In the era of electric mobility, it is crucial to understand some fundamental technical concepts to make the most of the technology and ensure efficient charging of electric vehicles. Two common but often confusing terms are the kilowatt (kW) and the kilowatt-hour (kWh). In this article, we will explore the difference between kW and kWh and how they relate to electric car chargers.

What is a kilowatt (kW)?

A kilowatt (kW) is a unit of power. It represents the amount of energy being used at a given time. It is similar to the speed at which a vehicle is travelling at a specific time. In the context of electric car chargers, the kW is used to measure the power that a charger can deliver to the electric vehicle during charging.

In simpler terms, the kilowatt refers to the rate at which energy is being consumed or supplied at any given instant. For example, a 7 kW electric car charger delivers a constant 7,000 watts of power while the vehicle is charging.

What is a kilowatt-hour (kWh)?

A kilowatt-hour (kWh) is a unit of energy. It represents the total amount of energy consumed or supplied over a period of time. It is similar to the distance a vehicle travels during a complete journey. In the context of electric car chargers, kWh is used to measure the total energy that has been supplied to an electric vehicle during charging.

That is, the kilowatt-hour refers to the total amount of energy that has passed through the charger during a specific period. For example, if an electric car has been charged for one hour at a constant power of 7 kW, the total energy supplied would be 7 kWh.

Relationship between kW and kWh in electric car charging:

The relationship between kW and kWh is essential to understanding the charging capacity of an electric car charger. The power (kW) determines the charging speed, while the energy (kWh) indicates the total amount of charge delivered.

For example, if an electric car charger has a charging power of 50 kW and is used for one hour, it will have delivered 50 kWh of energy to the electric vehicle. If it is used for 30 minutes, it will have delivered 25 kWh.

It is important to note that not all electric cars can accept the same charging power. Some vehicles are limited to a maximum charge of, for example, 11 kW, while others can accept a charge of up to 150 kW or more. Knowing your vehicle’s charging capacity is essential to get the most out of the charging speed your charger can provide.

In conclusion, understanding the difference between kW and kWh is essential to effectively use electric car chargers. Kilowatt (kW) refers to the power supplied at a given time, while kilowatt-hour (kWh) indicates the total amount of energy supplied over a period of time. Knowing how these terms relate to electric vehicle charging will allow you to optimise your charging experience and maximise the efficiency of your electric vehicle.

Remember, higher kW does not always mean faster charging, as the vehicle’s acceptance capacity is also a determining factor!