A Complete Guide to Level 2 Charging: Speed, KW, and Time
As the shift toward sustainable transportation continues to accelerate, electric vehicles (EVs) have become the preferred choice for a growing number of vehicle owners. Recent industry reports indicate that by 2030, several flat-fifths of the cars on U.S. and European Union roads will be electric, demonstrating the growing acceptance of EVs in these markets. However, as the popularity of electric vehicles grows, a key question is surfacing: how to charge them quickly and efficiently?
For many car owners, the Level 2 EV Charger may be the best answer to this problem. Not only does it provide a faster charging experience at home or at a public charging station, but it also significantly reduces charging time for daily commutes and long-distance trips.
In this article, we will take a closer look at the charging speed, power output, and charging time of Level 2 chargers, and analyze the key factors affecting EV charging time to help you better choose the charging solution that’s right for you.
Level 2 charging time
Level 2 EV charging is much faster than Level 1 charging, which uses 208/240V AC in the U.S. and can be as powerful as 19.2kW, while in Europe Level 2 charging typically uses 230V (single phase) or 400V (three phase) AC and can be as powerful as 22kW. These higher voltages and powers make Level 2 charging more efficient than Level 1 charging.
- Charging Time: Level 2 charging can provide an electric vehicle with a range of approximately 10 to 73 miles (16 to 117 kilometers) per hour, depending on the power output of the charger and vehicle compatibility. At this level of charging, the average EV battery takes 4 to 24 hours to fully charge.
Level 2 chargers are suitable for use in homes, workplaces, hotels, retail parks and supermarkets for long periods of parking and charging.
Both Level 1 and Level 2 charging involves delivering alternating current (AC) to the electric vehicle, which is then converted to direct current (DC) by the vehicle’s on-board charger and delivered to the battery.
Factors affecting the charging time of electric vehicles
Charging times for electric vehicles can vary significantly depending on a number of factors. Understanding these factors can help owners better plan their charging time and thus use their EVs more efficiently. Below is a detailed analysis of these key factors:
1. Battery architecture (voltage system)
Modern electric vehicles typically utilize 400-volt or 800-volt battery systems. Higher voltage systems (such as the Tesla Cybertruck or Porsche Taycan) can support higher charging rates. For example, an EV with a 400-volt system may have a maximum charge power of about 150kW, while a vehicle with an 800-volt system may have a charge rate of 360kW or more. As a result, an 800-volt system can complete charging in a much shorter period of time, significantly reducing the total charging time.
2. Battery capacity
The battery capacity of an electric vehicle is usually measured in kilowatt-hours (kWh) and is the central determinant of charging time. The larger the battery capacity, the more energy is stored and the longer the charging time. For example, all other things being equal, an EV with a 30kWh battery will charge faster than a vehicle with a 100kWh battery.
3. Maximum charge acceptance rate of the vehicle
Each electric vehicle has a maximum charging power it can accept, which may be lower than the output power of the charging station. For example, if the vehicle has a maximum charge rate of 100kW, it will not charge faster than 100kW even when connected to a 180kW charger.This charge rate is determined by the vehicle’s on-board charging hardware and battery management system. Most electric vehicles have two charge acceptance rates: one for AC charging and one for DC fast charging.
4. State of charge (SOC) of the battery
The initial state of charge (i.e., percentage of charge) of a battery also affects charging time. Generally, batteries charge faster when they are at a lower charge level and slower as they approach full capacity. As the battery approaches full capacity, the electric vehicle’s charging system reduces power output to protect battery health and safety.
- Charging speeds are relatively stable when using AC charging stations;
- DC fast charging stations, on the other hand, reach their fastest charging speeds when the battery is between 20% and 60% of capacity, while charging slows down significantly to protect the battery as it approaches 80% to 100% capacity.
5. Power output of the charging station
The maximum power output of the charging station is one of the key factors influencing the charging time. Even if the vehicle is able to accept high power charging, the charging time depends on whether the charging station is able to provide the appropriate power. Differences in the power output of a charging station can significantly affect the charging speed. Charging stations are usually categorized into three levels, each providing a different power output, which affects the charging speed.
6. Environmental factors
Extreme temperatures can affect battery performance and charging speed. In cold weather, the battery may need to be warmed up using the charger’s energy, which can reduce charging speed. Similarly, in hot environments, the cooling system may need to run to keep the battery at an optimal temperature, which can affect overall charging efficiency.
Charging Speed and Power Output
The power output of a Level 2 charger varies depending on the charger and the vehicle’s compatibility. On average, Level 2 chargers provide anywhere between 3.7 kW to 22 kW. Here’s a breakdown:
- Lower Power (3.7 kW – 7.6 kW): These are often used for residential or small-scale commercial installations. Charging speeds typically range from 10 to 25 miles of range per hour.
- Higher Power (11 kW – 22 kW): These chargers are often found in commercial locations or higher-end residential installations. Charging speeds can range from 25 to 60 miles of range per hour or more, depending on the vehicle’s charge acceptance rate.
Estimating charging times for electric vehicles
Charging time (hours) = Battery capacity (kWh) × Remaining battery capacity / Charging power (kW) or Vehicle Charging Acceptance Rate (kW), whichever is lower.
Explanation of the terms:
- Battery capacity (kWh): This is the total energy storage capacity of the EV’s battery, typically measured in kilowatt-hours (kWh). For example, a battery might have a capacity of 60 kWh.
- Remaining capacity (kWh): This is the amount of charge left in the battery, which is calculated by subtracting the current charge from the total battery capacity.
Remaining capacity (kWh) = Battery capacity (kWh) – Current charge (kWh). If a 60 kWh battery has 20 kWh remaining, the remaining capacity is 40 kWh. - Charging power (kW): This refers to the rate at which the charging station delivers power to the vehicle’s battery, measured in kilowatts (kW). A Level 2 charger might provide 7.4 kW, 11 kW, or 22 kW depending on the setup.
- Charge acceptance rate (kW): This is the maximum rate at which the EV’s battery can accept power. It’s often lower than the charger’s output power. For example, if the car can accept a maximum of 7.4 kW, even if the charger can provide more, the rate will be capped at 7.4 kW.
Step-by-Step Calculation:
- Determine battery capacity: Your EV’s battery’s total energy storage capacity is listed in kWh. For instance, if your EV’s battery capacity is 80 kWh, you’ll use this figure.
- Assess Current Battery State of Charge: Check how much charge your battery has. This information is accessible on your in-vehicle display. lf your battery is 50% charged and the total capacity is 80 kWh, the current charge is 40 kWh. Thus, you need to top up 40 kWh to reach ful charge.
- Charger Power Output: This is the maximum rate at which the charging station can deliver power to your EV, which is measured in kW.
- Vehicle Charge Acceptance Rate: This is the maximum power in kW that the vehicle’s battery can input from an AC or a DC charger. The DC charge acceptance rate will be much higher than the AC acceptance rate.
- Calculate charging time: Subtract the current battery state of charge from the total capacity to find out how much energy is needed. Then, divide this number by the power output of your charger or the vehicle’s charge acceptance rate, whichever is lowest.
Example of electric vehicle charging time calculation
Given conditions
- Battery capacity: 80 kWh
- Current charge: 50% (i.e. 40 kWh)
- Charge acceptance rate: 11 kW
- Charger power used: 7.6 kW
Calculation:
Required power = Battery capacity – Current charge level
Required power = 80 kWh – 40 kWh = 40 kWh
Charging time = Required power / Charging power
Charging time = 40 kWh / 7.6 kW ≈ 5.26 hours
Explanation:
In this example, although the charging acceptance rate of the EV is 11 kW, the charging time is calculated based on the power of the charger, not the charging acceptance rate, since the charger we are using has a maximum output of 7.6 kW.
Therefore, the final charging time is 5.26 hours, which is determined by the power of the charger.
Consider the reduction effect
A gradually decreasing charge rate is especially important for electric vehicles, especially when using DC fast charging. As the battery nears full capacity, the charge rate slows down significantly to protect the life and health of the battery. This phenomenon means that during the last 20% of the charge, the charge rate may be much slower than the first 80% of the charge.
Each EV has a unique charging profile and the length of charge time varies as a result. Even if two EVs have the same DC charging acceptance rate, their actual charging speeds and charging times after they are plugged in to charge at a charging station may differ depending on their respective charging curves. This makes it more difficult to accurately estimate the time required to charge an EV using a DC fast charging station.
Typically, the charging rate of an electric vehicle varies as it reaches between 10% and 80% charge. Specifically, a vehicle’s charge rate may fluctuate between 40% and 90% of its maximum charge acceptance rate.
| Model | Maximum Charge Acceptance Rate | Average Charging Power(10%-80%) | Percentage of |
| Genesis GV60 Premium | 233 kW | 200 kW | 86% |
| Volkswagen lD Buzz GTX | 185 kW | 130 kW | 70% |
| Hyundai lONlQ 6 | 175 kW | 140 kW | 80% |
| Ford Mustang Mach-E | 150 kW | 95 kW | 63% |
| Mini Aceman SE | 95 kW | 76 kW | 80% |
| Porsche Taycan Plus | 320 kW | 230 kW | 72% |
| Lotus Emeya S | 350 kW | 240 kW | 69% |
| MG 4 | 142 kW | 116 kW | 82% |
| BYD ATTO 3 | 89 kW | 73 kW | 82% |
| Tesla Model 3 | 170 kW | 100 kW | 59% |
As you can see from the table above, each EV has a different charging time depending on its unique charging profile; this makes the previous formula not applicable to DC fast charging. You will need to check the specifications of your particular EV to see the charging times when using a DC fast charger.
Electric Car Charging Time
Below is a comparison of battery capacity, charge acceptance rate, and estimated charging time for some of the most popular electric vehicles. These data can help you understand how different electric vehicles perform when using DC fast charging:
| Battery Size(usable) | AC ChargeAcceptance Rate | Estimated AC ChargeTime 0%-100% | DC Charge AcceptanceRate(maximum) | Average DC ChargeRate 10%-80% | Estimated DC ChargeTime 10%-80% | |
| Audi Q4 (e-tron 45Quattro) | 77 kWh | 11 kW | 7 hours | 175 kW | 120 kW | 27 minute |
| BMW i4(eDrive35) | 67 kWh | 11 kW | 6 hours 6 mins | 180 kW | 95 kw | 30 minute |
| Tesla Model Y(RWD) | 68 kWh | 11 kW | 6 hours 12 mins | 170 kW | 100 kW | 29 minutes |
| Tesla Model 3(RWD) | 68 kWh | 11 kW | 6 hours 12 mins | 170 kW | 100 kW | 29 minutes |
| Dacia Spring (45) | 25 kWh | 6.6 kW | 3 hours 48 mins | 34 kW | 29 kW | 37 minutes |
| Volkswagen lD 3(Pro) | 58 kWh | 11 kW | 5 hours 18 mins | 120 kw | 80 kW | 31 minutes |
| Fiat 500 | 21.3 kWh | 11 kW | 1 hour 54 mins | 50 kW | 40 kW | 23 minutes |
| Skoda Enyaq(60) | 58 kWh | 11 kW | 5 hours 18 mins | 124 kW | 82 kW | 30 minutes |
| Volkswagen lD 4(GTX) | 77 kWh | 11 kW | 7 hours | 175 kW | 120 kW | 27 minutes |
| MG 4 | 51 kWh | 6.6 kW | 7 hours 42 mins | 87 kW | 68 kW | 32 minutes |
The provided charging times are approximate and serve merely as a general guide for comparison purposes. Real-world charging durations are influenced by a variety of factors, such as the vehicle’s charging capacity, usable battery capacity, energy losses, current state of charge, charger output, and environmental conditions.
Grasping the intricacies of estimating electric vehicle charging times and the elements that impact them is crucial for both current and potential EV owners. It enables them to manage their charging expectations effectively and make well-informed choices regarding electric vehicles and charging infrastructure.
Conclusion
Level 2 charging provides an ideal balance of speed and convenience for most EV owners. It’s widely available, cost-effective, and provides fast-enough charging speeds for daily use. Whether you’re installing a charger at home or relying on public charging stations, Level 2 chargers offer a reliable way to keep your EV ready for the road. However, always keep in mind the vehicle’s charge acceptance rate and the available charger power to ensure you’re optimizing your charging times.