The differences between EV AC and DC charging

Electric vehicles need to charge their batteries as fuel-driven cars need to tank. As an EV owner, you can charge the battery with AC (alternating current) or DC (direct current). However, if you have been wondering what the differences between the two types of charging are and which one you should use, keep reading this article to find out.

What is EV AC charging?

Your electric car comes with an onboard charger whose function is to convert between alternating and direct currents. The conversion is necessary because the battery provides the current for the engine in DC. When you use AC to charge your car, the onboard charger converts the AC into DC before it charges the battery. The electricity from the grid is always AC. This was defined as a convention to reduce the impact of electrical accidents.

Most EV owners use AC charging because it is the easiest and least expensive. Level 1 and Level 2 chargers are powered by AC. The manufacturer usually supplies the former if you buy a new EV, but you must install your own Level 2 charging station.

What is EV DC charging?

Depending on the design, your electric car can bypass the onboard charger and directly send electricity to the battery. However, for this to happen, the AC must be converted into DC before it is supplied to the car.

This is where EV DC charging comes in. The charging station converts the AC into DC outside the car and then sends it directly to the battery. What makes the difference between AC and DC charging is where the conversion to DC takes place.

DC allows higher charging powers. Using the same power typically generates higher heat in the cables and charging systems when using AC. 

DC charging is often known as Level 3 and is usually available in public. Most times, they are offered by third-party companies that run them as a network, similar to filling station chains. You may be required to pay to use the chargers. Examples of DC charger networks include Electrify America, operated by Volkswagen, and Superchargers owned by Tesla.

DC chargers follow the CHAdeMO or CCS standards, but Tesla cars use proprietary charging tech.

Which is better for your electric car; AC or DC charging?

From the point of view of battery health, AC charging is better for your car. This is because DC charging is often done with high powers, heating up your battery, making it wear out faster. The temperature rises during DC charging, which fastens your battery’s degradation. It will steadily lose charge holding capacity, leading to declining driving ranges, until the battery is no longer suitable for use.

It is advisable to avoid relying on fast DC charging all the time to elongate your battery’s useful life. However, EV makers include many technologies and features to reduce the harmful effect of DC charging. There are home charging stations offering DC charging, compared to the public DC charging stations the power is a lot less, but compared to other home charging stations the power is pretty high. 

To reduce the impact of DC charging, some DC chargers switch to AC charging when the battery percentage reaches about 80 percent. 

DC chargers are often more costly and mostly need professional installation.

What is the main advantage of a DC charger over an AC charger?

DC charging is faster, meaning your battery gets ‘filled up’ faster. DC chargers or Level 3 chargers can utilize up to 480 volts, making charging speeds up to 250 kW possible. Using a DC charger, you can charge a typical EV battery to 100 percent in under one hour. In comparison, a Level 2 charger may take up to 8 hours to completely charge your battery on up to 2240 volts. Level 1 chargers are even slower as they may need up to 48 hours to charge your battery using 120 volts.

While a Level 2 charger can fully charge your car overnight, it is not always the practical option. For example, EVs on longer trips may need to make stops to replenish the battery before resuming their journey. This is why you are more likely to find DC chargers along interstate highways.

In the case mentioned above, DC charging is the obvious choice as you can add considerable driving ranges within 30 minutes. EV owners usually schedule other activities for the charging period. For instance, they could take a bathroom break or grab a bite while the car charges.

DC charging has a significant role to play in the adoption of EVs. Many potential EV users hold back because they entertain the fear of being stranded when they run out of battery while far from their home charger. However, more public chargers will gradually make the fear go away.

DC charging is the obvious choice when it comes to heavy-duty electric vehicles. These include electric public buses or trucks that require larger batteries to meet their power needs. Charger makers have been working on models capable of supplying megawatts instead of kW to reduce the charging times.

Conclusion

You can charge your EV with either AC or DC. The latter is significantly faster but can impact your battery negatively by exacerbating degradation leading to a gradual loss in driving range.