What are the communication protocols in electric vehicles?

Electric vehicles (EVs) are reshaping the automotive industry in terms of sustainability and technology. EVs are not only reducing greenhouse gases and dependence on fossil fuels, they are also driving innovation in aerodynamics, lightweight materials, batteries, powertrains, inverters, software, advanced driver assistance systems (ADAS ), charging systems, cables and more. more.

There have also been advances in vehicle efficiency, range and costs, with more drivers than ever considering making the switch and leaving their conventional fuel-powered vehicles behind. While much of this decision often comes down to battery life and range, an equally important innovation is the vehicle’s “communication” capability.

In fact, much of an EV's ability to function – from driving to charging – depends on its electronic communication protocols.

Several communication standards are used in EVs or for vehicle charging, including:

• Most EVs rely on the Controller Area Network (CAN) protocol for communication between vehicle components and external systems.
• The Modbus and Local Interconnect Network (LIN) protocols are used by some auxiliary vehicle components that do not require real-time data communication.
• Protocols like CHAdeMO and CCS play a crucial role in fast charging.
• ISO15118 enables bi-directional charging and vehicle-to-grid (V2G) integration.
• Ethernet is a complete solution for all high-bandwidth data communications such as video streaming, infotainment systems and ADAS in electric vehicles.
• Wi-Fi and Bluetooth enable integration of smartphones or devices into EVs

Let's review these communication patterns in more detail.

Controller Area Network (CAN)
CAN is the main communication protocol used in most vehicles. Nearly all North American and European automotive manufacturers (70% globally) rely on CAN bus technology for engine management, safety systems and comfort features. Almost all luxury and premium vehicles have fully integrated CAN systems, and only a few economy models still feature LIN or multiplexing.

CAN is the communication backbone of all modern vehicles. It allows multiple electronic control units (ECUs) – such as the engine, airbag and ABS control units – to “talk” to each other in real time, sharing essential information to keep the vehicle running smoothly and safely. It is also used in other industries, including aviation, aerospace, medical and industrial automation, mainly because it is cost-effective, reliable and scalable.

A CAN bus uses just two wires and exchanges data in small, prioritized messages, ensuring that critical information such as brake or airbag signals are not delayed. CAN relies on carrier sense multiple access with collision detection (CSMA/CD), which allows devices to take turns transmitting, detecting, and resolving collisions to ensure message delivery. The protocol has integrated mechanisms that guarantee data integrity and message reliability.

As with conventional fuel-powered vehicles, CAN in EVs facilitates communication between ECUs, including the control unit (EVCU), engine controller, battery management system (BMS), and other vital components. These systems continuously exchange data such as battery voltage, current, temperature, engine speed and torque demands.

For example, CAN provides a vital link between the BMS and other systems in EVs. The BMS monitors battery health, temperature and remaining charge, communicating this information to the EVCU and driver via the CAN bus. This bus also facilitates communication between the battery, cooling system and EVCU, helping to manage battery temperature.

CAN also allows other safety features, such as regenerative braking, traction control and electronic stability control, to work effectively. The bus allows real-time communication between the brake system and the engine controller to apply regenerative braking.

CAN is also essential for communication between EVs and charging stations and is used by other protocols (such as IEC 61851) for power supply control, handshaking and safety checks during charging. New smart grid technologies, such as V2G, also use the bus to communicate between the EV and the grid. With its help, EVs optimize energy use and intelligently regulate their charging and discharging in response to grid demand.

ISO 15118
ISO 15118 is an international standard that addresses communication between EVs and charging infrastructure, enabling bidirectional power transfer and smart charging capabilities. The objective is to improve safety, speed up the charging process and encourage the integration of the electric vehicle network.

By establishing a standardized interface, ISO 15118 also improves interoperability between manufacturers and charging stations. The standard incorporates two main components – the electric vehicle communications controller (EVCC) and the fueling equipment communications controller (SECC). The EVCC is the controller inside the vehicle that controls communication with the charging station. SECC is the charging station controller responsible for communicating with the EV.

Using the standard, EVs can receive power and send it back to the grid (V2G), supporting grid stability and energy management. ISO 15118 also helps you adjust billing based on network conditions, user preferences and energy tariffs, optimizing energy usage and costs. Additionally, the protocol supports automatic authentication and payment using digital certificates, eliminating the need for RFID cards or manual interactions. The protocol uses TLS and digital signatures to ensure data privacy and integrity, protecting against unauthorized access or tampering.

Currently, ISO 15118 is still evolving, with new features and improvements being added, so its use has been limited in the production of EVs. However, this standard is expected to become the de facto standard for electric vehicle charging and grid integration. It will likely incorporate wireless charging and advanced power management features in the future.

CHAdeMO
CHAdeMO, “CHArging deMO”, is a fast charging standard developed in Japan for EVs. It supports alternating current (AC) and direct current (DC) charging, allowing you to quickly charge your vehicle. Compared to widespread AC charging at public stations or at home, it uses a unique direct current (DC) method that charges batteries exceptionally quickly.

While many stations already operate at around 50 kW, CHAdeMO can supply up to 500 kW of electricity. This means an EV's battery can be charged to 80% in just 30 minutes, rather than the typical four to eight hours with AC charging. CHAdeMO is a fast charging standard and contains V2G (vehicle-to-grid) capabilities.

CHAdeMO has been widely adopted in Japan, China and South Korea. The standard faces competition from the well-established CCS standard in Europe and North America. CHAdeMO is unlikely to be adopted on a large scale in North America. In Europe, the standard is promoted through partnerships and pilot projects, but CCS still maintains the advantage.

Combined Charging System (CCS)
CCS is a standardized fast charging protocol prevalent in North America and Europe. It uses a unique dual-port connector to accommodate AC and DC charging plugs. A CCS-equipped EV can access any compatible charging station regardless of its power capabilities, supporting power levels ranging from 20 to over 350 kW depending on the specific implementation. Higher power levels facilitate accelerated charging durations and the establishment of ultra-fast charging infrastructures.

CCS relies on standardized communication protocols between an EV and the charging station. These protocols include:

• ISO 15118 – for V2G communication
• IEC 61851 – for charging station communication
• Open Charge Point Protocol (OCPP) – to manage communication between charging stations and central management systems
• TCP/IP – for internet communication and data exchange between an EV and the charging station during authentication, charging and monitoring
• WebSocket – for full-duplex communication between EV and charging station

The current AC charging infrastructure can be used with the CCS standard due to its backwards compatibility. This implies that Type 2 AC charging stations are still compatible with CCS-equipped vehicles. Backward compatibility eases the transition to CCS, enabling gradual integration of high-power DC fast charging infrastructure.

Modbus
Although Modbus is an industrial communication protocol, its application extends to EVs. Where the CAN bus is used for data communication between vehicle components, Modbus is used for communication between specific modules such as auxiliary power units, cooling systems or battery heaters.

Modbus offers a simple and cost-effective solution for integrating legacy components with newer systems. The protocol provides a straightforward way to access and analyze data for performance evaluation and troubleshooting. It has become widely used by automotive engineers to connect test equipment or diagnostic tools to specific components in EV prototypes. Many aftermarket modifications or add-ons for EVs (such as custom charging systems, battery monitoring gauges, or performance diagnostic tools) also use Modbus to communicate with a vehicle's existing systems.

One benefit of Modbus is that it provides reliable communication over long distances. Electric tractors, construction equipment or heavy trucks can rely on Modbus to communicate with external devices such as diagnostic tools, load management systems or specialized accessories. Overall, the protocol has only a marginal role in EVs compared to the CAN bus. Modbus is limited to older components, specialized applications, research and development, and aftermarket modifications. The CAN bus remains the predominant standard for most communications and internal functionality in an EV.

Local Interconnection Network (LIN)
LIN is a simple serial communication protocol for low-cost data exchange between low-power microcontrollers in vehicles. Although CAN continues to be the main communication standard for EVs, LIN plays a supporting role, serving basic functions and legacy systems.

In conventional cars, the LIN controls locks, windows, mirrors, seats and interior lighting and sends commands to the heating, ventilation and air conditioning systems. The instrument cluster uses LIN to communicate information related to fuel level, speed, warning lights, and basic sensor data such as coolant temperature or air pressure. In EVs, the LIN has a limited role.

Older EV models used LIN to communicate between subsystems such as seat controls, window mechanisms, and interior lighting. Because this protocol is only suitable for low-speed applications, it is used by non-critical EV systems such as auxiliary power units, battery heaters, or charging port communication. LIN is ideal for tasks that do not require real-time communication. Some aftermarket add-ons or modifications to EVs, such as custom lighting systems, battery monitoring gauges, or performance diagnostic tools, also depend on the LIN.

Ethernet
Ethernet is a prominent technology in computer networks, increasingly present in EVs. Ethernet provides significantly greater bandwidth than any automotive protocol, including CAN. It's excellent at handling large amounts of data faster, making its high-speed and bandwidth capabilities ideal for EVs.

ADASs use Ethernet to analyze more data in real time, leading to more accurate environmental mapping and smoother vehicle operation. It facilitates the exchange of data between cameras, radars and other sensors, allowing immediate responses to avoid collisions, lane departure warning and adaptive cruise control. Ethernet supports data exchange between the BMS, electric motors and other components for real-time analysis of battery health and performance, which helps maximize efficiency and minimize charging times.

Ethernet also works in V2X (vehicle-to-everything) communication. It enables car-to-car and car-to-infrastructure communication, allowing EVs to share information about traffic conditions, charging stations and road hazards, optimizing traffic flow and reducing accidents. The standard is used as a physical layer protocol in V2G communication and bidirectional charging.

Ethernet facilitates all over-the-air (OTA) updates for multiple EV systems. It is also used for car-to-cloud communication for remote diagnostics, traffic updates, and emergency response. This allows real-time assessment of EV performance and early detection of potential problems.

As in conventional vehicles, Ethernet in electric vehicles is used by infotainment systems for high-resolution video streaming, faster Internet connectivity and over-the-air updates. All high-speed data exchange between the BMS, electric motors and other components in electric and hybrid vehicles is managed over Ethernet.

Bluetooth and Wi-Fi
Bluetooth and Wi-Fi are wireless protocols that facilitate communication between EVs and external devices such as smartphones. Bluetooth is used for keyless vehicle entry and starting and remote vehicle locking or unlocking. Many OBD-II scanners connect via Bluetooth, allowing you to access basic engine and battery information via your phone or tablet.

Bluetooth also connects your smartphone to your vehicle for safe and convenient hands-free calling while you drive. It lets you stream music, podcasts, and audiobooks from your phone to your vehicle's audio system.

Wi-Fi is typically used to download and install software updates (OTA) for the EV, ensuring access to the latest features and bug fixes without visiting a dealership. Thanks to in-vehicle Wi-Fi, passengers can surf the web, stream movies and stay connected while driving. Future EVs can also potentially interchange with other vehicles and infrastructure to improve traffic flow, safety features and grid integration.

Conclusion
The successful integration of EVs into the automotive landscape relies heavily on efficient and standardized communication protocols. From the Controller Area Network (CAN) to the innovative two-way communication of ISO 15118 and the high-power charging capabilities of CHAdeMO and CCS, these protocols collectively contribute to the continued operation and evolution of EVs.

As technology continues to advance, the role of communication protocols in electric vehicles will undoubtedly expand, further improving performance, interoperability and the overall driving experience.