AC / DC charging – What is the difference?

The legendary rock band AC/DC didn’t choose their name by chance—these bold letters stand for alternating current and direct current. No doubt, their music electrifies fans worldwide. But when it comes to EV charging, AC/DC plays an even more crucial role.

We’ll clarify what these terms mean and what you need to consider when choosing the right charging station for your electric vehicle.

What is AC/DC Charging?

AC (Alternating Current) refers to the type of electricity that comes from standard household sockets. In Germany, AC changes its polarity 50 times per second, meaning the current direction alternates continuously. DC (Direct Current), on the other hand, flows in only one direction, maintaining a constant polarity. This is why it’s also called direct voltage. Since batteries store energy in DC, AC power must first be converted into DC before an electric vehicle (EV) can charge. EVs can be charged using either AC or DC charging, each with its own advantages and considerations.

Types of Charging Stations

To charge quickly and efficiently, EVs rely on dedicated charging stations. These come in two main types:

• AC charging stations (standard charging) with a power output of up to 22 kW
• DC charging stations (fast charging) with a power output of 22 kW and above

AC charging stations supply alternating current (AC), which is then converted into direct current (DC) inside the vehicle.

DC charging stations have a built-in rectifier that converts AC into DC before supplying it directly to the EV’s battery. Since DC stations offer much higher power than a vehicle’s onboard charger, they enable significantly faster charging. However, fast charging typically comes with higher costs and is primarily used in public areas, such as motorway service stations.

When to choose AC or DC charging?

• DC charging is ideal for long-distance travel, where short charging stops are required.
• AC charging is well-suited for situations where vehicles are parked for at least 20 minutes.

AC Charging Stations

• Power output: Up to 22 kW
•  Supplies AC power
• Slower charging speed
• Lower costs
• Common in household sockets
• Best for parking durations of 20+ minutes

DC Charging Stations

• Power output: 22 kW and above
• Supplies direct DC power
• Faster charging speed
• Higher costs
• Common in public spaces, e.g., motorway stations
• Best for short stops

Overview: Pros and Cons of AC vs. DC Charging

AC Charging (Alternating Current)

✅ Advantages

• Availability: AC chargers are widely accessible and can be installed at home or in public spaces.
• Cost efficiency: AC chargers are generally more affordable to purchase and install compared to DC fast chargers.
• Versatility: Most EVs come equipped with an onboard AC charger, allowing them to charge via standard household sockets.

❌ Disadvantages

• Lower power output: AC chargers typically provide up to 22 kW, which is slower compared to DC charging.
• Longer charging times: Since AC must be converted into DC within the car, charging speed is limited by the onboard converter.

DC Charging (Direct Current)

✅ Advantages

• Faster charging speeds: DC chargers offer higher power output (from 22 kW and above), enabling rapid charging.
• Efficiency for long-distance travel: Ideal for quick top-ups during road trips.
• Direct energy transfer: Since batteries operate on DC, fast charging eliminates conversion losses inside the vehicle.

❌ Disadvantages

• Higher costs: DC charging stations are more expensive to install and operate.
• Less common: While DC fast chargers are increasing, they remain less widespread than AC stations.
• Potential battery strain: High-power fast charging can stress the battery over time, potentially leading to faster degradation.

Which Plug Types Work with AC and DC Charging?

AC charging stations (standard chargers) are compatible with:

• Household plugs (Schuko)
• CEE plugs
• Type 1 & Type 2 connectors

DC fast charging stations require special EV charging cables, typically using:

• CHAdeMO
• CCS (Combined Charging System)
• Tesla Supercharger