AC and DC charging, what's the difference?

Electric cars are on the rise becoming increasingly popular for both business and private use. Research has shown that in July 2019 a total of 2,461 electric cars were sold, which may have only accounted for just 1.1% of the new car market, however this number is a 62% increase on 2018's figures. A huge increase in just one year with sales set to rise further as more and more government incentives are released to support the adoption of EVs.

For efficient use of an electric car, a charging point at home is a must, especially if the electriccar in question has a lower range. After all, if you're driving longer distances the last thing you want is to be sat waiting at a public charging station before you can continue your journey. It's much easier to simply put your car on charge once you get home, after which you can leave the next morning with a fully charged battery for the day ahead.

When you have decided to have an EV charging point installed at your home, you need to then decide whether you wish to have an AC or DC charging station, but what is the difference and which charging station should you buy?

AC is the abbreviation for Alternating Current, which means that the current polarity constantly reverses, the voltage is positive one moment then negative the next. This change of direction occurs at extremely high speeds and is indicated by the Hertz (Hz) unit, which indicates how often per second that direction changes. The UK mains supply for electricity is around 230 volts at a frequency of 50Hz, which means it changes direction and back again 50 times per second.

When using an AC charging station, AC power is used from the charging station and then converted into DC power by the car.

DC is an abbreviation for Direct Current, which means that the current always flows in the same direction, from positive to negative. Many electronic devices require Direct Current, which is one of the reasons that many of these devices require a power supply or transformer. Batteries are a great example of a Direct Current, they always have one positive and one negative pole, the same as the battery in your electric car.

When using a DC charging station, DC power is used from the charging station which flows directly into the car's battery via the fast charging port of the car (CHAdeMO or CCS).

So now we know the difference between AC and DC charging stations, what does this actually mean when choosing a charging station? Quite simply, a charging station using DC power is much faster than an AC charging station as there is less resistance for the current of electricity. However, the disadvantage of DC is that it is much more expensive to install than an AC charging station. This is due to the fact that the charging station must be equipped with an inverter (to convert AC current from the power network into DC current) and in addition requires a much higher load from the power network.

At this point you may be wondering whether it makes more sense to buy a DC charging station. EVBox recommends choosing a DC charging station if your car needs to be fully charged within 20 minutes. With an AC charging station, this normally takes 4 to 8 hours.

However, it's not often that a car needs to be charged in such a short period of time. At home, electric cars are often connected in the evening and disconnected in the morning, whilst businesses usually do the opposite. In both cases the car is stationary and charging for several hours meaning a longer charge time isn't necessarily a negative thing. Due to the costs, AC chargers are much more popular and often a better choice for home use rather than DC chargers. DC chargers are most commonly found in places such as hotels and shopping centres where people prefer to charge much faster.

Note: Not all electric cars support DC power, so be sure to check this out if you are going to choose a DC charger.

Once you've made your choice on which charging station you would like, you will need to find an appropriately accredited installer to fit your EV charger. If you're still unsure about your situation and would like to speak to one of our energy experts then please feel free to contact us.