What is DC Fast Charging?


When considering electric vehicles (EVs), buyers often factor in charging speed, which can significantly affect their daily routines. Currently, there are three levels of charging speed for EVs: Level 1, Level 2, and Level 3, also known as DC fast charging (DCFC).

DCFC, the fastest of these three levels, is particularly useful for extended travel, where quick recharge stops are necessary. As EV ranges increase and charging infrastructure expands, DCFC could enable EV owners to take longer road trips more efficiently along American highways.

How DC Fast Charging Works?

Currently, three types of DC fast charging systems exist Combined Charging System (CCS), CHAdeMO (short for CHArge de MOve), and Tesla Supercharger.

Each of these systems employs its distinct charge port connector. The most prevalent option is CCS, although some automakers still adhere to the CHAdeMO standard. As per the EV Charging Rules, many DC charging stations support both CCS and CHAdeMO connectors from a single unit. It’s worth noting that Tesla Superchargers exclusively serve Tesla vehicles, but Tesla cars can also utilize CCS or CHAdeMO fast chargers with the aid of an adapter.

During the charging process, there exists a limit on the amount of power an electric vehicle (EV) battery can accept, denoted by the acceptance rate or maximum power rating, measured in kilowatts (kW). This rating varies considerably among different vehicle models. While numerous current EVs boast a 50 kW acceptance rate, newer models can accommodate charging speeds of up to 270 kW. As EV battery capacities have grown since the early days of EVs, DC chargers have also seen an increase in output capacity, with some now capable of delivering up to 350 kW.

Compatibility of DC Fast Chargers

Given the EV charging levels and wide range of power ratings for both EVs and their chargers, there may be concerns about compatibility. However, it’s important to clarify that the kW limits of the vehicle and the charger need not match. In other words, a 200 kW charger will function seamlessly with an EV that accepts 150 kW. The charger and the vehicle will engage in communication, and the charger will supply power at the rate the car can accept, which in this instance would be 150 kW. The vehicle’s battery management system is responsible for overseeing the charging process and allowing the vehicle to draw energy up to its maximum capacity.

The converse situation is similarly true. For instance, a vehicle with a maximum charge rate of 200 kW can use a 150 kW charger, but the vehicle will charge at a slower rate than its full capability, typically at 150 kW.

Once a vehicle’s battery charge surpasses 80%, the DC fast charging rate significantly diminishes to prevent overcharging the battery. Consequently, many EV manufacturers often specify the time required to fast-charge the battery to 80% capacity rather than reaching a full 100%.

Also See: What are EV Charging Basics?

What are Downsides of DC Fast Charging?

The downsides of DC Fast Charging:

1. Limited Infrastructure: DCFC charging stations (Level 3 chargers) are less widespread compared to Level 2 chargers, making them less accessible for EV owners.

2. Higher Costs: DCFC requires 480-volt electrical service, resulting in significantly higher installation and usage costs when compared to Level 2 charging. Additionally, DCFC charging typically comes at a premium rate per minute.

3. Potential Battery Degradation: Frequent use of DCFC may lead to thermal issues that could accelerate the degradation of an EV’s battery over time. While some automakers recommend avoiding daily reliance on DCFC, the precise impact on battery lifespan remains a subject of debate.

Must Read: 12 EV Charging Tips

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