Introduction:
The world of electric vehicles & their charging needs is new for people. We are well-versed about how petrol/diesel cars work, how they can be refuelled at petrol pumps and so on. But the same is a bit complicated for electric cars. In the EV world, public charging stations take place of petrol pumps. Most public EV charging stations are made to offer fast charging. Some premium electric cars have a ‘high charging capacity’. All this might sound a bit confusing but the heart of the matter is that it is important to be aware of your ‘charging capacity needs’ before selecting an EV charging station.
Battery Capacity & Its Power Intake:
EV battery capacity is the total amount of energy your EV’s battery can store, which is measured in kWh. If your EV has a 40 kWh battery, it means it can store 40 kWh of energy. However, this is different from the battery’s power intake capacity, which is the maximum power level at which your EV can accept a charge. This is measured in kW. If your EV can charge at a maximum rate of 50 kW, it means it can take in 50 kW of power per hour.
When charging your EV at public EV charging stations, you might notice the charging point capacity listed as 30 kW, 60 kW or 120 kW on the EV charging app. Many EV users often confuse this with the battery capacity of their electric car, leading to underutilization of the charging stations. In this blog, EVJoints will guide you on how to choose the ideal EV charging station for your needs.
What is Charging Capacity?
Different electric cars have different capacities for charging. And different EV charging stations also have different capacities. The maximum rate of your charging session is determined by whichever is lower, the charging capacity of your car or the EV charger. For instance, an electric car with a charging capacity of 50 kW would not charge any faster at a 120 kW station. Also, it is worth noting that cars with higher charging capacity can charge at lower capacity stations. They will just be limited to what the station can provide.
When an electric car claims a maximum charging rate of 50 kW, that doesn’t mean it will consistently charge at that rate.
Charging capacities/capabilities vary among different electric cars and regulate the speed you can charge at. The charging process will be limited to the maximum capacity supported by your EV. If the car has a maximum capacity of 50 kW, the EV charging station will automatically ensure that the charging does not exceed 50 kW, even if the charging station is able to do more than that.
To learn about the charging capability of your electric car in kilowatts (kW), check with the employees at the car dealership or dig deep in the owner’s manual for specifications of your electric car.
If you have an EV with 7.2 kW maximum charging capacity, you can still charge it at a charging station providing a higher capacity, say 22 kW, because the EV’s hardware is pre-programmed to accept a fixed power. You can only charge the EV at the maximum charge rate the battery can accept. If your EV’s max charge rate is 7 kW, you won’t charge any faster by using a 22 kW EV charger.
The time it takes to charge the EV is also limited by the maximum charging rate of the EV charger you are using. For instance, if your vehicle can charge at 11 kW, but you are using a 7.2 kW charger, it will only charge at 7.2 kW, which is the maximum capacity of the charger.
Examples:
Firstly, we take India’s most popular electric car, the Tata Nexon EV, as our subject. The Nexon EV long range variant comes with a 40.5 kWh battery.
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We have gathered from multiple customer reviews that the Nexon EV’s maximum charging speed/capacity is 30 kW. So even if you go to a 60 kW or a 120 kW DC charger, the peak will always remain at 30 kW. If you have two options in front of you: a 60 kW charger & a 120 kW charger, go for the 60 kW option. If you choose the 120 kW charger, you’ll still be charging at 30 kW and will have to pay extra for no good reason. Below we’ll have a look at details of Zeon Charging’s EV charging station in Erode (Tamil Nadu):
The station offers two options for DC fast-charging: a 60 kW station priced at ₹22.90 per kW and a 120 kW station priced at ₹24.90 per kW. If you’re using a Nexon EV for a quick top-up here, it’s better to choose the 60 kW option over the 120 kW one, as explained earlier. This choice can also save you money per kWh.
Do You Know?
A few customers prefer charging their Nexon EV at 60 kW chargers because it charges at 30.5 kW speed there as compared to a 30 kW charger where it charges at 29 kW.
Secondly, we’ll take into consideration the MG ZS EV:
MG ZS EV features a 50.3 kWh battery. As per multiple reviews, it has been ascertained that the ZS EV supports maximum DC charging between 75-80 kW. EV chargers with higher output than this will be confined to this limit. In the image below, we can see the car’s charging times at different charging stations:
Since the ZS EV’s maximum charging speed is limited to 75-80 kW, charging at a 150 kW or 350 kW station won’t reduce the charging time below 33 minutes, which is the time it takes at a 150 kW station.
Conclusion:
The rate at which electric vehicles charge is usually decided by the vehicle’s Battery Management System (BMS). The main function of the BMS is to make sure that any action out of the battery’s safety limit is avoided. When an EV connects to a charger, a deliberation takes place between the charger & the BMS, and it’s dominated by the BMS. It tells the charger what rates it can accept, and the charger provides only what the battery can contain.
