.) 

Summary & Car-by-Car Comparison 

If you’re shopping for a new EV and charging speed is important to you, what should you know, and what should you look out for? 

1. At Level 1, all EVs can charge at least 4 miles/hour using a regular household outlet. 
2. At Level 2, every EV will get a full charge (or almost full charge) if plugged in overnight. Variations in Level 2 charging speeds are small and likely not very noticeable for your day-to-day, though faster charging can be a nice bonus. 
3. If you care about charging fast, pay attention to the DCFC specs, range, and BMS. This is where you’ll see the most variability.

Here’s a chart of some of the most popular EVs and key specs about range and charging. For more information, check out the Drive Green EV Shopping Tool. 

*Trims vary by range, charging speed, and efficiency. We tried to compare base trims here, but confirm the specs if you’re at the dealership or ordering a car online.  

We hope this has cleared up the charging questions for you. If you're ready to continue on your car-buying journey, consider checking out the electric car shopping tool. If you're still waiting to buy a car, sign the pledge that your next car will be electric!