An inspection report arrives with a sample size, an accept number, a reject number and a conclusion. If the accept and reject columns look like a lottery table, this is the guide that turns them into a decision: ship, hold, sort or reject.
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This guide is part of our Charger Quality & Inspection. Read the full topic guide for the decisions that come before and after this step.
What AQL actually controls
Acceptable Quality Limit is a sampling method, not a promise of perfection. It defines how many defective units in a random sample are tolerated before the whole lot is rejected, at a chosen inspection level and defect class. The purpose is to make an accept-or-reject decision on a shipment from a sample, with a known risk of accepting a bad lot or rejecting a good one. It does not measure the quality of every unit, and it does not replace process control.
Sampling level and lot size: reading the first block
The report should state the lot size, the inspection level and the resulting sample size. The standard general inspection levels trade cost against confidence: a normal level is the default, a tightened level is used when a supplier’s quality has slipped, and a reduced level is used when performance has been stable. If the report does not state the level, the sample size cannot be interpreted, and the conclusion is not auditable.
Critical, major and minor defects for chargers
| Class | Charger examples | Typical treatment |
|---|---|---|
| Critical | Safety hazard, exposed conductor, insulation failure, incorrect mains rating | Zero tolerance; lot rejected |
| Major | No output, wrong output, intermittent charging, overheating, port failure | Strict AQL; commonly zero accept |
| Minor | Cosmetic blemish, print imperfection, accessory issue | Applied AQL with defined limits |
The defect classification matters more than the sampling numbers. A report that applies a loose AQL to a functional failure is mis-classified, and the conclusion cannot be trusted even if the arithmetic is correct.
The accept and reject numbers
For a given sample size and AQL, the standard gives an accept number and a reject number. If the number of defects found is at or below the accept number, the lot is accepted; at or above the reject number, it is rejected. Where the accept number is zero, a single defect fails the lot. Read the numbers against the class: a lot can pass on minors and fail on majors in the same report.
What full inspection adds beyond sampling
Sampling estimates; full inspection decides. For critical parameters – dielectric strength, output voltage under load, safety-related dimensions – the appropriate control is 100% test rather than sampling. This is why a charger programme typically runs electrical and aging tests on every unit and applies AQL sampling to appearance and packing. A report that samples a safety parameter is a weak control.
When a batch fails: the four possible actions
- Reject and rework: the defect is reworkable within the approved boundary
- Reject and sort: 100% inspection, good units ship, defective units are scrapped
- Reject and replace: production of a new lot against the same specification
- Accept under concession: only with a written deviation approved by the customer
The concession route is legitimate for a minor cosmetic deviation with a defined limit, and it should never be used for a functional or safety defect.
Recording and retention of inspection data
Inspection records should be linked to the batch and date code, retained for the period stated in the quality agreement, and available for audit. For a claim made months after shipment, the inspection record is what shows whether the failure was representative or isolated. Retaining only the pass or fail conclusion is not enough; the defect categories and counts are what allow a later investigation.
What to compare across repeated shipments
Look at the trend, not the single result: the minor defect rate across the last three shipments, the defect categories that repeat, and whether corrective actions have reduced them. A stable rate at a low level is normal variation; a rising minor rate often precedes a major failure. This is where the batch report becomes a supplier management tool rather than a shipping document.
Batch-report audit checklist
- Lot size, inspection level and sample size stated
- Defect classes defined and applied correctly
- Accept and reject numbers consistent with the sampling plan
- Functional and safety parameters tested 100%
- Defect categories and counts recorded, not only the verdict
- Record linked to the batch or date code and retained
Evidence gate: separate 100% tests from sampled inspection
A batch report is useful only when it states what was tested on every unit, what was sampled and which acceptance rule controlled the decision. The three records must point to the same model and production lot.
Use the following record with the article’s technical guidance and confirm the applicable requirements against the linked authoritative source.
| Approval checklist | Evidence to request | Pass condition | Stop condition |
|---|---|---|---|
| Test method | Approved procedure and equipment list | Method, limits and instrument are identified | The report says only pass or fail |
| Coverage | Unit-level log or sampling plan | 100% and sampled checks are clearly separated | A sample result is presented as a unit-level test |
| Traceability | Lot, date, line and model identifiers | The report traces to the shipment | The tested lot cannot be linked to the order |
| Failure action | Nonconformance and corrective-action record | Failures have disposition and retest evidence | Failed units disappear from the summary |
Stop/go conditions
- Do not accept a report that omits the test limit, sample size or lot identity.
- Stop release when failed units lack a documented disposition, corrective action and retest result.
FAQ
What AQL level is normal for consumer chargers?
It varies by customer, but the practical rule is stricter for functional defects and looser for cosmetics, with critical defects at zero tolerance. The level should be written into the quality agreement rather than assumed.
What happens if a batch fails AQL inspection?
The lot is held and a disposition decision is made: rework, 100% sort, replacement or a customer-approved concession. The choice depends on whether the defect is functional, cosmetic or related to safety.
How long should inspection records be kept?
Long enough to cover the warranty period and any reasonable claim investigation. Records linked to the date code are what make a late claim diagnosable.
Next step
Wecent Group applies documented inspection gates with electrical and aging tests on every unit and retained batch records. Send your quality agreement requirements to the contact page. Related reading: inspection gates, batch traceability, quality control and rework and re-inspection. External references: ISO 2859-1 sampling procedures, ISO 9001, AIAG, GS1 standards, IEC standards and UL.
More on this topic: wireless charging pads and wireless charger manufacturing.