Difference Between AC and DC Charging

1. Location of Power Conversion:

There are two types of electricity transmitters for charging electric vehicles: Alternating Current (A.C.) and Direct Current (D.C.) power. The electricity grid gives A.C. power, but electric car batteries need D.C. power. The big difference between AC and DC charging is where the A.C. power changes to DC. It can happen outside or inside the car. DC chargers are usually bigger because the converter is in the charging station. This makes them faster than AC chargers at charging the battery.

On the other hand, if you use AC charging, the changing only starts inside the car. Electric cars have a built-in AC-DC converter called an “onboard charger” that changes AC power to DC power. After this, the car’s battery gets charged.

2. Home Charging with AC Chargers:

According to the theory and benefits of DC chargers over AC charger, one can install DC chargers at home, but there are better ideas than that.

DC chargers cost much more than AC chargers. They need more space and have complex parts, like active cooling. You also need a strong connection to the power grid. So, for home charging, an AC charger is a better choice. DC charging points are usually found along highways.

3. Mobile Charging with AC:

Only AC chargers can be moved, and there are two main reasons:

• Firstly, DC chargers have a very heavy power converter. So, carrying it on a trip is impossible. They are usually fixed in one place.
• Secondly, a DC charger needs a power input of 480+ volts. Even if it could move, finding a suitable power source in many places takes a lot of work. Most public EV charging stations offer AC charging, while DC chargers are mainly on highways.

4. Speed of Charging:

Another big difference is the speed of charging. DC chargers have a converter inside them. This means power from the DC charging station goes straight into the battery, skipping the car’s onboard charger. This makes charging with direct current ten times faster than charging with alternating current.

5. Charging Curve Shape:

Another important contrast between AC and DC charging is how their power output changes during a charging session, referred to as the EV charging curve.

• AC charging curve: When using AC charging, the power going to an EV follows a flat line rather than a curve. This happens because the onboard converter in the car is relatively small and can only handle a limited amount of power spread over a longer time.
• DC charging curve: On the other hand, DC charging delivers much higher power by bypassing the car’s slower onboard converter. However, its output creates a decreasing charging curve. This happens because the EV’s battery initially takes in a lot of power but gradually accepts less as it approaches total capacity.

6. Charging and Battery Health:

Deciding between a 30-minute and a 5-hour charging session might seem straightforward. However, it’s more complicated, especially if you’re not concerned about the cost difference between fast (DC) and regular (AC) charging.

Using a DC charger frequently can negatively impact the battery. This isn’t just a made-up story; it’s a real caution from some electric car manufacturers.

A study conducted by Geotab discovered that cars relying on rapid charging more than three times a month experienced a 10% increase in battery issues after 48 months. This was particularly noticeable in hot climates.

7. Cost of Charging:

One significant difference between AC and DC charging is the cost. AC chargers are more affordable than DC chargers. DC chargers have a higher initial cost and involve additional expenses for installation and connecting to the power grid.

If saving time is crucial, using a D.C. power point can be faster, even if it requires a higher payment. However, if you can charge your electric vehicle near your workplace, there’s usually no need to spend extra on super-fast charging. Home charging is the most economical choice, and investing in your charging station is cost-effective.