Losses during charging of electric vehicles are well-documented and vary depending on the type of charger being used. When electricity is transferred from one point to another, there are inevitable transmission losses, with higher losses occurring when the electricity is moved over longer distances. The lost electricity typically converts into heat, dissipating energy in the process. Higher transmission voltages generally result in lower losses as electricity is moved through the grid, which is more efficient when the voltage is higher. However, stepping down electricity from high-voltage lines to lower-voltage power lines creates additional losses, as does the conversion from alternating current (AC) to direct current (DC) needed for EV charging.
To observe EV charging losses firsthand, one could completely drain an EV’s battery, then charge it to full capacity and measure the amount of electricity used in the process. This test would reveal that it typically takes around 10% more electricity than the advertised battery capacity to fully charge an EV, with the extra energy consumed attributed to charging losses. A study conducted by ADAC in Germany with a BMW iX and a 22 kW AC wall charger found that charging the vehicle’s 105.2 kWh battery pack required around 125.2 kWh, representing approximately a 20% loss. Similar findings were reported with Tesla’s Model Y Performance, which showed a 14% loss when charging from a 240-volt Level 2 charger. Charging losses using AC chargers are influenced by factors such as the EV’s onboard converter, the charger, and battery characteristics.
Charging your EV from a Level 3 DC fast charger offers reduced losses compared to AC charging, as there is no need for current conversion from AC. Data on exact loss percentages with DC fast chargers are less readily available, but estimates suggest losses may be around 10%. An example with a Tesla Model 3 charging at a DC fast charger showed approximately 10% losses when adding energy to the vehicle’s battery pack. This indicates that DC fast charging is more efficient compared to AC charging methods. However, frequent fast charging can potentially accelerate battery degradation, so it may not be the best long-term charging solution for preserving battery capacity.
Paying attention to the type of charger used can minimize charging losses, with Level 3 DC charging offering the most efficiency and lowest losses. Level 1 charging should be avoided as it appears to be the least efficient charging method, resulting in higher losses. While Level 3 DC charging offers lower losses, it’s important to consider the potential impact on battery health with frequent fast charging. Ultimately, EV users are paying for electricity losses between the charger and the vehicle’s battery pack, with most of the lost energy dissipating as heat. By selecting the most efficient charging option and balancing fast charging with battery preservation, EV owners can optimize the charging process and minimize losses over time.
