Electric cars use two types of 'fuels': alternating current (AC) and direct current (DC) power. The power supplied by the grid is always AC, but electric vehicle (EV) batteries can only store power as DC. This is why most electronic devices include a converter in the plug. Whenever you charge a device, such as your smartphone, the plug converts AC power to DC without you even realizing it.
When it comes to electric vehicles, the converter is built inside the car. It's called the "onboard charger" though it really is a converter. It converts power from AC to DC and then feeds it into the car’s battery. This is the most common charging method for electric vehicles today and most chargers use AC power.
As we've learned, power from the grid is always AC. The key difference between AC and DC charging is where the AC power gets converted. In AC charging, the conversion happens inside the car, whereas in DC charging, the conversion occurs inside the charger. This means a DC charger can deliver power directly to the car's battery without relying on the car's onboard charger. DC chargers are larger and faster, representing an exciting breakthrough for electric vehicles.
Home EV chargers are always AC, with the most common home EV chargers being rated at 7.4 kW. Dedicated home chargers come in both untethered and tethered forms, compared to DC, which are only tethered. Charging an electric car at home with a 7kW takes approximately 4-8 hours with AC – however, this depends on numerous factors.
Most charging stations available today use AC charging, typically providing speeds of up to 22 kW, depending on your car and the power available from the charging infrastructure. AC charging is ideal for home or workplace use, where longer charging times are acceptable. In contrast, DC charging is more commonly found near highways or at public charging stations, where quick recharges are necessary. However, DC charging is beginning to appear in home charging setups, offering new possibilities for customers with its fast charging capabilities and the potential for bidirectional charging.
Technically, yes, you can have DC fast chargers installed at home, but it is not common. DC charging is typically found at public charging stations and motorway services due to the high cost of the equipment and installation, often referred to as ‘ultra-rapid’ and ‘rapid’ chargers. Not only are DC chargers expensive, but they also require a significant amount of power to operate.
Most EV owners opt for AC EV charging stations at home, typically at 7.4 kW. These are more affordable, easier to install, and won’t negatively impact your EV battery with daily use. Home EV chargers offer additional benefits, including convenience and cost savings compared to DC public chargers.
Higher-rated AC home chargers are also available at 11kW and 22kW for those interested in faster charging. However, these require a three-phase power supply, which is uncommon in UK households. Additionally, each EV has a maximum onboard charging capacity for AC, so your EV may not be able to utilize a 22kW rate, making the higher charging rate redundant.
When choosing between AC and DC EV charging, consider your charging needs, your vehicle’s capabilities, and the local charging infrastructure.
AC charging is ideal for home use due to its 7kW/22kW charging rate and lower installation costs. In contrast, DC charging is much faster, making it suitable for urgent charges, public charging stations, and long trips. However, frequent high-rate DC charging can lead to premature battery degradation and reduce your EV's range, making AC charging better for the battery's health.
Electric cars store DC energy, but chargers can use either Alternating Current (AC) or Direct Current (DC). Home EV chargers are generally AC, while public chargers can be either AC or DC. AC chargers draw alternating current from the grid and convert it to DC via the EV’s onboard converter. DC chargers, on the other hand, deliver direct current to the battery, resulting in faster charging. Due to their high installation costs, DC chargers are typically found at motorway service stations and public locations, whereas AC chargers are more common at homes and workplaces.
