Most electric cars today support AC charge speeds up to 7.4kW. A 7.4kW charger adds around 30-miles of range to a lithium-ion battery per hour. The length of time the battery takes to charge to 100% depends on the battery capacity.
For example, with a 7.4kW charger, a 60kWh battery will take 8 hours 10 minutes to charge from 0-100% (60kWh ÷ 7.4kW = 8.10).
A slower charger takes longer. For instance, a 3-pin plug charges at 2.3kW and will take 26-hours to charge a 60kW battery from 0-100%.
Whether an electric car supports 7.4kW charge speeds depends on the type of onboard charger it has, which converts AC power to DC power.
Car batteries only accept DC power, but home chargers output AC power, so cars have an onboard charger to convert the current. The limitation lies in the AC-DC conversion. Some onboard chargers are faster than others. Today, the fastest onboard chargers are 11kW, so they accept single and three-phase AC chargers up to 11kW.
DC public charging stations are significantly faster than home chargers. They can charge most cars from 0-80% in 35 minutes or less. After 80%, the charge speed is slowed down by DC chargers to stop the battery from overheating.
The fastest viable charging technology today is 800-volt electrical architecture used by Porsche and the Hyundai IONIQ 5 range. This architecture enables charge speeds of 0-80% in less than 20 minutes. However, you need to use a 350kW DC charger to unlock these speeds.
