Factors Affecting Charging Speed
Sep 21, 2023
Electric Vehicle Battery Capacity
It's simple: the larger the battery, the longer it takes to charge. Electric vehicle battery capacity is measured in kilowatt-hours (kWh), similar to liters or gallons, but in terms of electricity, each kilowatt-hour represents the energy consumed by a 1,000W device running for one hour. Nowadays, most electric passenger car batteries can hold between 25 to 100 kWh of electricity when fully charged.
Maximum EV Charging Power the Vehicle Can Handle
The maximum charging input power that an electric vehicle battery can accept varies from vehicle to vehicle and even by model. The EV Charging output power, measured in kilowatts, for both AC and DC charging plays a significant role in charging time. For example, two electric cars with similar battery capacities charging side by side at a high-power DC charging station may have different charging speeds. One may only accept 50 kW of DC power, while the other can handle up to 250 kW, resulting in significantly faster charging for the latter.
Maximum Output Power of Charging Stations
The output power of EV Charging stations, whether AC or DC, and the different output power levels, have a significant impact on the time required to charge electric vehicles. Higher power output at charging stations leads to faster charging speeds.
Remaining Battery Capacity Before Charging
The remaining capacity of the battery when you are ready to charge also affects the charging time. For instance, if the battery capacity is above 80% before charging, reaching 100% might take only ten minutes. If the battery is at only 20%, it might take more than 30 minutes to fully charge. Just like refueling a conventional car, the time required depends on whether your fuel tank is half full or nearly empty.
DC Charging Curve
When using AC charging, the power flow to an electric vehicle is relatively constant (meaning it charges at the same rate from 0% to 100%). However, with DC charging, the electric vehicle's battery initially receives a faster power flow, then gradually tapers off as it approaches full charge. This is done to prevent damage to the battery due to a sudden surge in electricity. Therefore, when using DC or Level 3 chargers, the initial phase of charging (up to 80%) is faster (possibly taking a similar amount of time as the first 80% as a whole) than the final 20%.
Another factor that determines charging time is the weather. Charging an electric vehicle will take longer in extremely hot or cold weather because batteries operate less efficiently in these conditions. In warm weather (around 20-25°C), batteries tend to perform better, resulting in faster charging times.