AC vs. DC charging of electric vehicles

The decision between AC and DC charging for electric vehicles is a central topic 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 will examine the differences between AC and DC charging, how they work and the effects on charging times, battery health and operating costs.

What is AC charging?

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

With an AC charging capacity of 22 kW, fully charging a Flux commercial vehicle takes about four hours.

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Advantages of AC charging:

• Protects the battery: The lower charging power is less stressful for the battery, which increases its lifespan.
• Cost-effective: Since the charging power is lower, AC charging is ideal for overnight charging. Off-peak electricity rates are often cheaper, which reduces operating costs.
• Widely used: AC charging stations are generally easier and cheaper to install, making them widespread 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 usually less powerful than external DC charging stations.

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What is DC charging?

DC (Direct Current) charging is the preferred method for fast charging electric vehicles. Here, the alternating current is converted into direct current in the charging station and fed directly into the battery. This allows significantly higher charging powers 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. A Flux commercial vehicle can achieve a range of 100 km in just 15 minutes with a charging power of 100 kW.
• Suitable for long distances: Thanks to fast charging stations along motorways and main roads, electric vehicles can be used for longer distances without any problems.

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Disadvantages of DC charging:

• Higher load on the battery: The high charging powers lead to greater heating and stress on the battery, which can reduce its lifespan and range in the long term.
• More expensive: Fast charging stations are more expensive to install and operate, which is also 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 maximise battery life and save costs.
• DC charging is ideal for situations where fast charging times are required, such as 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 – What 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 optimally utilise the advantages of both systems.

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