The efficiency of electric vehicle (EV) charging is a critical factor for both cost and environmental impact. Recent tests conducted by the ADAC a prominent German automotive club, have shed light on the varying levels of energy loss that occur during different charging scenarios.
Understanding these losses can help EV owners make informed decisions about their charging habits and setups. The study examined five different electric vehicles, evaluating their performance across various charging methods, including standard household outlets, wallboxes, and solar-powered charging.
Charging at a standard household outlet
The study found that charging an EV using a standard household outlet results in the highest energy losses. The Mercedes CLA 350 EQ showed the most significant loss, with nearly a quarter of the energy not reaching the battery. Other models in the test had losses ranging from 13% to 15%.
The primary reason for these losses is the conversion of alternating current (AC) to direct current (DC) within the vehicle’s onboard charger. Additionally, auxiliary systems such as the infotainment system and climate control remain active during charging, consuming energy that does not contribute to charging the battery.
Charging with a wallbox
Wallboxes, which are dedicated home charging stations, offer a more efficient charging solution. The study found that losses were significantly lower when using a wallbox, ranging from 5.1% to 7%. The Renault 5 performed the best in this category, with the lowest energy losses.
The higher power output of wallboxes means that the charging process is completed more quickly, reducing the time during which auxiliary systems consume energy. This efficiency makes wallboxes a cost-effective and practical solution for home charging.
Charging with solar energy
Charging an EV using excess energy from a solar photovoltaic system is an eco-friendly option, but it comes with its own set of efficiency considerations. The study found that losses ranged from 8% to 13% when charging at a reduced power of 4.2 kW.
While the efficiency is not as high as with a wallbox, the environmental benefits of using solar energy make it a viable option for many EV owners. The ADAC recommends this method for those looking to maximize the use of their own renewable energy sources.
DC fast charging
DC fast charging stations bypass the onboard charger, converting AC to DC within the charging station itself. This results in lower conversion losses, averaging around 3%. However, the
If the battery needs to be heated or cooled, the energy required for this process is drawn from the charger, increasing the total losses to between 5% and 15%. Preconditioning the battery while driving to the charging station can save time but does not necessarily result in energy savings.
The study highlights the importance of considering both efficiency and cost when choosing a charging method. While DC fast charging is more efficient in terms of energy conversion, the higher cost per kilowatt-hour at public stations often offsets these benefits. For most EV owners, home charging with a wallbox remains the most cost-effective and efficient option.
