What is EVSE A Comprehensive Guide to Electric Vehicle Supply ...

As electric vehicles (EVs) continue to proliferate, understanding the infrastructure that supports them, particularly Electric Vehicle Supply Equipment (EVSE), or charging stations, becomes crucial. This guide explains what EVSE is, how it works, and why it's essential for the transition to electric mobility.

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After learning about EVSE, take the next step to learn about EVSE test and measurement.

Jump to a section on this page:

• What is EVSE?
• Breakdown of EV Charger Components
• Operation and Connectivity of EVSE
• Cables and Connectors for EVSE
• EV Charging Standards: Importance and Key Guidelines
• Market and Technological Trends in EVSE
• Equipment Used for Testing EVSE Systems
• EVSE Glossary: Key Terms in EV Charging

What is EVSE?

Electric Vehicle Supply Equipment (EVSE) is the bridge that connects an electric vehicle to a power source, facilitating safe and efficient charging. They take electrical power from the grid and transfer it to an electric vehicle in order to charge the battery within the EV. They can go by different names like charging stations, EV chargers, or charge points.

Breakdown of EV Charger Components

The components of Electric Vehicle Supply Equipment (EVSE) are designed to move electrical power from the power grid to an electric vehicle safely and efficiently. Here's a closer look at the main components of an EVSE:

• Housing/Enclosure: This is the protective casing that contains all of the EVSE's internal components. It safeguards the electronics and electrical equipment from environmental factors, like rain or snow, and potential mechanical damage, like a car backing into them or vandals. The design can vary from simple wall-mounted boxes to sophisticated standalone units for public use.
• Power Input: This subsystem is responsible for connecting the EVSE to the electrical grid. It can handle various voltage and current levels, as well as phase configuration, depending on whether the EVSE is designed for Level 1, Level 2, or DC Fast Charging. Input electronics help control the impact of the EVSE on the grid, including conducted electromagnetic compatibility, harmonics, and power factor. 
• Control Electronics: These are the brains of the EVSE. They manage the charging process by communicating with the connected vehicle to ensure that the correct amount of power is delivered at the right speed. This is also where the electricity used is measured for billing the user. This system includes relays and switches that can interrupt power flow for safety.
• Cable and Connector: The cable extends from the housing and ends in a connector, which plugs into the electric vehicle. The design of the connector varies by the standards it supports (such as J, IEC , NACS, CCS, and CHAdemMO).  Some connectors support only AC charging (Level 1 and or Level 2) while others support DC fast charging. In addition to power transfer, cables and connectors must carry communications signals between the EVSE and EV.
• User Interface: Most EVSE includes a user interface, which can range from simple indicator lights to advanced touchscreens that display charging status, power usage, and other operational details. EVSE may also include network connectivity like Wi-Fi or Ethernet, allowing for billing, remote management, and updates. 
• Safety Mechanisms: Integral to all EVSEs are various safety features, such as circuit breakers, ground fault circuit interrupters or residual current device (GFCIs or RCDs), and thermal sensors, which help prevent overheating and electrical faults. Cables, connectors, and communication between the EVSE and the EV are designed for safe connection and charging sequencing. These systems ensure that the charging process is safe for both the vehicle and the user.

Together, these components form a complex system that plays a crucial role in the usability and safety of electric vehicle charging, providing a reliable bridge between the power grid and the vehicle.

Operation and Connectivity of EVSE

How EVSEs Operate:

Getting electrical power from the grid to an electric vehicle is all well and good, but as we saw above, EVSE is more complicated than a simple wire.  Let's break down a few different ways EVSE are different from each other.

Charging Levels and Specifications:

Charging levels in EVSE vary by power source and determine how fast a vehicle charges. The definition of the levels or types varies between regions. In North America, which uses 120 V single-phase voltage and 240 V split-phase voltage in residences, the following levels apply:

• Level 1 Charging: Utilizes standard 120 VAC household outlets for slow charging. This level of EVSE is closest to being a simple wire, but there are still safety mechanisms and occasionally control electronics present. Many of the components discussed above are excluded in Level 1 EVSE.
• Level 2 Charging: Employs a 208-240 VAC supply to deliver power to the vehicle faster, resulting in faster charging. Most residential and commercial spaces either have this level of voltage available already, or can be retro-fitted with minimal effort. This level of charging is currently the most common.
• DC Fast Charging: This level of EVSE is the most complex and involves converting AC electrical power to DC power before sending it to the vehicle while Levels 1 and 2 send AC power to the vehicle. This level typically uses higher voltage and current 3-phase power that is only available in commercial or industrial settings.

In countries that have single-phase 230 VAC receptacles throughout the power system, there is no equivalent to the North American Level 1. However, power levels roughly corresponding to Level 2 are typical in international AC systems, including some systems and EVs that can handle 3-phase AC.  All regions support some form of DC Fast Charging.

Note: The terms “Type 1” and “Type 2” are used to describe the pin configurations on EV power connectors.  These do not correspond directly to the “Level 1” and “Level 2” charging levels used in North America.

Power Connections:

EVSEs can be connected to the grid in several ways, tailored to different needs:

• Plug-in Connections: Typically used in homes and for emergency charging for their simplicity and convenience. In North America this is the standard for Level 1 charging.
• Hardwired Connections: Necessary for higher power requirements such as Level 2 or DC fast charging, these requires professional installation.

Safety, Testing, and Maintenance:

Maintaining the safety and efficiency of EVSE is critical, necessitating regular testing and maintenance.

• Inspections and Updates: Routine checks ensure that all electrical connections are secure, while firmware updates enhance functionality and safety.
• Physical Checks: Regular inspections help to detect and address wear and tear, preserving the integrity and safety of the equipment.

Connectivity Explained:

Modern EVSE leverages network connectivity to enhance both user experience and operational efficiency. Key features include:

• Remote Monitoring: Enables both users and service operators to monitor charging sessions and manage energy consumption from afar.
• Smartphone Control: Offers users the convenience to start, stop, and schedule charging via a smartphone application.
• Smart Home/Building Integration: Connects with home energy management systems to optimize electricity use, integrating smart features such as adaptive solar energy consumption.  Utilities may offer discounts in return for being able to throttle charging during periods of high demand.

Cables and Connectors for EVSE

The role of cables, and connectors in EVSE systems is crucial for ensuring the safe, efficient, and effective charging of electric vehicles. Here's a deeper look:

Cables

Engineered for durability and safety, charging cables need to handle significant currents while maintaining flexibility and standing up to heavy use.  Generally, their thickness varies by charging level, with thicker cables required to support higher amperage.

Connectors

Available in several types, connectors must match vehicle standards and are equipped with safety features like thermal sensors and locking mechanisms. Naturally, they need to mate with the matching port on the EV or be made compatible through an adapter.  The standard connectors are:

J (Type 1): Primarily used in North America for Level 1 and Level 2 charging.

IEC (Type 2): Used in Europe and integrated into CCS for DC fast charging. It can also handle 3-phase AC in certain electrical systems.

CHAdeMO: Japanese standard for DC fast charging, notable for its large size and for being one of the earliest connector standards.

CCS (Combined Charging System): Integrates AC and DC charging into a single connector, widely adopted in Europe and North America for fast charging. CCS1 uses the Type 1 connector with 2 added pins to carry DC current. CCS2 does the same but uses the Type 2 connector.

J (NACS): Previously a propriety standard from Tesla that is now available for broader use, this connector is being adopted by much of North America for the future. It is designed to handle all levels of charging.

EV Charging Standards: Importance and Key Guidelines

Introduction to EV Charging Standards

Electric Vehicle Charging Stations are vital components of the EV ecosystem, governed by standards that help to ensure safety, efficiency, and compatibility:

• Safety: Standards prevent overloading and electrical fires, ensuring that connections are secure before power is transmitted.
• Interoperability: Ensures different vehicle models can use various charging stations safely and without issues.
• Power quality standards and electrical codes:  These codes and standards regulate the connection to the electrical system and limit the allowable impact of charging stations on the grid – for example power factor and harmonics.

Major Standards Organizations

In addition to local electrical codes, several bodies develop and enforce standards for EVSE:

• IEC (International Electrotechnical Commission): Focuses on electrical systems, producing standards like IEC for electromagnetic compatibility, EVSE types and communications, as well as IEC for connectors.
• IEEE (Institute of Electrical and Electronics Engineers): Specializes in electronics and electrical engineering, setting guidelines for safety and technology integration.
• SAE (Society of Automotive Engineers): Develops standards for manufacturing and testing EV components, ensuring they meet rigorous automotive requirements.
• GB (National Standards of the People’s Republic of China): Develops standards for EVSE in China, such as GB/T .

The standards created by these bodies foster a reliable, safe, and user-friendly environment for electric vehicle charging, contributing to the broader adoption of EVs globally.

Learn More About EV Charging Standards

Market and Technological Trends in EVSE

The realm of Electric Vehicle Supply Equipment (EVSE) development is dominated by a few exciting technologies that promise to make EV charging more efficient and accessible:

• Enhanced Charging Speeds: Ongoing advancements are consistently aimed at reducing charging time, making it comparable to or faster than traditional fueling methods.
• Wireless Charging Developments: Steady progress in wireless charging technologies suggests a future where EVs can be charged effortlessly, eliminating the need for physical cables.

Predictions for Sustained Developments:

Seamless Integration with Renewable Resources: Future EVSE technologies are expected to harmonize more effectively with renewable energy, promoting environmental sustainability and reducing dependency on traditional power sources.

• Advancements in Smart Charging Capabilities: Innovations are likely to further refine the intelligence of charging systems, enabling them to adapt charging schedules based on real-time energy demand and pricing.
• Expansion of Vehicle-to-Grid (V2G) Systems: As V2G technology matures, it is anticipated to become more widespread, allowing EVs to contribute back to the power grid and enhance grid resilience.

These trends indicate a trajectory towards a more integrated, efficient, and user-centered EV charging infrastructure, continuously adapting to the evolving needs of the market and technology.

Equipment Used for Testing EVSE Systems

To ensure safety, reliability and efficiency, EVSE systems are rigorously tested during the design process, during manufacturing, and in the field. Here's an overview of the key types of test equipment used.

General Test and Measurement

During the design and manufacturing process, oscilloscopes, digital multimeters, signal generators, power supplies, electronic loads, and power analyzers are used to help bring up new designs and confirm that EVSE is operating within specifications.

Pictured in the image above:

• Oscilloscope (in the center): Utilized for visualizing and analyzing the waveforms of electrical signals within the EVSE. This can be used to ensure the proper functioning of the pilot signal between the vehicle and the charging station, to observe the quality of the power supply, and to check for any noise or interference that might affect the charging process.
• Arbitrary Function Generator (to the left of the oscilloscope): Used to simulate various signal conditions that the EVSE might encounter when interfacing with different electric vehicles. This device can help in stress-testing the EVSE’s response to irregular signals or to mimic vehicle communications for testing purposes.
• Source Measure Unit (SMU) (to the far left): Employed to accurately measure the electrical parameters such as voltage, current, and resistance in the EVSE modules and components. It ensures the output is within specified tolerances and that the charging station is safe and efficient. It may also be used for diagnostic purposes when troubleshooting EVSE faults.
• Power Supply (below the SMU): Provides a stable and adjustable source of power to emulate different charging conditions. A low wattage power supply, like the one shown, can be used to power modules and subsystems during testing. A high wattage supply such as an EA series bidirectional power supply can be used to emulate a vehicle's battery system for DC fast charging, or emulate abnormal conditions during development or testing.

These devices are used to simulate vehicle connections and assess the EVSE's response, verifying compliance with standards such as IEC and SAE J. They can check for correct signaling, timing, and the delivery of power.

• Functional testers and test adapters are used to simulate an EV connection to verify the EVSE's operational functions.
• Test adapters facilitate the connection of digital multimeters or oscilloscopes.
• Protocol analyzers check communication protocols to ensure compatibility with various vehicle models.

Network Connectivity Testers

These tools evaluate the EVSE's ability to communicate with remote monitoring systems, ensuring that features like smart charging and firmware updates function properly. The two main types of equipment used for testing connectivity are as follows:

• Network analyzers assess the ability of the EVSE to communicate with central systems.
• Wi-Fi testers ensure the reliability and security of wireless connectivity features.

Electrical Safety Analyzers

Critical for ensuring that the EVSE operates safely, these analyzers test protective mechanisms, grounding, insulation, and the presence of any potentially hazardous electrical faults. These generally fall into the following types:

• Insulation resistance testers measure the integrity of electrical insulation.
• Ground fault circuit testers detect faults in the grounding system to prevent electrical hazards.
• Power quality analyzers these instruments measure the impact of EVSE on the electrical grid, including voltage levels, current, frequency stability, power factor, and harmonics.

EVSE Glossary: Key Terms in EV Charging

If you’re living in a household of multiple EV owners or looking to the future where this may be the case, some planning will go a long way to ensure no one runs out of juice.

This guide offers an overview of the current options to keep every EV charged without sparking any tensions.

The primary methods for charging multiple EVs at home include:

1. Sharing a single charger.
2. Utilizing two.
3. Employing two with load management.
4. Implementing a multi-port charger.

Each method involves various approaches and a wide range of hardware solutions. Factors influencing your choice may include electricity supply type and capacity, Distribution Network Service Provider (DNSP) regulations, budget constraints, vehicle model, battery size, charging time, and individual priorities.

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1. Sharing A Single Charger

Admittedly, you likely started reading this article seeking more sophisticated solutions than simply taking turns with a single EV charger. However, this may be the only viable option for some households due to electricity supply constraints or DNSP rules.

If you’re stuck with being a single-charger household, it’s not the end of the world. Think of the money you’ll save on hardware.

Sharing is Caring

Everyday charging may not be necessary for every household member. Factors like battery size, charging times, and commuting distances will vary. Many families can successfully coordinate a sharing schedule, alternating usage on different days.

Maybe that doesn’t work for you. You’re rightly sick of jumping out of bed in the middle of the night and shuffling vehicles around to reach the charger. Considering there’s no standard for charge port locations on all the different EV models available, it doesn’t seem like a good long-term solution. There’s got to be a better way.

2. Using Two Chargers

Using Two Level 1 Chargers

When installing a second or even a first dedicated charger isn’t feasible, consider having an electrician install two 15A General Purpose Outlets (GPOs) in your home. This would enable you to plug in and use two Level 1 chargers simultaneously, with each operating on a separate circuit.

Opting for this solution can be quite effective, as a 15A GPO can accommodate up to 3.6kW. With two outlets, you’ll achieve a combined power of 7.2kW—comparable to most single-phase Level 2 chargers shared by two EVs.

Using A Level 2 Charger Plus Level 1 Charger

One option is to charge an EV using the dedicated Level 2 charger while the other vehicle uses the Level 1 device that came with it, plugged directly into a power outlet. Though the second vehicle experiences a slower charging rate, this setup allows for simultaneous charging of both vehicles.

Potential Pitfalls

The level 1 slow charger is not a smart device. It will draw whatever current the EV requests, and the only way to adjust the charge rate is via the car settings. This means the Level 1 charger could operate at near the full rating of a 10A or a 15A GPO the whole time it’s plugged in. This potentially strains the circuit which, unless you take a few precautions, can lead to problems. And surely it goes without saying, but I will anyway – never plug two into the same power outlet, or even the same circuit.

The other thing to consider – if you’re charging two EVs simultaneously, the current draw starts to add up. For most households running a level 1 and level 2 EV charger at the same time is not going to overload the main switch (yet), but add a few more high-powered appliances into the mix and it starts to look a little different.

For example, a single-phase level 2 charger is rated at 7.4kW (up to 32A). Add that to a level 1 charger running at full tilt on a 10A circuit (assume 10A). It’s now potentially at up to 42A just for EV charging. A typical single-phase main switch on a domestic switchboard in Australia is rated at 63A or 80A, so this could account for over half your electrical supply. You’re now at the point where you need to know what other power-hungry appliances are running, otherwise risk tripping circuit breakers.

Having a nice big rooftop solar array and charging your vehicles during the day can reduce grid demand substantially. But this is no panacea because the sun isn’t always shining, and electrons go where they want when they’re needed.  Even if your charger can be configured to only charge from excess solar energy, it is still capable of full charging power with no sun. Your electrical installation has to be up to the task for the worst-case scenario.

With a three-phase supply, spreading the load across all three phases is easier. It’s possible to have a single-phase level 2 charger installed on one phase, while other loads are balanced accordingly across the other phases. The downside is that a single-phase device could take longer to do the job than a 3-phase charger. Although it gives you more headroom on the other phases, it may not be the best option if fast charging one vehicle is your priority.

3. Using 2 Chargers With Load Management

OK, here’s the part you’ve been waiting for. If you own two electric vehicles, it makes sense to have two EV chargers right?

Yes, of course; however, the ramblings above (Potential Pitfalls) are now more important because you’ve upped the ante as far as potential loads on your switchboard and wiring. The number of EV chargers you can install is limited by the capacity of your electricity supply for all the reasons above. As always, your DNSP has the final say on this, based on Australian Standards and relevant State electricity regulations.

The clever people designing and building EV chargers have devised solutions to address maximum current limits on typical household supplies. Enter “load management”. They’ve worked out a way to keep your wiring and switchboard happy by using smart devices to manage the amount of current draw available to each unit, and to prevent overload of the system. This is generally done one of two ways:

Power Sharing

Some chargers can be configured to set a maximum power limit that is shared by all installed chargers. Power sharing (sometimes called load sharing) is achieved by using a smart device that communicates to all configured devices through Wi-Fi, Ethernet, or Open Charge Point Protocol (OCPP).

For example, if your main switch is rated at 63A, a limit of 40A could be set for 2 chargers to share, leaving 23A for household appliances. The user, however, would have to manually monitor the household loads and make sure they are under the threshold, otherwise risk overloading the main switch.

Dynamic Load Balancing

Other chargers use a feature called dynamic load balancing that takes additional loads into account as well. This is useful if you have no choice but to put a load of washing on while charging up the EVs.

Dynamic load balancing considers the electrical capacity of a household on a real-time basis. It adjusts the charging rate accordingly, ensuring it stays within the available power capacity at any particular time. Household loads are given priority. You can now sit back with a smile, knowing that your house won’t trip the main breaker now that you’ve relinquished control to a computer.

Some devices with dynamic load balancing can also interact with solar inverters, so they incorporate instantaneous rooftop solar energy into their algorithm.

Regardless of whether or not your EV chargers have any of the above smarts, in the case of multiple single-phase chargers it’s recommended to install them all on different phases if you have a three-phase supply, to spread the loads. If you are on a single-phase supply your options are more limited.

DIY Solutions

Home Assistant

For tech-savvy people with too much time on their hands – Home Assistant is an open-source home automation platform that allows you to control various smart devices, including EV chargers. It’s possible to control two EV chargers with the app and operate them one at a time or limit the current on each. To control two EV chargers with Home Assistant, you’ll need two compatible devices that support integration with either OCPP or Modbus protocol.

Once you have connected the chargers to your home network, you can integrate them into Home Assistant using the appropriate add-on. It’s possible to create automations or scripts that allow you to operate them one at a time or limit the current on each.

For example, you can create an automation that starts charging on one EV and then switches to the other once the first one is fully charged. You can also create scripts that allow you to set the charging current for each charger individually.

IFTTT

Another DIY solution is IFTTT (If This Then That), which is both a free web-based service and a mobile app that allows users to create and manage automated tasks. The app allows users to browse and enable pre-built applets, create their own applets using a simple drag-and-drop interface, and manage their connected services and (supported) devices.

If your EV chargers support power sharing, you may be able to use IFTTT in conjunction with a smart home automation platform to automate the process. For example, you could use IFTTT to trigger a smart plug or switch to turn off or reduce the power to other appliances in the house when the EV chargers are in use, ensuring enough power is available for both.

Third-Party Apps

An ever-growing range of third-party apps can be integrated with Home Assistant, IFTTT, or communicate directly with EV chargers and devices. These have varying levels of functionality based on supported hardware and communication protocol. Unfortunately, there’s no one-size fits all.

Some of them, although not designed specifically for charging multiple EVs, may help optimize your  experience: For example: Charge HQ, EV Energy, and Homeseer.

4. Use An EV Charger With Multiple Ports

Seemingly an obvious solution for charging two EVs is a device with two ports, so you can simply plug in any vehicle whenever you want.

As of the time of writing, sadly, there are no dual port EV chargers available designed specifically for homes, which are available from retailers in Australia. I guess there aren’t enough dual EV households here yet.

You can still buy a dual-port EV charger designed primarily for commercial and public use. It might not be the most cost-effective solution, but as long as you comply with your DNSP regulations, and have sufficient electrical supply infrastructure, nothing is stopping you from installing one in your home.

Which EV Charger Is Best For My Growing EV Collection?

I can’t tell you that. I can, however, point you to our EV Charger Comparison Table where you can compare prices and specifications side-by-side and see what solutions may be best for your situation and budget.

Also check out another SQ article – Best EV Chargers : According To Australian Installers. All top 3 chargers on this list can be configured to suit multi-EV households, although they may need additional hardware.

Hopefully I’ve given you enough information to make a decision that’s right for your circumstances.

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