## kW and kWh, what do they mean?

When the topic about EV cars is brought up, these two terms, kW and kWh will always be brought up. But what do they mean exactly?

Kilowatts (kW) and kilowatt-hours (kWh) are terms used in anything related to electricity and energy. Understanding the difference between these two terms is essential in better understanding more about EV cars.

## What is a Kilowatt (kW)

A kilowatt (kW) is a unit of **power **which is the rate at which energy is **used or produced**. One kW equals to one thousand watts. It measures how much energy is required to operate or power anything electrical such as EV cars.

__For example:__

An electrical motor with a power rating of 50kW means that if can use 50kW of power at full load.

## What is a Kilowatt-hour (kWh)

A kilowatt-hour (kWh) is a unit of **energy** which is the amount of energy **used or produced over a period of time**. One kWh equals to the amount of energy used by a one kW appliance operating for one hour. It can also be the amount of energy produced by a one kW generator operating for one hour.

__For example:__

If an EV uses 10kWh to travel 100 kilometers, it means that the EV used 10kWh of energy to cover 100 kilometers.

## Differences

kW measures power which can be seen as instantaneous usage where as kWh measures energy which is the total usage over time.

kW can be seen as the speed of a car, its current speed. kWh can be seen as the distance covered by the car, the total distance driven over time.

## What they mean for EV cars

When charging your EV, you would typically see your EV chargers, AC or DC showing the power rating such as 11kW or 50kW. This tells you how fast the charger can supply energy to your EV.

__For example (EV Charging):__

When using a DC with 50kW rating for 4 hours, the total amount of energy used is 200kWh.

50 kW x 4 hours = 200 kWh

Note that although the time was 4 hours, the unit still used is kWh.

__Another example (Battery Capacity):__

Typically the capacity of an EV battery is stated in kWh which indicates how much energy the battery can store. If an EV battery has a capacity of 100kWh, this means that the battery can store 100kWh of energy when fully charged. Take note again that there is no mention of time here.

__Last example (Energy Consumption):__

EVs are rated based on how efficiently they use energy which is generally shown as kWh per 100 kilometers. If an EV uses 20kWh to travel 100 kilometers, its energy efficiency would be 20kWh/100 kilometers.

## How it affects you

**Using the Right Charger:**

If you urgently need to charge your battery as much as possible, the most obvious decision would be to choose a charger which has a high kW rating. Typically DC chargers have higher kW ratings than AC chargers.

__For example:__

A 120kW charger will charge your EV six times as fast as compared to a 20kW charger.

It is best to note that you have to consider your EV’s acceptable charging limit as well.

Looking at the Hyundai iONIQ 5, it has an AC charging limit of 11kW and a DC charging limit of 350kW. This means that when using any AC charger with a rating above 11kW, it will only charge at 11kW maximum. Similarly with DC, when using any DC charger with a rating above 350kW, it will only charger at 350kW maximum.

Comparing this to the Nissan LEAF which has an AC charging limit of 7kW and a DC charging limit of 50kw. This means that when using any AC charger with a rating above 7kW, it will only charge at 7kW maximum. When using any DC charger with a rating above 50kW, it will only charge at 50kW maximum.

**Understanding the Range:**

Knowing your EV’s energy efficiency (kWh/100 kilometers) is important before planning any drives out.

__For example:__

If you plan to drive 200 kilometers with an EV that has a 100kWh battery capacity and an energy efficiency of 25kWh/100 kilometers, you would be using approximately 50% of your battery or 50kWh which leaves you with another 50% or 50kWh if you had a full battery.

This information is especially useful when planning when to charge your EV and for how long.

**Calculating costs:**

Based on all the information we have given so far, you can use it to help you calculate how much it would cost you to charge your car or how much it cost to travel a certain distance. You can use our in-built calculator ** here** to help you calculate how much it cost to charge your EV!

__For example:__

Most EV charging stations show the cost at $/kWh. Shell recharge costs $0.65/kWh (not inclusive of GST). If your car efficiency is 25kWh/100 kilometers, this means that the cost to travel 100 kilometers is:

25kWh x $0.65/kWh = $16.25

Another factor which can impact the cost of charging is parking fees. Typically parking fees are charged per half an hour so if you have to stay longer to charge due to a low kW rating charging station, you might be paying a lot more in terms of parking fees.

We are in the works of developing a calculator which can help to approximate the cost of charging based on the parking fees and the duration spent there so keep a look out!

## Conclusion

Knowing the difference between kW and kWh is important for any EV owner. kW is the rate at which power is being used while kWh is the total amount used over a period of time. This will help you make better decisions about charging, efficiency, choosing the type of EV and other costs related to EVs.