A power bank pre-shipment inspection compares a finished production lot with the purchase order, approved specification, golden sample and packaging requirements. Before it starts, the buyer needs to define the lot and sampling plan, defect classes, acceptance numbers, test methods and release authority. The report should lead to a clear decision: release, hold, rework or reinspect.
PSI provides evidence about the finished lot that is ready to leave the factory. Sampling cannot prove that every unit is defect-free, and the inspection does not replace product validation, safety certification or lithium-battery transport controls. It answers a narrower question: does this lot meet the buyer’s agreed acceptance rules?
What is a power bank pre-shipment inspection?
A pre-shipment inspection, often shortened to PSI, is an inspection of finished goods before the buyer authorizes shipment. An inspector checks the available quantity, selects samples from the lot, examines workmanship and packaging, performs the agreed functional tests, records defects and reports the findings.
The inspector may work for the buyer, the factory or an independent inspection company. Independence can reduce conflicts, but a clear written scope matters more than the company name on the report. No inspector can make a reliable decision from an instruction as vague as “check the quality.”
Keep validation, sample approval and shipment inspection separate
Several quality activities occur during an OEM project. They answer different questions and should not be treated as substitutes for one another.
| Activity | Main question | Typical timing |
|---|---|---|
| Product validation | Does the design meet its performance, safety and reliability requirements? | During development and before mass production |
| Pre-production sample approval | Is this physical sample and its documented configuration approved as the production reference? | Before materials and mass production are released |
| Pre-shipment inspection | Does the finished production lot conform to the approved requirements under the agreed sampling plan? | After production and at the agreed packing-readiness point |
| Transport document review | Are the battery design, test summary, marks, packaging and shipping arrangements suitable for the planned route? | Before the shipment is accepted by the logistics chain |
Approve a controlled reference before production. The power bank sample approval checklist explains how to record the model, cell, PCBA, firmware, artwork and packaging revision. Without that baseline, an inspector may find differences but cannot tell which version the buyer approved.
Prepare the inspection file before booking an inspector
Send the inspection company the same controlled documents used by the factory. The inspection file should contain:
- Purchase order, model number, quantities and destination markets
- Approved product specification with revision date
- Golden sample, signed sample record or detailed reference photographs
- Approved bill of materials or a list of controlled components
- Logo, rating label, barcode, manual and packaging artwork
- Carton specification, packing method and accessory list
- Required compliance and transport documents
- Sampling standard, inspection level and AQL values
- Buyer-approved definitions of critical, major and minor defects
- Test methods, equipment, conditions and acceptance limits
- Open corrective actions from sample approval or earlier production
Where a requirement is difficult to describe, use a drawing or photograph with an acceptable limit. “No scratches” is open to argument. A defined viewing distance, lighting condition and maximum mark size gives both sides a usable rule.
Choose the inspection timing and readiness point
Set the readiness point in the purchase order or inspection brief. The goods should be far enough through production and packing for the selected samples to represent the shipment. At the same time, cartons and pallets must remain accessible for random selection.
There is no universal percentage of packed goods that suits every order. A common readiness rule used by one inspection provider may be unsuitable for a mixed-SKU shipment or a project that needs carton-level checks. Ask the factory to report completed quantity, packed quantity, unfinished quantity and any goods stored in another area before the inspector arrives.
Define the inspection lot before selecting samples
The lot is the population from which samples are taken and to which the inspection decision applies. Record the SKU, model, colour, capacity, hardware revision, firmware revision, production dates, battery-cell lot, carton range and total quantity.
Do not silently combine goods that differ in a material way. Two capacities in the same enclosure, different cell suppliers, separate production runs or different destination labels may need separate lots or a stratified sampling instruction. If the shipment is split among several warehouses, record every location and decide how samples will be allocated.
Select samples randomly across the shipment
The inspector, not the factory, should select the units. Samples should come from different cartons, pallet positions and accessible storage areas. Factory-prepared samples can hide variation between assembly lines, shifts or cell lots.
Record each selected carton’s number and each sample’s identification. Keep samples for destructive, long-duration or laboratory tests separate from the routine appearance and function sample. If a failed unit is replaced by an unrecorded spare, the defect count and report lose meaning.
How AQL sampling works
ISO 2859-1:2026 provides sampling schemes indexed by acceptance quality limit, or AQL, for lot-by-lot inspection by attributes. In a single-sampling plan, the lot size and selected inspection level lead to a sample-size code and sample size. The chosen AQL then gives an acceptance number and rejection number.
The current ISO edition includes normal, tightened, reduced and skip-lot procedures with switching rules. A buyer should not copy one sample size from an online chart and use it for every order. The plan, inspection state and switching rules need to be selected and documented.
AQL is not a promise that the shipment contains no more than a stated percentage of defective units. ASQ defines acceptance sampling as inspecting a sample from a lot to decide whether to accept that lot. Sampling controls decision risk; it does not reveal the exact defect rate in the full shipment.
Use a licensed copy of the current standard or an inspection provider’s controlled procedure to obtain the tables. The buyer should approve the inspection level, AQL values, defect classes and acceptance rules before production ends.
Do not use one universal AQL for every power bank order
The appropriate plan depends on the buyer’s risk, order history, product maturity, destination, sales channel and cost of failure. A promotional order, a retail launch and a power bank bundled with another device may justify different inspection rules.
Critical defects often need stricter treatment than cosmetic defects, and a buyer may contractually require zero acceptance for a defined critical condition. That rule must be written into the inspection brief. It should not be inferred from a generic checklist after a defect is found.
Classify critical, major and minor defects in writing
Defect classification determines how findings are counted, so examples should be agreed before inspection. The following table is a starting point, not a universal legal definition.
| Defect class | Practical meaning | Possible power bank examples |
|---|---|---|
| Critical | A condition that may create a safety, legal or serious transport risk, or violates a buyer-defined zero-tolerance requirement | Swollen battery, abnormal overheating, exposed conductor, evidence of leakage, serious battery identity mismatch or prohibited marking condition |
| Major | A failure likely to make the product unusable, materially different from the approved specification or unacceptable to the intended customer | Wrong model or capacity label, non-working output, required fast-charge profile absent, built-in cable failure, missing accessory, incorrect retail barcode or large assembly gap |
| Minor | A workmanship or cosmetic deviation that does not materially affect normal function | Small surface mark outside the agreed appearance limit, slight print-position shift or minor colour variation within a usable product |
The same observation may change class according to location, severity and intended market. A scratch on a hidden surface is not equivalent to damage across the brand mark. The report should include photographs and measurements rather than only a defect label.
Use a fixed inspection sequence
A consistent sequence reduces missed checks and prevents units from being mixed after testing.
- Confirm the factory, purchase order, lot identity, quantities and readiness.
- Select cartons and units according to the approved sampling instruction.
- Check shipping cartons, retail packaging, artwork, labels, barcodes, accessories and manuals.
- Inspect appearance, assembly, dimensions, weight and workmanship.
- Test charging input, wired outputs, built-in cables, indicators, buttons and wireless functions that apply to the model.
- Perform agreed measurements on the defined subset and under recorded conditions.
- Review traceability, production records and required documents.
- Count defects by class, photograph findings and issue a report with raw results.
Use the detailed power bank quality testing guide to define electrical and capacity test methods. A PSI checklist should refer to those methods instead of reducing them to an unchecked box.
Check packaging, labels and shipment identity
Packaging errors can block customs clearance or produce costly relabelling even when the power bank works. Compare the retail box, rating label, manual, master carton and shipping marks with approved artwork. Scan barcodes rather than judging them by appearance.
- Correct model, capacity, watt-hours and input/output statements
- Brand, logo, colour and artwork revision
- Destination language and required importer information
- Barcode content, placement and scan result
- Accessories, cable type, manual and warranty material
- Units per carton, carton dimensions, gross weight and carton marks
- Protection against movement, abrasion and connector damage
Do not ask an inspector to approve regulatory artwork without giving the approved reference and destination requirements. The inspector can compare versions and report mismatches; legal responsibility remains with the parties placing the product on the market.
Check workmanship and basic function
Inspect enclosure fit, seams, ports, connectors, cables, buttons, display windows, printing and surface finish. Measure the agreed dimensions and weight with calibrated equipment. Functional checks should cover every interface listed in the specification, including whether a USB-C port is input, output or bidirectional.
For wired output, record the test load, voltage, current and charging profile. For multi-output models, verify the combinations stated in the port matrix. For a magnetic wireless model, record alignment, charging indication, device or test receiver, case condition and temperature observation. Do not convert an unverified marketing claim into an inspection pass criterion.
Use a smaller defined subset for measured performance tests
Some tests take longer than the inspection visit or consume a large share of the available sample. Usable energy, full recharge time, conversion efficiency and thermal behaviour require defined starting conditions, equipment and test profiles. State how many units will be tested and whether the work will be completed at the factory, an inspection company or a laboratory.
Nominal mAh describes the internal battery at its nominal voltage. It should not be compared directly with output mAh measured at another voltage. Record watt-hours, output voltage, load, cutoff point, ambient condition and cable setup so another person can reproduce the result.
Know which checks belong outside routine PSI
| Check | Typical control route | Reason |
|---|---|---|
| Carton count and shipment identity | Quantity or carton-level verification | The shipment must match the order and packing list |
| Appearance and basic function | AQL sample | These are attribute-based conformity checks on finished units |
| Usable energy or recharge time | Defined performance subset | The tests need time, conditions and measured data |
| Cycle life, abuse and full reliability programme | Development or laboratory validation | These tests cannot be established by a short shipment visit |
| Applicable product safety certification | Accredited laboratory and market-specific compliance process | A visual inspection is not a certification assessment |
| UN 38.3 test evidence and transport acceptance | Document review plus logistics-provider requirements | Transport rules apply to the battery design and planned shipment, not merely the sampled units |
IEC 62133-2:2017+A1:2021 specifies safety requirements and tests for portable sealed secondary lithium cells and batteries within its scope. The UN Manual of Tests and Criteria includes lithium-cell and battery provisions in subsection 38.3. These documents define work that cannot be recreated by a quick functional check during PSI.
Review traceability and battery transport documents
Match the finished model with the approved cell, battery configuration and relevant reports. Record cell maker, cell model, production lot, finished-product lot and firmware or hardware revision where applicable. A report for a different battery design should not be accepted because the brand name looks similar.
Le UN Manual of Tests and Criteria, Revision 8 and Amendment 1 contains the current published changes to subsection 38.3. Air shipments also need to follow the applicable carrier, route and dangerous-goods rules. The IATA 2026 Battery Guidance Document is based on the 2025-2026 ICAO Technical Instructions and the 67th edition of the IATA Dangerous Goods Regulations.
A PSI report should confirm that specified documents were available and consistent with the inspected model. It should not state that a shipment is legally cleared for every route. Final acceptance depends on the actual classification, state of charge where regulated, packaging, marks, declarations, carrier and route.
Require an evidence-based inspection report
A buyer who was not at the factory should still be able to see what was inspected and how the result was reached. At minimum, require:
- Supplier, factory address, inspection date and inspector
- Purchase order, SKU, model, lot size and packing readiness
- Sampling standard, inspection level, AQL values and sample size
- How cartons and units were selected
- Defect count by class with acceptance and rejection numbers
- Raw measurements, equipment details and test conditions
- Photographs of samples, packaging, labels and every defect
- Document names, report numbers and revisions reviewed
- Unfinished, inaccessible or untested items
- Overall result and the person authorized to release the shipment
Photographs should show both context and detail. A close-up of a damaged port without the sample ID cannot be traced. A meter display without the connected product and test settings is weak evidence.
Decide whether to release, hold, rework or reinspect
A “pass” result from the inspection company is one input to the shipment decision. The buyer still needs to review open issues, specification deviations and document status. A sampled lot can meet the numerical defect rule while containing a specification change the buyer has rejected.
If the lot fails, place it on hold. Ask the factory to contain the affected goods, identify the cause, define the rework scope and provide evidence. Reinspection should use an agreed plan after rework, not a few hand-picked replacement units. Record whether the original lot was fully screened, partially reworked or rebuilt.
Copy-ready power bank inspection brief
Complete this brief before booking the inspection. Replace every bracketed item with a controlled requirement.
Buyer and purchase order: Factory and inspection address: Product model and SKU: Hardware, firmware and artwork revision: Lot definition and quantity: Required packing-readiness point: Approved specification and golden sample: Sampling standard and edition: Inspection level and inspection state: AQL for critical, major and minor defects: Buyer-approved defect definitions: Sample allocation by SKU or production lot: Packaging and artwork checks: Functional tests and acceptance limits: Performance subset and test conditions: Traceability records to review: Compliance and transport documents to review: Required report photographs and raw data: Person authorized to release shipment: Action if the lot fails:
For a new project, send the same acceptance requirements with the power bank RFQ. This gives the manufacturer time to quote test work, plan production records and identify requirements that need laboratory support.
Questions buyers often ask
What is checked during a power bank pre-shipment inspection?
The scope normally includes shipment quantity, product identity, packaging, labels, workmanship, dimensions and agreed functional tests. Measured performance, document review and traceability can be added when the methods and sample sizes are defined in advance.
What does AQL mean in a factory inspection?
AQL is an index used in an acceptance sampling scheme. Together with the lot size, inspection level and inspection state, it helps determine the sample size and acceptance or rejection criteria. It is not a measurement of the exact defect percentage in the shipment.
Which AQL should a power bank buyer choose?
There is no single value for every buyer or model. Choose values and critical-defect rules according to product risk, destination, sales channel, project maturity and supplier history. Put the decision in the purchase specification before inspection.
Can an inspector verify the true capacity of a power bank?
An inspector can measure usable output energy on a defined subset if the equipment, starting charge, voltage profile, load, cutoff point and acceptance limit are specified. A short functional check cannot establish rated capacity, conversion efficiency and long-term cell performance by itself.
What happens if the inspection lot fails?
Hold the shipment, review the defects and require a written containment and corrective-action plan. After rework or screening, reinspect the lot under an agreed plan. Do not release it only because a few replacement samples pass.
Does PSI replace certification or UN 38.3 testing?
No. PSI checks conformity of a finished lot under a sampling plan. Product safety standards, destination-market compliance and lithium-battery transport testing require their own procedures and evidence. The inspector can review whether specified documents match the product, but cannot create laboratory compliance through visual inspection.
Official references used for this guide
- ISO 2859-1:2026, sampling schemes indexed by AQL for lot-by-lot inspection
- ASQ Quality Glossary, acceptance sampling and AQL definitions
- IEC 62133-2:2017+A1:2021, safety requirements for portable sealed secondary lithium cells and batteries
- UNECE, UN Manual of Tests and Criteria Revision 8 and Amendment 1
- IATA 2026 Battery Guidance Document
Plan the inspection while the order is still controllable
PSI planning starts before the inspector reaches the factory. Define the approved configuration, lot, sampling rules, defect classes and test methods while the factory can still prepare records and clarify requirements. If those decisions wait until the goods are packed, the report may only document a disagreement that could have been resolved earlier.
For a YULIDA order, send the model, quantity, destination market and required checks through the page de contact. The factory can prepare the corresponding model specification, production records, reference samples and packing information. The buyer or its appointed inspection company should approve the final sampling and release rules.
Sources officielles et vérification
Ces sources primaires étayent les informations de cet article sur les normes, la compatibilité, la sécurité ou le transport. Vérifiez les exigences actuelles pour le modèle précis et le marché de destination.
- Commission électrotechnique internationale — Normes électrotechniques internationales et leurs domaines d’application.
- International Air Transport Association — Lithium-battery transport requirements and industry guidance.
