How can an electric vehicle battery be charged at home? How can charging costs be minimized? Why isn’t connecting directly to a home outlet the best solution? What is the difference between public AC and DC chargers? Why shouldn’t you always use fast DC chargers for your electric vehicle battery?
Electric vehicles (EVs) are increasingly becoming part of our daily lives. Their batteries can be charged in various ways, including at home. However, the different charging methods can often cause confusion.
The main issue with charging EV batteries is that the city power grid supplies alternating current (AC), while an EV battery requires direct current (DC). This means a converter is needed to change AC to DC for charging the battery.
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All modern EVs come equipped with AC-to-DC converters, allowing them to be charged using the city’s electrical grid. However, these converters would need to be quite heavy to be powerful enough, making integrated charging relatively slow.
Charging Through a Home Outlet
Charging via a home electrical outlet is the most common and accessible method for anyone with a house or garage. The maximum power you can get from an outlet is 3.6 kW. For some EV models, this charging power can be reduced to 2.2 kW if the installations are old.
This makes it the slowest method of charging an EV battery. However, despite its slow speed, charging an EV via a home outlet is sufficient for most needs. Depending on the vehicle, charging overnight can provide enough power for about 120 miles, which is more than enough for the average driver’s daily needs. Charging at night in Serbia is also cost-effective due to lower electricity tariffs during this time.
Home-installed Chargers
Charging an EV battery via a home charger is a good solution if you drive long distances daily or need faster home charging for any reason. A home charger can provide up to 22 kW, significantly faster than a home outlet.
Before purchasing and installing a home charger, ensure that your vehicle supports faster charging. Additionally, check if your house or garage has the technical capacity for charger installation. The cost of charging is the same as using an outlet, and it is most cost-effective during off-peak electricity tariffs. Some home chargers come with a power cable, while others have only an outlet, requiring you to use the cable provided with the car, which is now standard for all EVs.
Public AC Chargers
Most public AC chargers support charging up to 22 kW. They are more available and cheaper than DC chargers because the installation and production technology is more affordable. The downside is that they do not provide the fast charging speeds of DC chargers.
Charging at AC stations is optimal for any EV and its battery. Home outlet charging is too slow, keeping the battery in the charging process for too long, which is not ideal. On the other hand, fast DC chargers are also not ideal as the high speed increases heating and puts more strain on the battery system, which is not good for battery lifespan.
Public DC Chargers
DC chargers offer the fastest way to charge an EV battery, often found on highways and at gas stations, where drivers need quick charging. These chargers provide higher charging speeds by bypassing the car’s AC-to-DC converter and directly supplying DC power to the battery.
Charging is not limited by the car’s converter power, allowing for faster charging up to the level supported by the car and its battery. The car always has all necessary protective measures and only allows the amount of electricity the battery can handle. Standard DC stations typically have a power of 50 kW, with the weakest DC chargers being twice as powerful as AC chargers. Power can go up to 150 kW, and Tesla has developed chargers up to 250 kW.
However, using DC chargers is recommended only during travel when quick charging is needed, such as during a coffee break. In everyday situations, like while at work, shopping, or overnight, slower AC charging is recommended as it is healthier for the battery.
Photo: BMW