When purchasing a battery cable assembly, specifying cable size, length and connector type is only the starting point. Buyers also need to define how the connections will be manufactured, inspected and documented.
A clear RFQ helps procurement, engineering and quality teams agree on what “acceptable” means before production begins. Here are five areas to cover when selecting a BESS harness supplier.
1. Request Evidence of Wire and Terminal Compatibility
A terminal’s nominal wire-size range does not provide all the information needed to approve an assembly.
Ask the supplier to identify:
- Conductor material, cross-section and strand construction.
- Cable insulation diameter and stripping requirements.
- Terminal manufacturer, part number, material and plating.
- Connector housing, seal and mating component, where applicable.
- Applicable terminal assembly instructions and tooling.
TE Connectivity’s crimp quality guidance identifies correct wire, terminal and tooling selection as a foundation of a good crimp. Its guidance also directs users to the relevant application specification for crimp-height tolerances.
For high-current battery connections, also confirm lug dimensions, terminal orientation and installation clearances. For control and auxiliary harnesses, confirm pin assignments, contact selection and any shielding requirements.
RFQ wording: “Please identify the proposed cable, terminal and tooling combination, including supporting application specifications and any deviations requiring approval.”
2. Define Crimp Process and Inspection Requirements
“Good crimp quality” is too general to serve as an acceptance requirement.
Request a product-specific inspection plan covering wire preparation, conductor insertion, terminal condition and applicable crimp dimensions. The supplier should explain how tooling setup, wear and production changes are controlled.
Where relevant to the terminal design, agree on crimp-height measurement, pull testing and cross-section inspection. These methods provide different information. TE notes that a connection passing a pull-out test may still have weaknesses that the test does not reveal.
Separate routine production checks from destructive sampling and initial process validation. Specify the inspection frequency, record format and response to a failed result.
RFQ wording: “Please submit the proposed crimp inspection plan, stating inspection methods, sampling frequency, acceptance references and nonconformance controls.”
3. Select Electrical and Mechanical Validation by Application
Battery power cables and low-voltage control harnesses do not need identical validation plans.
Use the assembly’s operating conditions and failure risks to select appropriate checks.
| Verification area | What the RFQ should clarify |
|---|---|
| Continuity and wiring | Approved pinout, polarity and detection of open or incorrect connections |
| Connection resistance | Measurement points, method, temperature conditions and acceptance limits |
| Insulation resistance or dielectric withstand | Applicability, test conditions and protection of connected electronics |
| Current and temperature rise | Load profile, installation arrangement, ambient conditions and measurement locations |
| Mechanical strength | Pull-test method, sample preparation and applicable limits |
| Environmental durability | Whether thermal cycling, vibration, humidity or other exposure is required |
This table is a planning checklist, not a mandatory test package for every harness.
For each selected test, identify the governing product specification or agreed procedure, sample quantity and pass/fail criteria. Qualification reports should match the proposed assembly configuration, with differences reviewed by engineering.
Avoid requesting “all standard tests” without defining which standards and requirements apply.
4. Make Batch Traceability Part of Delivery
Traceability should connect the delivered harness to its materials, manufacturing records and inspection results.
Agree on the identification level needed for the project: individual assembly, production batch or another defined grouping.
Request records linking the relevant identifiers to:
- Cable and terminal material lots.
- Assembly part number and drawing revision.
- Production date or batch.
- Relevant process and inspection records.
- Approved deviations and rework, where applicable.
Also specify label content, placement and durability requirements. Labels should remain readable under the intended installation and service conditions.
RFQ wording: “Please describe the traceability system and identify which material, production and inspection records will be supplied or retained, including the retention period.”
5. Control Drawings, Substitutions and Handover Records
An approved sample does not automatically cover later material or process changes.
Before ordering, establish the approved drawing revision, bill of materials and rules for substitutions. Define which changes require customer review and whether additional validation is necessary.
The delivery package should contain the agreed documents, such as approved drawings, inspection reports, material information, traceability details and installation instructions.
For bolted connections, obtain tightening requirements from the responsible equipment or terminal manufacturer. A factory crimp inspection does not verify a bolted joint completed during installation.
RFQ wording: “Changes to approved materials, terminals, tooling or assembly design must follow the agreed change-control process before implementation.”
Ask for Evidence That Matches Your Assembly
Electrical connection reliability is easier to assess when requirements are specific and records relate to the product being purchased.
When discussing battery connection, high-current, control or auxiliary harnesses with Winpower, provide your drawings, operating conditions and required acceptance documents. Ask which supporting records are available for the proposed assembly and agree on any additional validation before production.
A useful RFQ turns “reliable connection” into defined requirements, reviewable evidence and clear responsibilities.
Post time: Nov-05-2026