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Charging Technology

The Ultimate Guide to Test OCPP Chargers


August 21, 2023

The Open Charge Point Protocol, often shortened to OCPP, is a vital component in the infrastructure of electric vehicle (EV) charging. 

As a universal protocol, OCPP makes seamless communication possible between different EV charging stations and their corresponding backend system software. This compatibility feature enables a wide array of charging stations and systems to interact and cooperate effectively.

The benefits of implementing OCPP are vast and have a big impact on EV charging. OCPP adoption:

  • increases flexibility for operators, 
  • facilitates the interchange of network providers without the need for hardware alterations, 
  • stimulates innovation and competition in the market. 

This environment of continuous improvement directly contributes to advancements in technology and service quality. The end result? A hassle-free and streamlined experience for users of electric vehicles and fleet managers.

In this article, our focus will be on the practical facets of OCPP, particularly in relation to testing and identifying potential issues in EV charging systems. 

We look into common issues and problems, their solutions, and key operational elements such as boot notifications, heartbeat, and authorization requests. Learn more about OCPP and smart charging in our OCPP Report.

What is OCPP?

The Open Charge Point Protocol (OCPP) is a standardized communication framework widely utilized in the Electric Vehicle Supply Equipment (EVSE) industry. This protocol allows different hardware and software systems to communicate efficiently, making it the lingua franca of the EV charging environment.

The OCPP operates like a shared language, ensuring both the sending and receiving ends understand the information being communicated. This protocol, like any language, has rules and structures that guide the communication process, ensuring mutual understanding and efficient information transfer.

The protocol employs a mechanism called a Websocket to facilitate this communication between the hardware (the charger) and the backend system (the EV charging network software). This connection is initiated by the hardware, which sends specific information, including a secret and a charger ID, to the backend system. 

The backend system validates this information and completes the handshake, accepting the connection. Once this connection is established, messages can be sent and received by both the client end and the backend.

In case of disconnection, either intentionally or accidentally, both sides can reconnect, ensuring a flexible and resilient communication system. The entire connection process requires just a single URL, the Websocket URL.

Depending on the hardware manufacturer, there are several ways to update this Websocket URL. The update could be done remotely via an app, locally via a TCP connection, or by sending the URL to the hardware manufacturer's backend for updating. Some manufacturers may even allow direct access to their system for URL updates.

Smart charging software system Ampcontrol has a simple three-step process to connect your charger with a URL. 

Why is Hardware Testing Important?

The importance of EV charging hardware testing lies in its ability to identify potential faults and ensure the compatibility of charging stations before they are fully operational, thus guaranteeing an efficient and reliable charging experience for EV users.

  • Prevention of Charging Failures: EV charging failures can lead to significant inconveniences and inefficiencies for EV owners and fleets. If a charger fails during a charging session, it can cause an interruption in the power supply, leading to incomplete charging. Despite the essential role of the OCPP, many charger errors are unrelated to the protocol. Any connection point can potentially fail and should be tested. This includes connections from smart charge meters, base load information, real-time energy prices from utilities, and the physical connection of the vehicle to the charger.
  • Mitigation of Compatibility Issues: One major concern in the EV charging industry is compatibility. With the advent of different charging technologies and standards, ensuring a charger is compatible with various vehicle types and models is crucial. Hardware testing helps to ascertain whether a charger is universally compatible or if it is best suited to specific makes or models of EVs. In addition, it verifies that the charger can support different charging standards, such as OCPP 1.6J, further ensuring its interoperability with various EVs.
  • Importance for Complex Sites: Hardware testing becomes increasingly important for complex sites with multiple chargers. The level of interoperability needed for these sites is higher as they have to cater to a wider range of EVs. Moreover, if one charger fails at a large site, it can potentially disrupt the entire network, leading to widespread charging failures. Hence, thorough hardware testing is necessary to ensure the robustness and reliability of all the charging units at such sites. While the use of OCPP is standardized, the extent of its implementation varies between hardware manufacturers. For complex sites, it's important to ensure that all incoming data points are received correctly for the system to work as expected.
  • Ensuring Optimal Performance: Lastly, hardware testing is integral to ensuring the optimal performance of EV chargers. It allows for the identification and rectification of potential issues such as overcurrent, undercurrent, overvoltage, undervoltage, and temperature rise, thereby ensuring the safety, reliability, and longevity of the charging hardware.

Understanding Connection Issues

During the process of onsite testing for EV chargers, maintaining stable connectivity is crucial. A continuous communication between the EV charger and the backend system allows for smooth operations and efficient charging. One of the vital elements of this connectivity is the 'heartbeat' function within the OCPP acting as a lifeline for the network.

The heartbeat function is essentially the periodic message sent from the EV charger to the backend system, indicating the charger's online status. It establishes that the charger is active, functioning correctly, and ready to exchange messages. This process is continuous and is run at set intervals, ensuring real-time updates of the charger's status. Any interruption in the heartbeat can signal a potential issue with the charger or the network, making it a fundamental tool for identifying connectivity issues.

Incorrect Charger ID or serial number configuration

Despite the importance of a stable heartbeat, connection issues can still occur during onsite testing. One of the most common problems involves the incorrect configuration of Charger IDs or serial numbers. These unique identifiers are essential for distinguishing chargers in the network, and any discrepancy can result in connection errors. These identifiers must be correctly set during the initial charger configuration and verified before starting the test procedures.

Lack of TLS

Another common issue is the lack of Transport Layer Security (TLS), which protects the data being transmitted over the network. Without TLS, data can be intercepted, leading to potential unauthorized access or tampering. Incorporating TLS into the OCPP testing process ensures that the data exchanged between the charger and backend system is secure, maintaining the integrity of the testing procedures.

Timely troubleshooting of these issues is necessary to avoid disruptions in the testing process. Effective troubleshooting strategies involve verifying the charger IDs or serial numbers, ensuring the heartbeat is functioning correctly, and checking that TLS has been appropriately incorporated. 

High Latency

Another connection challenge could be high latency, which could disrupt synchronization and affect the real-time monitoring of charge sessions. Instances of latency up to five minutes have been reported, which can severely impact operations if left unchecked.

Charger Configuration Challenges

Setting up chargers correctly is key to efficient, user-friendly operations. This involves a host of considerations, including power parameters, charger type identification, authorisation requests, and authentication methods.

  • Set the correct power parameters – Ensure that the charger is programmed to deliver the appropriate current, power factor, and voltage to the EV. It's vital to note that different EVs have different charging capabilities, and the charger must align with these to avoid damaging the vehicle's battery or charging system. Additionally, these power parameters need to be configurable and adaptable to different situations, such as power limitations during peak demand times, to ensure grid stability.
  • Identify different charger types – With a range of charging hardware in the market, from AC Level 1 and 2 chargers to high-speed DC chargers, each comes with its own unique specifications and operational requirements. Understanding these nuances is vital to ensure that the charger operates efficiently and reliably, providing the required power and speed of charging for the user's needs.
  • Check OCPP configuration – OCPP configuration should be outlined in the documentation of each hardware manufacturer. These configurations might differ slightly, affecting how specific functionalities work or are interpreted. This variability could lead to discrepancies across chargers, causing confusion for those implementing or managing these devices. For instance, a commonly encountered issue is the “off enabled” configuration. Unaware operators might assume they have backend authorizations enabled, but if this configuration isn’t set to true, they could inadvertently offer free charging to any users, which is far from ideal.
  • Check update functionalities – For example, diagnostic firmware updates or firmware status updates, may not be fully implemented. While not critical, these functionalities can provide valuable information for operators, making their absence a potential hurdle. To avoid complications, operators need to test whether these functionalities are accessible.
  • Authorisation requests – These are the gatekeepers of an EV charging system. Authorisation requests are a security measure that ensures only authorized personnel or users can initiate charging sessions. This is particularly important for public and semi-public charging stations, preventing misuse or vandalism. Proper configuration of authorisation requests not only safeguards the hardware but also ensures that energy usage is correctly attributed and billed to the appropriate user.
  • Authentication process – This typically involves using Radio Frequency Identification (RFID) or vehicle identification numbers (VIDs). RFID provides a means for users to authenticate themselves at charging stations, linking back to a registered account for billing purposes. Meanwhile, VIDs ensure that the charging station correctly identifies the vehicle, adjusting charging parameters to the vehicle's specific requirements.
  • Processing of TX profilesTX profiles are the core of smart charging and can pose potential issues if they are not processed correctly. These profiles limit the charge based on various elements. If there's a limit to the number of profiles that can be sent at once or stored, this can restrict the functionality of the charge management system (CMS).

Understanding Power Profiles

An essential aspect of testing OCPP chargers involves understanding power profiles. These are crucial configurations that decide how chargers interpret power and current information from an EV. 

Power profiles allow the charging station to communicate with the vehicle's onboard charging system, ensuring the flow of electricity aligns with the vehicle's capabilities and charging needs.

The power profile is defined by transaction meter values. These values establish the rate at which energy is transferred during a charging session. It's essential to ensure these meter values are correctly configured according to the EV's specifications and the capacity of the charging station. If they are misconfigured, the charger may deliver too much or too little power, leading to longer charging times or, worse, potential harm to the vehicle's battery.

Correctly configuring transaction meter values allows the charger to operate smoothly, providing a seamless charging experience for the user. Accurate power profiles prevent possible discrepancies or disruptions in the charging process, promoting reliable and efficient EV charging.

Default Profiles and Their Behavior

Default profiles, an inherent aspect of an OCPP charger, dictate how the charger behaves under standard conditions. These profiles encompass parameters like maximum power delivery, response to charging requests, and idle behavior. They are designed to match the charger's capabilities with the typical requirements of EVs it is likely to service.

Understanding the standard behavior of these default profiles is crucial to ensure that they perform optimally during charging sessions. A misinterpretation of the behavior of default profiles can lead to erroneous operations, affecting the charger's performance, or worse, causing a fault in the system. This can be detrimental, especially in a public charging environment where a wide variety of EVs might rely on these default profiles for their charging needs.

Some common misconceptions about default profiles include the belief that they can't be altered or that they represent the maximum capabilities of the charger. In reality, these profiles can often be configured to better serve the requirements of specific EV models or charging environments.


Testing OCPP chargers is a crucial element in the smooth operation of EV charging systems. A thorough understanding of the OCPP and its intricacies significantly contributes to the accuracy and efficiency of these tests, leading to better-performing charging stations.

This guide aimed to shed light on various aspects of OCPP charger testing, from setting up onsite tests to understanding power profiles and common errors. It highlighted the importance of stable connectivity, proper charger configuration, and an in-depth understanding of default and power profiles.

We hope that the insights shared in this guide will prove valuable in enhancing your own testing processes. By embracing the principles outlined here, you can strive towards more accurate and efficient testing of OCPP chargers, ultimately contributing to the broader goal of effective and reliable EV charging infrastructure.

Ampcontrol is a leading smart charging software system that makes it easy to manage your EV charging and run extensive tests on OCPP chargers. To find out more, contact us today to book a demo.

Read the OCPP Report
OCPP Chargers, TX Profiles, OCPP 1.6J
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