What Is DC Fast Charging?


DC Fast Charging (DCFC) is a high-power electric vehicle (EV) charging method that delivers direct current (DC) to an EV’s battery, bypassing the onboard charger.

This allows for a much faster charging speed compared to traditional Level 1 and Level 2 AC charging methods.

Two reasons that people didn’t change over to EVs in the past were the limited range and long charging times. The range is continually improving, but charging times remain an issue.

At a Glance:
1️⃣ DC Fast Charging (DCFC) reduces charging time considerably.

2️⃣ DC Fast Charging stations have a charging speed of up to twelve times faster than level 2 charging stations.

3️⃣ EVs should not use DC Fast Chargers permanently because they will degrade the electric vehicle’s battery.

4️⃣ DCFCs increase the time a vehicle can spend on the road, improving the cost/benefit formula.

To complement your understanding of what DC fast charging is, also consider learning about how DC fast charging works. Let’s begin!

How Does DC Fast Charging Work? 

All electrical current distributed by utilities worldwide is AC (alternating current). 

The car’s batteries store electricity as DC (direct current); therefore, before the AC power can be used, it must be converted to DC power. There are two options to achieve this:

  1. Convert the AC to DC within the car charging system.
  2. Convert the AC to DC outside of the car at the DC charging station.

Level 1 and level 2 EV charging systems input the current in AC, and the car’s rectifier converts it into DC. These are lower-powered devices that produce a current of up to 22kW.

DCFCs are big transformers that convert the AC current to DC outside the car. When the vehicle charging senses a DCFC system, it diverts the current from the internal charging system directly to the battery.

Put simply, DC fast charging bypasses the car’s charging system and sends the power straight to the battery.

Because the conversion from AC to DC happens outside the car (within the DCFC’s transformer), the power sent to that car can be as high as 350kW.

What Are The Benefits Of Using DC Fast Chargers?

Fast stations have two advantages over AC charging systems:

  1. The big, heavy rectifiers and related cooling systems needed to convert the large current to DC do not need to be in the EV. This results in space and weight gains.
  2. The DC current is more efficiently distributed to the car, reducing the time it takes to charge.

Faster Rate of Charge

Large DC chargers can recharge an EV up to 12 times faster than other types of electric vehicle charging.  

The actual charge times will be affected by the following:

  • EV’s battery capacity.
  • What level of charge it starts from.
  • The ambient temperature (the lower the temperature, the longer the charging time)
  • The charging capacity of the DCFC.
  • The charging rate is allowed by the car’s charging systems.

Convenience And Cost Savings

The time it takes to fill a gas-powered car’s gas tank compared to the time to charge an EV is often used to demonstrate that EVs are not as efficient.

This is true; however, increasing the range of EVs and reducing the charge times by using DCFSs reduces the effectiveness of this argument.

A vehicle’s purpose is to be on the road, and no one buys an EV because they enjoy charging the battery.

With commercial vehicles, it is a simple cost/benefit calculation.

The more the vehicle is utilized and the less time it takes to charge an EV, the higher the profit margins. DCFSs positively impact this calculation.

Types Of Electric Vehicles That Can Use DC Fast Charging

There are four types of electric vehicles:

  1. Battery Electric Vehicles other than Teslas
  2. Teslas
  3. Plug-In Hybrid Electric Vehicles 
  4. Hybrid Electric Vehicles

The charging requirements of each type of EV are as follows:

Vehicle TypeCharging OptionsCan Use Tesla Chargers?
Battery Electric VehiclesLevel 1, Level 2, DC Fast ChargersNo
TeslasAny station with supplied adapterYes
Plug-In Hybrid Electric VehiclesLevel 1, Level 2, DC Fast ChargersNo
Hybrid Electric VehiclesICE charges the electric motor’s batteryN/A

Which EV Models Can Use DCFC?

All EVs have DC batteries and can be charged by DCFCs. 

There are three EV charging connectors that fall under the DC category.

  1. CHAdeMO
  2. Combined Charging System (CCS)
  3. Tesla Supercharger

From the user’s perspective, the main difference is the car connector that is used. Understanding the CCS and CHAdeMO charging standards can further your comprehension of DC charging.

With Tesla recently agreeing to open the charging network to Non-Tesla vehicles, all EVs will be able to use any charger in America.

What Are The Drawbacks Of DCFC? 

There are two drawbacks to DCFC.

Possible Negative Effects On Battery Life

Many manufacturers recommend that DCFC systems be used infrequently, as charging your electric vehicle using DCFCs too frequently can significantly impact the lifespan of EV batteries.

The Idaho National Laboratory (INL) has found that an electric car’s battery will deteriorate slightly faster if DCFCs only charge it.

Limitations Of Charging Infrastructure 

There are often queues at DCFC facilities, and the EV driver must wait while the cars in front are charged. 

Key Takeaways

The benefits and limitations of DC fast charging are listed below.

1️⃣ DCFCs charge EVs and PHEVs substantially faster than AC chargers.

2️⃣ DCFCs should only be used infrequently.

3️⃣ The queues at DCFC charging stations can be problematic.

4️⃣ When Tesla opens up its charging network, the availability of DCFCs will improve.

The power of DCFCs is continually being upgraded. With the advances in battery chemistry, the future outlook of EVs and a reduction in charging times is very promising.

Next, I’d suggest broadening your knowledge by understanding EV charging in general, which includes DC fast charging.