The charging time of a vehicle depends on the car battery capacity and the charging power. Here’s the basic formula:
Charging Time (h) = Battery Capacity (kWh) / Charging Power (kW)
Battery capacity refers to the total energy the vehicle’s battery can store. It’s also important to consider that the battery will be at different charge levels each time you charge. It’s recommended to charge the battery between 20% and 80%.
Charging power is determined by the most restrictive factor between the charger’s power capacity, the cable’s charging capacity, and the EV’s charging capacity. For example, if you have a 7.4 kW charger, a 7.4 kW car, and a 4 kW cable, the charging power will be 4 kW.
Additionally, note that even if a charger has a maximum power of 22 kW, it doesn’t always charge at this maximum power. With dynamic load balancing, the charging power adjusts according to the building’s consumption. For example, if you have a 30 kW power contract and the building consumes 20 kW, the charger will operate at 10 kW.
Example 1: An EV with a 50 kWh battery at 0%, using a 7.4 kW charger (single-phase AC).
Charging Time (h) = 50 (kWh) / 7.4 (kW) = 6.76 h
Example 2: An EV with a 90 kWh battery at 50%, using a 22 kW charger (three-phase AC).
Charging Time (h) = (90 (kWh) * 0.5) / 22 (kW) = 2.04 h