To specify a custom EV connector, define the electrical load, mating interface, operating environment, safety requirements, and assembly constraints before requesting a design or quotation. Then provide a manufacturer with drawings, expected duty cycle, cable details, and validation requirements so the proposed connector can be assessed against the complete system—not just its current rating. For machinery OEMs, the connector must also fit the equipment’s installation, service, and production processes. This guide provides a practical sequence for preparing that specification and discussing it with Onlink.
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First, identify what the connector connects and when it is used. An EV connector in an OEM electrical system may carry power to a vehicle subsystem, connect charging-related equipment, or combine power and signal circuits in one assembly. Its function determines which contacts, protections, and mechanical features need to be considered.
Describe the application in practical terms: equipment type, installation location, whether the connection is inside or outside an enclosure, and whether it is expected to be disconnected during routine service. Include a simple system diagram if available. This helps a supplier understand the surrounding circuit and identify interfaces that may affect connector design.
State whether the current is continuous, intermittent, or associated with short-duration peaks, and explain how the equipment operates during those periods. Include expected operating hours, connection cycles, and whether the connector may be energized during mating or unmating. Do not treat a peak value as a continuous rating; the supplier needs the actual duty profile to assess the design.
Document the maximum and nominal voltage, continuous and peak current, number of power circuits, and any auxiliary or communication circuits. Identify the type of current and the system’s grounding or isolation arrangement where relevant. If these details are not finalized, mark them as provisional rather than allowing a supplier to assume values.
Current capability depends on the complete configuration, including contact design, conductor size, termination, enclosure, and heat dissipation. Request that the supplier state the conditions behind any proposed rating, such as cable size, ambient temperature, and installation arrangement. Ratings from different products should not be compared unless their stated conditions are comparable.
A preliminary design brief might list 400 V DC nominal voltage and 200 A continuous current as example targets, not as recommended values for every EV application. If the equipment also has a short peak load, specify its magnitude and duration separately, such as 250 A for 10 seconds, only when that reflects the actual system profile. Replace placeholders with values confirmed by the electrical design and applicable system requirements.
Also identify polarity, keying, contact sequencing, and any need for high-voltage interlock or temperature monitoring. If the connector includes signal contacts, state their purpose, electrical limits, and whether they must mate before or after the power contacts. The system designer and supplier should confirm how these features work together in the intended circuit.
Provide the available envelope, mounting method, mating direction, and clearance needed for installation and service. Include a dimensional drawing or CAD model showing nearby components, cable exit direction, bend space, and access for tools. A connector that meets electrical requirements may still be unsuitable if operators cannot reach the latch or route the cable without strain.
Specify how the connector will be retained and released, whether it needs a latch, panel mounting, strain relief, or a defined handle orientation, and how accidental disconnection should be addressed. Describe expected mating frequency and who performs the operation. If the assembly is installed in machinery subject to vibration or movement, provide the relevant equipment-level requirements rather than relying on a general description.
State conductor material, cross-sectional area, insulation type, cable outside diameter, and the termination method if these are already selected. Clarify whether the supplier is expected to provide the connector alone, a cable assembly, or a fully integrated harness. These details affect fit, assembly method, and the space needed for routing and sealing.
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List the conditions at the connector location, including temperature range, moisture, dust, chemicals, cleaning agents, salt exposure, and outdoor or indoor use. A broad label such as “industrial environment” does not tell a supplier which materials, seals, or protective features to assess. Where possible, describe the actual exposure and the duration or frequency of contact.
As an example of a requirement format, an OEM might specify an operating range of -30 °C to +85 °C for a particular installation. This is an illustrative range only; it is not a universal EV connector requirement or a claim about a particular product. Confirm that any proposed material and assembly are suitable for the full set of system conditions, including storage and transport if those differ from operation.
Identify requirements for ingress protection, corrosion resistance, flammability, or chemical compatibility only where they apply to the equipment and its governing design criteria. Ask the supplier to explain what evidence or test method supports a proposed environmental claim. Do not infer a complete assembly’s performance from an individual material or component specification.
Share the relevant system architecture, interface drawings, and any applicable OEM or regulatory requirements. The connector supplier can help review the proposed interface, but the OEM remains responsible for determining which requirements apply to the finished equipment and confirming system-level compliance. Keep the requirement source and revision visible in the design package.
Explain how the connector will be assembled, inspected, and serviced. If the product is intended for a production line, specify installation tools, allowable assembly variation, labeling, traceability, packaging, and inspection criteria as applicable. These manufacturing details can affect the design just as much as the electrical interface.
A concise package makes a technical review more productive and reduces the risk of quoting against incomplete assumptions. Include a requirements table, system diagram, drawings or CAD files, and a list of open questions. Label each item as confirmed, provisional, or to be determined.
| Specification area | Information to provide | Why it matters |
|---|---|---|
| Electrical | Voltage, continuous and peak current, circuits, duty cycle, interlock or sensing needs | Defines contact and circuit requirements for review |
| Mechanical | Envelope, mounting, mating direction, retention, cable routing, service access | Checks fit and usability within the equipment |
| Environmental | Temperature, moisture, dust, chemicals, vibration, and exposure conditions | Guides material, sealing, and validation discussions |
| Production | Annual demand estimate, assembly method, inspection, packaging, and schedule targets | Supports manufacturing and sourcing review |
When comparing proposals, ask each supplier to identify assumptions, deviations, and unresolved requirements. Request the proposed drawing, materials, interface details, and stated operating conditions for any ratings. A quotation alone does not establish that the connector is suitable for the system.
Agree on validation before design release. Depending on the application, the OEM may need to evaluate fit, mating operation, electrical performance, temperature rise, environmental exposure, and mechanical durability. The test plan should reflect the actual product configuration and system conditions; avoid treating a generic test list as proof of compliance.
The most useful next step is to send Onlink your system requirements, interface drawing, expected operating profile, and target project timing. Our team can review the information with you, clarify gaps, and discuss whether a custom EV connector or cable assembly approach should be evaluated for your OEM electrical system. If some details are still open, identify them clearly so they can be resolved during the engineering discussion.
In short, specify the connector by documenting its electrical, mechanical, environmental, and production context, then verify the proposed design against the real equipment conditions. A clear requirement package gives both the OEM and manufacturer a stronger basis for design review, quotation, and validation planning. Contact Onlink to discuss your application and the information needed for an initial technical review.
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