What is EVSE?

For prospective electric vehicle owners, becoming familiar with the terminologies and acronyms can be a daunting task. BHEV, PHEV, NEMA, CCS, NACS - these are among the most common ones, and the list goes on. But one acronym you might not have heard of is EVSE - Electric Vehicle Supply Equipment. It is also referred to as an EV charging station, which is the more commonly used term.

Although the two essentially refer to the same thing - a piece of equipment used to supply electric energy to electric vehicles - EVSE is the more accurate and technical term as it encompasses the components of an EVSE.

So, what exactly is an EVSE?

What is Electric Vehicle Supply Equipment?

Electric Vehicle Supply Equipment (EVSE) refers to the equipment or hardware used to supply electricity to electric vehicles for the purpose of recharging their batteries. The EVSE system encompasses the connectors, cables, electrical conductors, related equipment, software (including communications protocols), and any other infrastructure necessary to deliver electric power to an EV in a safe and efficient manner. EVSE acts as an intermediary between the power supply (typically the electrical grid) and the electric car, ensuring the safe and controlled transfer of electricity.

For the most part, electric vehicle charging involves connecting a cable to a charging station much like how you would charge your smartphone. However, EV charging stations don't always recharge electric vehicles. Instead, an onboard charger does the job.

The anatomy of EVSE

The EVSE is a complex system comprised of various components designed to facilitate the charging of electric vehicles. To better understand how EVSE systems work, let's break down its anatomy

Housing or Enclosures

EVSE units come in various forms and sizes, each tailored to specific applications:

• Box-on-a-cable: These are typically used for home charging, with the charger housed in a box that is attached to the charging cable.

• Wall- and Pedestal-mounted devices: These are versatile and can be used in a variety of settings, such as home, multi-family residential, workplace, fleet, hotel, retail, and public charging. Wall-mounted units are affixed to a building, while pedestal-mounted units stand independently.

• Towers: These tall structures are commonly seen at public and fleet depot charging locations, where multiple charging stations are available for use.

Electronics

The electronic components of an EV charger include:

• Main Relay: This component switches power to the vehicle on or off as needed.

• Control Module: The control module manages the relay and the entire charging session. It oversees the charging process, including start and stop commands.

• Power Supply: The power supply provides the necessary electrical energy to both the control module and the relay.

• Electrical Circuits: Each charging socket (port) or fixed cable attachment has its dedicated electrical circuit to manage the flow of power to the vehicle.

• User Interface: Some EVSE units feature an interface, such as an LCD screen, to facilitate user interaction and provide essential information about the charging session.

Firmware

Firmware is a type of software that is embedded into the hardware components of the EVSE. It is stored in read-only memory and plays a critical role in enabling these components to function correctly. The EVSE controller firmware offers various functions, including:

• Starting and stopping charging sessions.

• Ensuring electrical safety.

• Providing cybersecurity protection.

• Communicating with the electric vehicle to assess battery condition, state of charge, and power requirements.

Firmware can be updated to introduce new features or enhance compatibility with different EV brands and models.

Network Connectivity (Optional)

Smart EV chargers are equipped with network connectivity options, including WiFi or cellular connections. This connectivity enables communication between the charger and other systems, such as mobile apps, cloud-based EV charging management systems, or both. The benefits of network connectivity include:

• Allowing EV owners to start, stop, and schedule charging remotely.

• Taking advantage of time-of-use tariffs to reduce charging costs.

• Providing real-time monitoring and management of the charging infrastructure.

Power Connection

EVSE units can connect to various power sources depending on their location and purpose:

• Level 1 Charging: This typically involves using standard 120-volt household outlets for residential charging.

• Level 2 Charging: Level 2 chargers are powered by 208- to 240-volt AC outlets. These chargers are commonly found in residential, workplaces, multi-family units, hotels, retail locations, and fleet charging installations. They can be hardwired directly into 240V household service or 208V commercial service.

• Multi-Charger Installations: Private and public multi-charger installations, often at Level 2 or DC fast chargers, are hardwired to electrical service infrastructure specifically designed for EVSE, which is connected to the electrical grid.

Ports and Cables

Ports are the receptacles on the EVSE housing to which cables attach. In some cases, cables are permanently connected to the housing. Cables serve as flexible conduits for the transmission of electricity, allowing the flow of power from the EVSE to the electric vehicle.

Connectors

Connectors are located at the other end of the car's charger and plug into the corresponding port on the electric vehicle. The type of connector used depends on several factors, including the level and type of charger, whether it outputs AC or DC power, the connector standard supported by the EVSE supplier or EV charging service provider, and regional differences. In North America, the most common connectors include the J1772, CCS (Combine Charging System), and the NACS (North American Charging Standard).

Common Features

EVSEs are designed to keep both the user and the electric vehicle (EV) safe during the recharging process. Here are some of the common features of an EVSE:

1. Auto Restart After Power Outage: EVSE units are equipped with an auto-restart feature that resumes charging after a power outage, ensuring a seamless charging experience.

2. Breakaway Safety Cable: A breakaway safety cable is included to protect the EV and prevent damage in case of unexpected disconnection.

3. Integrated Cable Storage: EVSE units often come with integrated cable storage, keeping charging cables organized and easily accessible.

4. Auto Short Circuit and Ground Fault Shut-off: Safety mechanisms automatically shut off power in the event of a short circuit or ground fault, reducing electrical hazards.

5. Ground Fault Monitor: The ground fault monitor eliminates the need for monthly user testing, ensuring consistent safety without manual intervention.

6. Power Sharing: EVSE units are designed to sense other large electrical loads in use within your home, pausing EV charging until the load subsides, preventing overloads.

7. Power and Charging Indicator Lights: Visual indicators, such as power and charging lights, provide users with essential information about the status of the charging session.

8. Regulated Electrical Current: EVSE units deliver regulated electrical current to ensure an optimal and safe charge, eliminating the need for manual adjustments.

9. Safety Lock-out Feature: A safety lock-out feature prevents electrical current from flowing when the charger is not properly connected to a vehicle, enhancing user safety.

10. Automatic Disconnect: In case of hardware fault, an automatic disconnect feature activates, shutting off power to prevent damage to the car's battery, electrical shorts, or fire hazards.

Most Common Types of EVSE

EVSE comes in various forms, each designed to meet different charging needs and scenarios. The most common types of EVSE include:

1. Level 1 (120V): Level 1 EVSE uses a standard household outlet (120V) and is the slowest form of charging. It is suitable for overnight charging at home or in situations where faster charging is not required.

2. Level 2 (240V): Level 2 EVSE operates at 240V and is the most common type of residential charging. It provides a faster charging rate than Level 1 and is commonly found at home charging stations and public charging points.

3. DC Fast Charging (DCFC): DC Fast Charging is the quickest charging option, providing high-voltage direct current (DC) power to the vehicle's batteries. It is mainly used for commercial charging stations and is ideal for EVs needing rapid recharge. However, frequent rapid charging is found to be a contributor to battery damage.

4. Wireless Charging: This innovative form of EVSE uses inductive or resonant technology to deliver energy efficiently to the vehicle without physical cables. It's a convenient option for home and public charging, as it eliminates the need to plug in the vehicle.

How does EVSE work?

Image courtesy of Circuit Digest

When the charging cable is plugged into the EV, the control module within the EVSE performs various checks and then manages the power delivery based on the type of charger being used—alternating current (AC) or direct current (DC).

1. Connector Analysis: When the charging cable is plugged into the EV, the control module analyzes the connectors on the plug to verify several critical aspects:

   • Proper Connection: It checks if the plug is correctly and securely connected to the vehicle's charging port to ensure a safe and reliable connection.

   • Vehicle Readiness: The control module ensures that the electric vehicle is ready to accept a charge. This can include checking that the vehicle's systems are prepared for charging and that there are no faults or issues that might prevent safe charging.

   • Station Status: The control module also checks the EVSE's operational status to confirm that it is in working order, with no faults or safety concerns.

2. Status Indication: After performing these checks, the control module typically provides status indications, often using color-coded lights or displays. When everything checks out, these indicators usually turn green, signifying that it's safe and ready to initiate the charging process.

3. Main Relay Activation: If all the checks are successful and the status indicators are green, the main relay within the EVSE is activated. This main relay controls the flow of electricity from the power source (such as the electrical grid) to the cable connected to the EV.

4. AC vs. DC Charging: The next steps in the charging process depend on whether you're using AC or DC charging:

   • AC Charging: In the case of AC charging, the EVSE supplies alternating current (AC) power to the EV. However, it's important to note that this power isn't directly used to charge the battery. Instead, it is directed to an onboard charging system within the electric vehicle. This onboard charger then converts the incoming AC power into direct current (DC) electricity, which is compatible with the vehicle's battery.

   • DC Charging: When using DC charging, the process is more direct. DC power is delivered directly to the vehicle's battery, bypassing the need for an onboard charger to convert the power. This direct route to the battery significantly speeds up the charging process, making it faster and more efficient, particularly with high-end Level 3 chargers.

5. Completion and Disconnection: Once the power has been supplied to the vehicle's charging system, the EV's battery begins to charge. The charging process continues until the battery reaches the desired level, or until the user decides to stop charging.

Once charging is complete or when you decide to disconnect, you can simply unplug the cable from the EVSE. The EV is now ready for use with a charged battery.

Why is EVSE Important?

EVSE plays a pivotal role in the widespread adoption of electric vehicles for several reasons:

1. Convenience: EVSE infrastructure makes it convenient for EV owners to charge their vehicles at home, at work, or in public places. This accessibility encourages more people to choose electric vehicles.

2. Range Confidence: A robust network of EVSE stations reduces range anxiety by ensuring that drivers can easily find charging points, especially during long journeys.

3. Energy Management: EVSE systems can incorporate smart charging and demand-response capabilities, allowing better control and management of electricity consumption.

4. Environmental Impact: EVSE enables cleaner and more sustainable transportation, contributing to the reduction of greenhouse gas emissions and air pollution.

5. Economic Benefits: The growth of the EVSE industry creates jobs, fosters innovation, and supports local economies.

FAQs

• Is an EVSE a charger?

  No, an EVSE is not a charger. While often referred to as a charger, an EVSE is the hardware that delivers electricity to an electric vehicle. The charger is typically onboard the EV and converts the incoming AC power to DC to charge the vehicle's battery.

• What does an EVSE actually do?

  An EVSE manages the safe and controlled transfer of electricity from a power source to an electric vehicle. It includes connectors, cables, and control systems to facilitate the charging process, ensuring that the EV's battery is charged efficiently and securely.

• What is the difference between an EV charger and EVSE?

  The key difference lies in their functions: an EV charger typically refers to the equipment on the electric vehicle itself responsible for converting AC power to DC power to charge the battery. In contrast, EVSE, or Electric Vehicle Supply Equipment, includes the infrastructure and connectors that provide electricity to the vehicle from an external power source, ensuring safe and efficient charging.

• What does EVSE stand for?

  EVSE stands for Electric Vehicle Supply Equipment, which refers to the equipment used to provide electric power to electric vehicles for charging. EVSE includes connectors, cables, control units, and communication systems that facilitate safe and controlled charging processes.