EV Battery Pack End-of-Line Test Checklist

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14 critical items still open - these are the highest-risk gaps.

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Safety and test setup

Operators are trained and authorised for high voltage workCRITICALTest area is barriered with signage and an emergency stop within reachCRITICALInsulated PPE and tools are inspected and in dateCRITICALTest equipment calibration labels are valid and recordedPack is identified by serial number before connectionLockout and discharge procedure is available at the stationFire response and thermal event plan is posted

High voltage electrical tests

Insulation resistance measured between HV terminals and chassis at the specified test voltageCRITICALDielectric withstand test performed if the control plan requires itCRITICALProtective earth or equipotential bonding resistance verifiedPack open-circuit voltage within specified rangeCRITICALContactor and pre-charge function verifiedHigh voltage interlock loop (HVIL) continuity verifiedCRITICALMain fuse or disconnect continuity checkedResults are compared with limits and stored

BMS and communication

BMS powers up and communicates on the expected CAN or bus addressCRITICALFirmware and calibration version match the released buildCRITICALAll cell voltage channels read and are within the allowed spreadAll temperature sensor channels read plausiblyCurrent sensor offset checked at zero currentState of charge initialised to the specified valueNo active or stored fault codes remain; test faults clearedBalancing function checked as per procedure

Enclosure, cooling and mechanical

Enclosure leak test passed at the specified method and pressureCRITICALCooling circuit leak and flow test passedCRITICALBusbar and terminal fasteners torque-verified with recorded valuesCRITICALSeals, gaskets and vents inspected for position and damageConnectors fully seated with locks engagedVisual inspection for dents, scratches and contamination completePack weight within tolerance

Traceability and release

Pack serial linked to cell lot, module and BMS serial numbersCRITICALTest results uploaded to the MES or quality system automaticallyFailed packs are tagged, segregated and entered in the nonconformance processCRITICALRework retest is a full retest, not a partial oneLabel content and barcode verified against the customer specificationPackaging and transport requirements for dangerous goods checkedRelease signed by authorised quality person

Critical items must all pass before a pack is shipped. This is a general starting list. Test voltages, limits and methods come from your customer specification and control plan.

EOL data to ERP traceability

Optional: we can discuss how pack test data could be linked to lots and serial numbers in your ERP.

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How to use the checklist

Work through each group with the test engineer and the quality engineer. Mark each item as done, and use the critical items as a gate. Add or remove items to match the customer specification and the pack design, and record the actual limits next to each one in your control plan. Export the completed checklist to PDF as evidence for an audit or an internal station release, then review it again after any change to the pack, test equipment or software.

What the main tests do

Insulation resistance and dielectric withstand confirm that the high voltage circuit is isolated from the chassis. Open-circuit voltage and cell spread detect wrong cell assembly or a weak cell. HVIL and contactor tests prove that the safety interlocks work. Leak tests of the enclosure and cooling circuit prevent water ingress and coolant leaks, which are serious in a high voltage product. Torque verification of busbars guards against high resistance joints that heat up in use.

Isolation tests protect against shock hazards
BMS checks confirm monitoring and protection are active
Leak tests protect against ingress and coolant loss

Records and control plan links

Every measured value should be stored against the pack serial number, not just a pass or fail. Link this checklist to the control plan and the PFMEA so each test traces to a failure mode. The same record supports containment if a cell lot is later found suspect, because you can list every pack that contains it. If your tests are automated, ensure that the data is written to the MES or quality system without manual retyping.

Common mistakes

A frequent weakness is that rework packs are retested only on the failed item. After any rework a full retest should run, because a repair can disturb other joints and sensors. Another is letting the station software or limits change without change control. A third is calibrating the test equipment but forgetting the fixtures, seals and probes, which also wear. Treat the station as a controlled process with its own FMEA.

Frequently Asked Questions

What test voltage is used for insulation resistance?

It depends on the pack voltage class and the customer specification. Do not assume a figure from a generic checklist. Take the test voltage, minimum resistance and dwell time from the customer requirement or the applicable standard, and record them in the control plan.

Is a leak test mandatory for every pack?

Many customers require leak testing of the enclosure and cooling circuit on every unit, but the method and pressure vary. Check your customer specification. Where it is sampled rather than 100 percent, the control plan should state the reason and frequency.

Why must rework packs get a full retest?

Rework can disturb connectors, sensors, seals or fasteners that passed earlier. A full retest confirms that the repair did not create a new fault and keeps the traceability record complete for the pack.

Does this replace the customer test specification?

No. It is a general checklist to prompt discussion and review. The customer specification, applicable standards such as ISO 6469 for electrical safety, and your PFMEA define the actual tests, limits and sample plans.

If your EOL data needs to reach quality, warranty and ERP records for traceability, Netray can discuss a private on-prem assistant that answers questions from that data.

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