AC vs DC Charging: What Are The Differences?
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AC vs DC Charging: What Are The Differences?

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What is the difference between AC and DC charging?



When it comes to charging an electric car, the terms AC (Alternating Current) and DC (Direct Current) often arise. These are two types of electricity, each with distinct characteristics, applications and advantages.

For EV owners, understanding the difference between AC and DC chargers is crucial for optimising their charging strategies, whether at home, work or on the go. This article explores the fundamentals of AC and DC charging, their practical applications and what they offer for electric car owners.

What does AC and DC stand for?



The distinction between AC and DC lies in how electricity flows. AC (Alternating Current) refers to electricity flowing in a sinusoidal pattern, reversing direction periodically. This type of electricity is supplied by power grids and used in home charging and businesses.

On the other hand, DC (Direct Current) flows in a single, constant direction and is the type of power stored and operated by batteries, including those in electric vehicles (EV).

The Role of AC and DC in EV Charging



Electric car batteries store DC power. The current from an AC source is converted to DC before it can be stored in the battery. This conversion process defines the key distinction between charging your car on AC versus DC:

• AC Charging: The conversion from AC to DC happens inside the car. An onboard charger within the EV handles this process, regulating the flow of electricity to protect the battery.

• DC Charging: The conversion occurs outside the vehicle, typically in a public charging station. Since DC power is supplied directly to the battery, this method bypasses the onboard charger and offers faster charging speeds.

AC Charging: Ideal for Home and Everyday Use



AC charging is the most common method for recharging EVs and is typically used for workplace and home charging solutions. When using an AC charger, electricity from the grid is converted to DC by the vehicle’s onboard charger.

Advantages of AC Charging



1. Widely Available: AC chargers are compatible with standard household electrical outlets and dedicated AC wall boxes.

2. Cost-Effective: AC chargers are generally more affordable to install and operate than DC fast chargers.

3. Gentler on Batteries: The slower charging speed is optimal for maintaining long-term battery health.

Limitations of AC Charging



Charging times are typically longer compared to DC fast charging. For example, charging a Kia EV3 GT-Line to 100% using an 11kW home AC charger can take 7 hours and 15 minutes, making it better suited for overnight charging. Charging overnight can also be scheduled via the Kia Connect app, maximising convenience.

DC Charging: Speed Meets Convenience



DC charging is primarily used in public charging stations where speed is a priority. With a DC charger, the power supplied is already in a format the battery can store, enabling ultra-fast charging. This is particularly beneficial for long-distance travel or when a quick recharge is needed.

To enable the fastest charging speeds, Kia electric cars have battery pre-conditioning. This feature prepares the battery for charging and enables the battery to charge faster. The on-board navigation system on Kia’s latest electric models also automatically starts the battery pre-conditioning if a charging station is selected as the destination.

Advantages of DC Charging



1. Rapid Charging Speeds: DC chargers can recharge a Kia electric car battery from 10% to 80% in as little as 18 minutes. *

2. Convenience on the Go: DC charging offers quick, efficient charging, making it perfect for public charging stations, enabling drivers to recharge rapidly while on the go.

3. Scalable Power Options: DC chargers offer power levels starting from 50 kW and scale up to high-power options exceeding 350 kW.

Limitations of DC Charging



• Higher Costs: The installation and operational costs for DC chargers tend to be higher, which may lead to increased pricing at public charging stations.

• Battery Health Concerns: Frequent use of DC fast charging can sometimes generate heat and strain the battery over time, potentially affecting its longevity.

FAQs

What does DC stand for?

Is a car battery AC or DC?

Are EV chargers AC or DC?

What is the difference between an AC and DC electric current?

 

Images shown are for illustration purposes only and may not be to full UK specification. Features shown are not standard across the Kia model range and availability will vary dependant on model. For further details please refer to the individual model specification sheets.

 

Product availability varies by models. To find out which products are available for your vehicle, please contact your Kia dealer.

 

*Maximum charging speed

In order to achieve the maximum charging speed, EV3 must be charged at an 400-volt electric vehicle charger that delivers at least 150kW of electricity. The acceleration time of 7.5 seconds corresponds to the standard range battery. In the case of the long-range battery, the acceleration time will be 7.7 seconds. 

The actual charging speed and charging time depend on battery temperature and weather conditions.