AC vs. DC charging of electric vehicles

The decision between AC and DC charging for electric vehicles is a key issue for drivers and fleet operators. Both methods have specific advantages and disadvantages that should be considered depending on the usage scenario. In this article, we look at the differences between AC and DC charging, how they work and the impact on charging times, battery health and operating costs.

What is AC charging?

AC charging (alternating current) is the standard method for charging electric vehicles. The alternating current is taken directly from the power grid and converted into direct current in the vehicle to charge the battery. This is done via an inverter integrated in the vehicle.

With an AC charging capacity of 22 kW, it takes around four hours to fully charge a Flux commercial vehicle.

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Advantages of AC charging:

• Gentle on the battery: The lower charging power is less stressful for the battery, which increases its service life.
• Cost efficiency: As the charging power is lower, AC charging is ideal for overnight charging. Night-time electricity tariffs are often cheaper, which reduces operating costs.
• Widespread: AC charging stations are generally easier and less expensive to install, making them widely available in urban and rural areas.

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Disadvantages of AC charging:

• Longer charging times: Due to the lower charging power, it can take several hours to fully charge the battery.
• Limited charging speed: The charging speed depends on the capacity of the integrated inverter in the vehicle, which is generally less powerful than external DC charging stations.

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What is DC charging?

DC charging (direct current) is the preferred method for fast charging electric vehicles. Here, the alternating current is converted into direct current at the charging station and fed directly into the battery. This enables significantly higher charging capacities and shorter charging times.

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Advantages of DC charging:

• Fast charging times: Thanks to the high charging power, the battery of an electric vehicle can be charged in a very short time. With a charging power of 100 kW, a Flux commercial vehicle can achieve a range of 100 km in just 15 minutes.
• Long-distance suitability: Thanks to fast charging stations along highways and main traffic routes, electric vehicles can easily be used for longer distances.

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Disadvantages of DC charging:

• Higher load on the battery: The high charging power leads to increased heating and load on the battery, which can reduce its service life and range in the long term.
• More cost-intensive: Fast charging stations are more expensive to install and operate, which can also be reflected in the higher charging fees.

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When should AC and when should DC charging be used?

The choice between AC and DC charging should be based on individual requirements:

• AC charging is ideal for regular, gentle charging overnight or during longer downtimes to maximize battery life and save costs.
• DC charging is ideal for situations where fast charging times are required, for example on long journeys or in commercial use, where vehicles need to be ready for use again quickly.

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Conclusion: AC vs. DC - Which is better?

There is no clear "better" when choosing between AC and DC, but it depends heavily on the usage requirements. While AC charging offers a cost-effective and battery-friendly method for everyday use, DC charging is essential for users who rely on fast charging times and long ranges. A smart combination of both charging methods can help to make the most of the advantages of both systems.

Through careful planning and understanding the respective pros and cons of AC vs. DC, drivers and fleet operators can increase the efficiency of their charging process, reduce operating costs and maximize the lifespan of their vehicles.