Maximising Your EV Charging Speed: Understanding kW Ratings for EV Chargers

Battery electric vehicles accounted for a record 7.4 per cent of total new vehicle sales in Australia over the first half of 2023.
Source: Car Expert

As more Australians switch to electric vehicles, the demand for efficient and fast charging for EVs increases. Charging speed is a critical consideration when it comes to EVs, and understanding your EV charger kW ratings is the first step toward smart charging strategies. Whether you are looking to reduce downtime on the road or maximise the potential of your home charging setups, understanding kW ratings should be top of mind.

In this blog post, we’ll explain why charging speed matters, how kW ratings measure the speed of your EV charger, what factors influence your Electric vehicle charging speed and how to optimise your home charging set-up for faster charging.

How can I speed up my EV charging?

To begin with, it is important to note that the charging speed of an EV depends on many factors, including the battery capacity, state of charge (SoC), the available charging power, and the charging rate capability of the EV. For instance, a small battery size with a high SoC will charge more quickly than a large battery with a low SoC.

One way to speed up EV charging is to install a more powerful charging station. EV charging speed is measured in kilowatts (kW), which is the charging rate (power) multiplied by the charging time. Generally, the higher the kW rating of the charging station, the faster the charging speed. For example, a 7kW charging station will charge a typical EV in 4-6 hours, while a 22kW charger can charge the same vehicle in less than two hours.

How is charging speed measured?

Charging speed is measured by the charging rate, which is the amount of energy that a charger provides to the battery in an hour. The charging rate is expressed in kilowatts (kW), where 1 kW is the equivalent of 1,000 watts of power. For example, a 7 kW charger will provide seven kilowatts of power to the battery in one hour, while a 22 kW charger will provide 22 kilowatts of power.

What factors influence the charging speed of electric vehicles?

Several factors influence the charging speed of EVs, including the following:

1. Battery Capacity: A larger capacity battery takes longer to charge compared to a smaller one so the larger the battery capacity, the longer it will take to charge. The age of the battery and general EV battery health can also impact charge speeds
2. State of Charge (SoC): A low SoC will generally allow for faster charging, while a higher SoC results in slower charging rates.
3. The kW rating impact: The higher the kW rating of the charger, the faster the charging speed.  An EV only charges as fast as the charger is rated for, so make sure that the charger matches your car
4. Cable thickness: Thicker cables can accommodate higher charging rates and result in faster charging.
5. Temperature: Extremely cold or hot temperatures will interfere with battery charging time. Charging in hotter temperatures reduces the charging speed while charging in cooler temperatures results in faster charging.

How can you optimize your home charging set-up for faster charging?

In addition to selecting the right kW rating charger, there are several strategies you can use to optimise your home charging set-up for faster charging efficiency.

Here are a few practical tips to optimize your home charging setup:

1. Upgrade your charger: Upgrading to a more powerful charger is the quickest way to achieve faster charging speeds. If you have a 3.7 kW charger, consider upgrading to a 7 kW or 22 kW charging station.

2. Charge in off-peak hours: In Australia, off-peak electricity rates are generally lower. Charging your EV during off-peak hours will save you money and allow for faster charging rates.

3. Invest in a thicker cable: Upgrading your charging cable to a thicker one can accommodate higher charging rates and provide faster charging. Also at Supreme Solar Power, we encourage you to ensure that your electrical systems can handle the load that comes with a higher kW rated charger.

4. Keep your battery cool: Parking your EV in a cool, shaded area will allow for faster charging as EV batteries charge more efficiently in cooler temperatures.

5. Manage your charging session: You can optimize the charging speed by adjusting the charging rate to maximize the available power. Turn off unnecessary appliances in the house that draw power, and avoid charging multiple cars at once to maximize the available charging power.

Conclusion

Understanding the technical details of kW ratings for EV chargers can help you maximize your EV charging speed. The charging speed of an EV depends on several factors, including battery size, SoC, charger power, cable thickness, and temperature. Optimizing your home charging setup with a higher kW charging station, thicker cables, charging during off-peak hours, and managing your charging session can significantly improve the EV charging speed. Hence, it is essential to do your research before purchasing a charging station and invest in an EV charging setup that suits your needs.