Level 2 Charging
What Is Level 2 Charging?
Level 2 charging refers to the most common type of electric vehicle (EV) charging that utilizes a 240-volt alternating current (AC) power source, similar to those used for major household appliances. As a critical component of the broader Electric Vehicle Infrastructure, Level 2 charging offers a significantly faster charging speed than Level 1 charging, making it suitable for both residential installations and public charging stations. This charging level is widely adopted for charging Electric Vehicles (EVs) and Plug-in Hybrid Electric Vehicles (PHEVs) in homes, workplaces, and public venues, providing a balance between charging speed and accessibility.
History and Origin
The standardization of EV charging was a crucial step in the widespread adoption of electric vehicles. The Society of Automotive Engineers (SAE) developed the SAE J1772 standard, often referred to as the J-plug or Type 1 connector, which became the universal standard for AC charging in North America. The genesis of this standard can be traced back to efforts by the California Air Resources Board (CARB) in the early 2000s, which advocated for conductive charging over inductive systems previously used by some early electric vehicles. The initial SAE J1772-2001 standard was adopted by CARB in June 2001, allowing for 6.6 kW power delivery. An upgraded design, developed by Yazaki and capable of handling up to 19.2 kW, was proposed by CARB in 2008 and subsequently adopted as SAE J1772-2009 in January 2010. This revised standard gained significant industry support and was integrated into the international IEC 62196-2 standard, establishing the foundation for Level 1 and Level 2 charging widely used today.
Key Takeaways
- Level 2 charging uses a 240-volt AC power supply, offering faster charging speeds than Level 1.
- It is the most common charging method for Home Charging installations and is prevalent at Workplace Charging and Public Charging locations.
- Level 2 chargers typically add 10 to 20 miles of electric travel range per hour of charging.10
- The SAE J1772 connector is the standard plug type for Level 2 charging in North America.
- Installing a Level 2 charger at home usually requires professional electrical work.
Formula and Calculation
The time required to fully charge an EV using a Level 2 charger can be estimated using a simple formula that relates the vehicle's Battery Capacity to the charger's power output.
Where:
- Charging Time (hours): The estimated time, in hours, to charge the vehicle's battery.
- Battery Capacity (kWh): The total energy storage capacity of the EV's battery, measured in Kilowatt-hour (kWh).
- Charger Power (kW): The power output of the Level 2 charger, measured in Kilowatt (kW).
For example, a 60 kWh battery charged with a 7.7 kW Level 2 charger would take approximately ( \frac{60 \text{ kWh}}{7.7 \text{ kW}} \approx 7.8 ) hours to fully charge from empty.
Interpreting Level 2 Charging
Interpreting Level 2 charging involves understanding its practical implications for EV owners. The faster charging speed, compared to Level 1, makes it a more viable solution for daily use, allowing drivers to replenish a significant portion of their battery overnight or during work hours. For instance, a Level 2 charger can add 10 to 60 miles of range per hour, depending on the charger and vehicle's capabilities.9 This increased rate of charge directly addresses concerns about Range Anxiety by providing a more efficient way to maintain a sufficient charge for typical commutes and errands. When considering Level 2 charging, drivers assess the charger's power output in kilowatts (kW) and their vehicle's acceptance rate, as a vehicle can only charge as fast as its lowest limiting factor.
Hypothetical Example
Imagine Sarah owns a battery electric vehicle with a 70 kWh battery. She recently installed a Level 2 Charging Station at her home, which delivers power at 9.6 kW.
Sarah typically drives 40 miles per day. Since her car consumes about 0.25 kWh per mile (meaning 4 miles per kWh), her daily energy consumption is ( 40 \text{ miles} \times 0.25 \text{ kWh/mile} = 10 \text{ kWh} ).
To replenish this 10 kWh using her 9.6 kW Level 2 charger, the charging time would be:
This means Sarah can fully recharge the energy used during her daily commute in just over an hour each night, ensuring her vehicle is ready for the next day. This demonstrates the convenience and practicality of Level 2 charging for routine use.
Practical Applications
Level 2 charging is fundamental to the expansion of electric vehicle adoption across various sectors. Its primary application lies in residential settings, enabling convenient and relatively fast Home Charging for EV owners. Beyond homes, Level 2 chargers are extensively deployed at Workplace Charging facilities, allowing employees to charge their vehicles during the workday. Public spaces such as shopping centers, restaurants, hotels, and parking garages also widely feature Level 2 chargers, often facilitating charging while drivers engage in other activities.8 These public installations play a crucial role in supporting the growing number of EVs on the road and alleviating charging concerns. As of December 2023, approximately 60,000 non-single family residential EV charging locations with about 174,000 charging ports were available in the United States, with over 75% being Level 2 chargers.7 The U.S. Department of Energy's Alternative Fuels Data Center provides comprehensive information and tools for tracking and locating these electric vehicle charging stations.6
Limitations and Criticisms
Despite its widespread utility, Level 2 charging has certain limitations. While significantly faster than Level 1, it is considerably slower than Direct Current (DC) fast charging (also known as Level 3 charging), which can add hundreds of miles of range in minutes rather than hours. This slower speed means Level 2 charging is less ideal for quick top-ups during long road trips where drivers prioritize minimal downtime. Additionally, the installation of a Level 2 charger at home often requires professional electrical work to upgrade existing wiring or install a dedicated 240-volt circuit, which can incur significant upfront costs. While beneficial for Energy Efficiency over fossil fuels, the cumulative electricity demand from widespread EV charging, including Level 2, necessitates ongoing investment in Grid Infrastructure to ensure reliability and capacity. The National Electrical Code (NEC) provides guidelines to ensure safe installation of EV charging equipment, specifying requirements for circuit breakers and wiring to handle the continuous electrical load.5
Level 2 Charging vs. Level 1 Charging
The primary distinction between Level 2 charging and Level 1 charging lies in their power delivery and the electrical outlets they utilize. Level 1 charging uses a standard 120-volt AC household outlet, delivering power slowly, typically adding only 2 to 5 miles of range per hour.4 This method requires no special equipment beyond what comes with the vehicle and is the simplest form of Alternating Current (AC) charging. Conversely, Level 2 charging operates on a 240-volt AC circuit, similar to those used by clothes dryers or electric ovens. This higher voltage allows Level 2 chargers to deliver significantly more power, generally providing 10 to 20 miles of range per hour.3 The confusion often arises because both levels use alternating current, but Level 2 provides a much more practical charging speed for most daily driving needs, while Level 1 is better suited for situations where time is not a constraint or as a supplemental charging option.
FAQs
How long does it take to charge an EV with a Level 2 charger?
The charging time for an electric vehicle using a Level 2 charger varies based on the vehicle's battery size and the charger's power output. Generally, it can take anywhere from 4 to 10 hours to fully charge a battery electric vehicle from empty to 80%, and 1 to 2 hours for a plug-in hybrid electric vehicle.2
Can I install a Level 2 charger at home?
Yes, Level 2 chargers are commonly installed for Home Charging. However, it typically requires a dedicated 240-volt circuit and professional electrical installation to ensure compliance with safety standards and local codes.
Is Level 2 charging safe?
When properly installed by a qualified electrician in accordance with the National Electrical Code (NEC), Level 2 charging is safe. The equipment is designed with safety features to protect against electrical faults.
What is the typical cost of a Level 2 charging station?
The cost of a Level 2 charging station itself can range from a few hundred to over a thousand dollars, depending on features and power output. Installation costs can vary significantly based on your home's existing electrical infrastructure, potentially adding several hundred to a few thousand dollars to the total expense.
Do all electric vehicles use the same Level 2 charging connector?
In North America, most electric vehicles use the SAE J1772 connector for Level 2 charging. Tesla vehicles typically use their proprietary connector but come with an adapter to allow them to use J1772 Level 2 chargers.1