TEST ENGINEERING. KNOWLEDGE
What is needed to test megawatt charging (MCS) communication and signals?
Define the MCS connector, communication interface, EV or EVSE role and normative editions before selecting the test setup. For communication and signal testing, compatible instrumentation and released methods are needed; a high-power energy-transfer test additionally requires appropriately rated power equipment.
Test area and results
| Test area | What to define or record |
|---|---|
| Charging equipment | IEC 61851-23-3:2026. |
| Communication | ISO 15118-10 and ISO 15118-20 as referenced by the equipment standard. |
| Interface | Compatible MCS coupler and signal setup. |
| Power | Agreed voltage, current, load/source and protective separation. |
IEC 61851-23-3:2026 covers MCS supply equipment and refers digital communication to ISO 15118-10 and ISO 15118-20. Its published scope leaves bidirectional power flow under consideration. Record the agreed ISO 15118-20 amendment status as well. [1] IEC 61851-23-3:2026 [2] ISO 15118-20:2022/Amd 1:2026
A repeatable test workflow
- Freeze the interface stack. Record coupler, physical communication link, EVCC/SECC role, protocol editions and implemented services. Match these to the configured MCS test hardware and library release.
- Prove the communication baseline. Establish the link and a normal session before enabling a power test. Capture negotiation, authentication when applicable, requested limits and state transitions.
- Exercise coordinated signal changes. Vary one supported limit, locking state, temperature input or communication condition at a time. Observe how the DUT updates messages and the energy-transfer state.
- Extend to rated power conditions. When power transfer is part of the objective, use the specified source/load, cooling and protective separation. Compare requested, permitted and measured operating values.
- Verify shutdown and restart. Execute the configured interruption case, observe the defined safe transition and restore the initial state. Store trace and setup versions for regression.
Define the acceptance records
| Check | Evidence for the verdict |
|---|---|
| Stack compatibility | Physical interface, protocol service and edition are explicitly matched on both sides. |
| Limit coordination | The DUT response remains within the applicable negotiated and electrical limits throughout the executed transition. |
| Thermal response | A controlled temperature/cooling condition produces the specified limit update or stop, with correlated measurements. |
| Scope labelling | Signal-only, controller, power-transfer and any project-specific bidirectional results are labelled separately. |
Fault examples and diagnostic checks
Link up, service selection fails
Compare the offered services and amendment/profile assumptions before investigating the power path.
Power limit changes too late
Align thermal/signal input, message update and measured response; identify the first delayed transition.
Repeated-session failure
Check shutdown completion and reset of communication and locking states before starting the next session.
Practical tip. Keep a compatibility matrix for coupler, link, services, firmware and library versions. “MCS supported” alone is too broad to identify the executed test configuration.
Design a reproducible test case
Separate interface testing from high-power transfer
Write the test objective before selecting the power equipment. Communication and signal cases investigate the counterpart states, exchanged information and defined responses. An energy-transfer case additionally needs an appropriately rated and controlled electrical path. Name the interface, operating conditions and normative documents for each objective. The word megawatt in the system name does not mean that every test must transfer megawatt power, and a low-power protocol demonstration is not evidence for a high-power electrical requirement. Keep these scopes separate in the request, the configuration agreement and the resulting report.
Control the starting state and counterpart role
Identify whether the vehicle or station is the device under test and which partner the setup will simulate. Record the relevant connector and communication configuration, power equipment where used and the released software and library versions. Establish a normal sequence before introducing selected deviations. For a failed transition, retain the states and messages before the stop as well as the physical signals available for evaluation. A message-level diagnosis and an electrical-power diagnosis may need different measurements; decide those channels from the test question rather than recording only the final error code.
Prepare results that survive a configuration change
Give each case an identifier, stimulus, expected response and decision rule tied to the agreed requirement. Keep the executed operating point and measurement configuration with the traces. When a higher-power setup or another interface option is introduced, state which earlier communication evidence remains relevant and which electrical cases need their own execution. Avoid copying a pass label between operating points without reviewing the method. A useful report also identifies cases that were not executed and the reason, so a reader can see the difference between a deliberately limited demonstration and an incomplete qualification programme.
Example: a normal sequence followed by a selected deviation
An illustrative test plan begins with the agreed MCS counterpart establishing the expected communication sequence. The next case changes one supported signal or protocol condition and evaluates the device response. Record the actual stimulus and the first resulting transition. If power is part of the case, retain the measured electrical behaviour alongside the messages; otherwise describe the test as communication or signal testing. Repeat the unchanged baseline after the correction. This example supplies no universal voltage, current or response-time limit and does not imply that an interface-only setup qualifies the complete high-power system. The configured method and applicable requirements determine those values.
Questions about this test scope
Does IEC 61851-23-3:2026 establish bidirectional MCS requirements?
Its published scope states that bidirectional power-flow requirements remain under consideration. Identify any such project test separately.
Can I test MCS communication without megawatt power?
A compatible signal/controller setup can address communication cases. Power-transfer results require the corresponding rated electrical equipment and measurements.
Why record the ISO 15118-20 amendment?
The published 2026 amendment includes an MCS service and security changes. Test configuration and expected behaviour must identify the agreed amendment status.
Does MCS communication testing require full charging power?
Not for every communication objective. Decide whether the selected case needs actual energy transfer or a particular electrical operating condition. Record a communication-only scope explicitly and use appropriately configured power equipment when the requirement depends on measured power behaviour.
Can I reuse CCS test results for an MCS interface?
Review the actual interface, communication profile and applicable requirements rather than reusing the connector label. Some diagnostic methods may be useful across projects, but the MCS case needs its own documented configuration and executed evidence. State which earlier result supports which current test objective.
Sources and further reading
Technical content: comemso. Updated .