Incoming Inspection of Lithium Battery Modules: A Practical Routine

Short answer: Incoming inspection of lithium battery modules covers packaging integrity, shipping documentation, visual checks for swelling, deformation and connector damage, open-circuit voltage measurement across the delivery lot, and confirmation that storage conditions (temperature, humidity and state of charge) are within specification before the modules enter stock.

A module that arrives at your facility undamaged is not automatically ready for stock. The condition of the cells inside is determined partly by what happened during transit and partly by how the modules are stored from receipt until assembly. The routine below gives a warehouse and assembly team a repeatable process that protects cell life and creates an evidence trail for any claim against the supplier.

For the rules governing the transport of lithium modules before they reach your dock, see the article on shipping lithium battery modules, which covers UN 38.3 and ADR with reference to UNECE.

Step 1: Packaging and transport damage

Before the pallet is broken down, inspect the outer packaging in the presence of the driver or before signing the delivery note.

Check for crush damage, puncture, forklift strikes or evidence that the consignment has been dropped.
Confirm that any tilt or shock indicators supplied by the shipper have not been triggered.
Note any discrepancy between the number of cartons or pallets on the delivery note and what has actually arrived.
Photograph any damage before moving the goods.

If outer damage is visible, mark the delivery note as received under reservation. Do not destroy packaging material until the inner inspection is complete: it may be needed for a freight claim.

Step 2: Documentation check

The paperwork that accompanies a shipment of lithium modules depends on the supplier, the project and the applicable regulations. At minimum, confirm that:

The packing list matches the physical count of modules and lot or batch numbers.
Any transport classification documents (such as a UN 38.3 summary or a material safety data sheet) are present and legible.
Lot or batch identifiers on the physical labels correspond to those on the accompanying documents.

Do not assume that a specific test report or cell-level data sheet will be included; what documentation travels with a given delivery is established per project with the supplier. If documentation is missing or inconsistent, record the discrepancy and contact the supplier before the goods enter stock.

Step 3: Visual inspection of each module

Inspect every module individually under adequate lighting. Use a flat, clean surface. The checklist below covers the most common fault indicators.

Inspection point	How to assess	Action on deviation
Case swelling or bulging	Sight along all six faces; use a straight-edge on the large faces	Quarantine immediately; do not charge or connect
Mechanical deformation or dents	Visual and tactile; compare to a reference module	Quarantine; photograph; report to supplier with batch data
Discolouration or heat marks	Visual inspection of case and terminals	Quarantine; note location and extent
Electrolyte leakage or residue	Check seams, vent areas and terminal bases; smell for solvent odour	Quarantine; treat as hazardous material; ventilate area
Connector and signal connector damage	Check housing, pins and locking tabs; mate and unmate once to confirm retention	Tag as non-conforming; do not integrate into a harness until assessed
Busbar contact surfaces	Inspect for corrosion, scratches deeper than the plating, or contamination	Clean with dry lint-free cloth if surface contamination only; escalate if base material is exposed
Label legibility	Confirm that the serial or lot number is readable and matches paperwork	Flag for re-labelling or supplier query before entering stock

Any module that fails a visual check must be physically separated from the conforming stock, marked clearly as non-conforming, and reported to the supplier with the batch number, the nature of the defect and supporting photographs. Do not attempt to repair, charge or discharge a visually suspect module.

Step 4: Open-circuit voltage measurement

Measure the open-circuit voltage (OCV) of every module using a calibrated digital multimeter. Record the value against the serial or batch number.

Two comparisons matter:

Against the datasheet. The supplier's documentation states the state of charge at which the module ships, and the datasheet gives the voltage window. A module that reads far above or below what that implies may have experienced a charging fault, a deep discharge, or self-discharge during extended storage in transit. Keep in mind that the voltage curve of LFP is flat over most of the state-of-charge range, so a voltage reading is a coarse indicator of charge level.
Against the spread within the delivery lot. Modules from the same production lot should show closely grouped OCV values. An outlier, a module whose OCV deviates clearly from the rest of the lot, warrants further investigation before integration. How much spread is acceptable depends on the product and on the state of charge, so ask the supplier for the acceptable OCV spread rather than assuming a number.

Document all readings. If a module's OCV is below the minimum discharge voltage specified in the datasheet, it must be quarantined and reported to the supplier: a deeply discharged lithium module should not be charged without guidance from the supplier.

Step 5: Storage conditions until assembly

State of charge

Store modules at the state of charge the datasheet recommends, which for lithium-ion chemistries is generally a low to moderate level rather than fully charged. In general terms the mechanism is this: at high SoC, the cathode is in a more oxidised and mechanically stressed state, and the solid-electrolyte interphase on the anode grows more rapidly, consuming lithium inventory. Combined with elevated temperature, storage at high SoC measurably accelerates calendar ageing. The rate of capacity loss under given conditions varies by chemistry, cell design and temperature; the datasheet of the specific product is the authoritative reference for the storage SoC recommendation.

For prismatic LFP and NMC cells and assembled battery modules, the recommended storage SoC is stated per product. If the modules arrive at a higher SoC than the storage recommendation, ask the supplier how to bring them to the target range. Do not discharge modules without the appropriate equipment and BMS connection.

Temperature and humidity

Store modules in a dry, temperature-controlled environment. Commonly published guidance for lithium prismatic modules (supported by IEC 62619, available at IEC) indicates:

Storage temperature: 0 °C to 35 °C for periods up to several months; lower temperatures slow calendar ageing but must remain above the minimum specified in the datasheet.
Relative humidity: below 65 % RH, non-condensing. Condensation on terminals and connectors promotes corrosion and can cause leakage currents across signal connectors.
Avoid direct sunlight and proximity to heat sources.

If modules are to be stored for more than three months, check the datasheet for any requirement to perform a periodic capacity top-up to prevent the SoC from drifting below the minimum storage voltage.

Fire separation and safety

Lithium modules must be stored in a dedicated area that complies with local fire regulations and any applicable insurance requirements. Minimum practical measures:

Separate lithium module storage from other flammable materials.
Maintain clear access for fire-fighting equipment.
Do not stack modules in configurations not specified by the supplier or that risk mechanical damage to the lowest layer.
Post relevant material safety data sheets at the storage area entrance.
Ensure staff handling the modules have received appropriate safety training.

For complete module systems intended for stationary applications, fire separation requirements may be governed by local building codes, insurer requirements and fire regulations. The overview of stationary battery standards explains which standards address system-level fire behaviour.

Handling non-conforming modules

A non-conforming module is any unit that fails a check in steps 1–4. The process is straightforward:

Remove the module from the conforming stock area immediately.
Mark it clearly and unambiguously as non-conforming; a physical tag is preferable to a label that can be overlooked.
Store it separately, maintaining the same temperature and humidity conditions as conforming stock, unless the supplier instructs otherwise.
Compile a report: batch number, serial number if available, date of receipt, nature of the deviation, photographs, and the OCV reading.
Contact the supplier with this package. Do not make assumptions about root cause; present the observations and allow the supplier to respond.

Keep the module isolated until the supplier has issued a disposition instruction. Do not return, re-use or dispose of a suspect module without written guidance.

Work with your supplier from receipt

The incoming inspection routine is the first stage of quality assurance for any pack build. Its value depends on consistency: every delivery, every module, documented in the same way. Deviations that are caught at goods-in rather than during assembly or in the field are generally easier to resolve. Where lot-level documentation is part of the delivery, it makes traceability straightforward; a well-kept goods-in log completes that chain on your side.

Get in touch

If you have questions about incoming inspection requirements for a specific module or need to discuss storage recommendations for a planned build, discuss your pack requirements with the Avantis Energy team.

Frequently asked questions

What should I check first when receiving lithium battery modules?
Inspect the outer packaging for crush damage, puncture or shock-indicator activation before breaking down the pallet, and verify that the packing list matches the physical count and batch numbers. Photograph any visible damage before moving the goods, and note reservations on the delivery documentation.

At what state of charge should lithium battery modules be stored?
Store modules at the state of charge the datasheet recommends, which is generally a low to moderate level rather than fully charged for LFP and other lithium-ion chemistries. Storage at high SoC accelerates calendar ageing because the cathode remains in a mechanically stressed, oxidised state and the solid-electrolyte interphase grows more rapidly. The exact storage SoC recommendation is stated in the datasheet of the specific product.

What temperature and humidity conditions are required for lithium module storage?
A dry, temperature-controlled space within the datasheet's storage range, with non-condensing humidity. Condensation on terminals promotes corrosion, and temperatures outside the specified range accelerate ageing. The product datasheet is the authoritative source for each module.

What do I do if a module arrives with visible swelling or deformation?
Quarantine the module immediately, separate it from conforming stock, and do not attempt to charge, discharge or connect it. Photograph the defect, record the batch and serial number, and report to the supplier with full details. Await a disposition instruction before taking any further action.

How do I identify an OCV outlier within a delivery lot?
Measure the open-circuit voltage of every module and record readings against batch or serial numbers. A module whose OCV deviates clearly from the rest of the lot warrants further investigation; ask the supplier what spread is acceptable for the product. Also compare each reading against the voltage the shipping state of charge implies; a reading outside that range requires supplier notification before the module enters stock.