The short version: with transport status unsettled, the sample never arrives and the slot you booked is empty
On powered wheelchair projects the step that stalls the schedule most often is not the testing itself, it is getting the battery sample out of the door. Factories usually work in the order of booking the slot first and shipping the sample afterwards. Then the freight forwarder asks for transport classification documentation, nobody can produce it, the sample is held at origin, the laboratory bench sits empty and everything downstream slides.
The correct order is the reverse. Confirm the battery's transport status and packaging plan first, then set the shipping date, and only then fix the test slot. These three items usually sit with three different departments, purchasing, logistics and quality, and each assumes one of the others owns it. That is the source of the disconnect.
One sentence to work from: transport status for a battery is a logistics question, battery safety performance is a testing question, and the documents for the two cannot substitute for each other.
What each of the three chains actually solves
| Chain | What it solves | Common misreading | What the disconnect looks like |
|---|---|---|---|
| Battery and charger requirements at chair level | Safety and performance of the battery and charger as fitted to this wheelchair | Assuming a cell report is enough | Supplementary testing demanded at combination level |
| Safety requirements for cells and battery packs | Intrinsic safety characteristics of the cell and of the pack | Assuming a pack report covers the cells | Document level does not match, submission returned |
| Transport classification and dangerous-goods declaration | Whether the battery can go by air, sea or courier | Assuming a test report works as a transport document | Sample refused or detained |
The row most often overlooked is the last one. A test report states whether the product meets the corresponding technical requirements; a transport document answers whether a carrier is willing to accept it. The two may be performed on the same battery, yet the documents are not interchangeable, and that has to be said out loud at the project kick-off.
Cell level and pack level do not substitute for each other
This is the technical point behind most returned submissions. IEC 62133-2 addresses safety requirements for portable sealed secondary lithium cells and batteries, and the cover page of the report states whether the coverage object is the cell or the pack. The chair side, by contrast, is concerned with how the battery and charger behave on this vehicle, which is what the ISO 7176-25 part addresses. Different objects under test, different test purpose, different form of conclusion.
In practice, use this comparison to judge whether the documents in hand are sufficient:
| Document you hold | Question it can answer | Question it cannot answer |
|---|---|---|
| Cell-level safety report | Intrinsic safety characteristics of the cell | Protection logic after assembly into a pack, behaviour at the chair interface |
| Pack-level safety report | Protection strategy and construction of the pack | Charge and discharge behaviour once fitted to this wheelchair |
| Battery and charger items at chair level | Actual behaviour of the combination on the wheelchair | Intrinsic safety characteristics of the cell |
| Transport classification document | Whether it can be carried under dangerous-goods conditions | Whether the product meets the technical requirements of the sales market |
The method is crude but it works. Pick up a document and read what it names as its coverage object. If it says cell, do not use it to answer a pack question. That sounds obvious, yet the rate at which the wrong document is submitted is not low, usually because purchasing forwards the supplier's cell paperwork straight to the project team and the project team assumes it covers the whole pack.
Change the cell or the pack construction and both chains have to be revisited
Changing cell suppliers is normally a cost decision, and the decision chain often does not pass through quality. But one change of material affects three documents at once: the cell-level safety report no longer covers the product, the object of the transport classification has changed, and the battery and charger items at chair level need reassessment.
| Change | Cell-level safety document | Transport classification document | Chair-level items |
|---|---|---|---|
| Different cell brand or model | Reissue | Reissue | Reassess |
| Same cell, different pack construction | Usually can be carried over | Reassess | Reassess |
| Protection board design change | Depends on what changed | Reassess | Reassess |
| Battery housing or mounting change | Usually can be carried over | Reassess | Depends on the mounting interface |
| Different charger | Not involved | Not involved | Reassess |
| Labels and rating plate only | Not involved | Document update | Document update |
The difference in cost is easy to see. Catch the impact of a material change at the prototype stage and all you owe is a document update and one targeted verification. Catch it just before a bulk shipment and you have goods sitting in the warehouse waiting on paperwork, or coming back from the destination port, with freight, storage and a missed delivery date charged together.
Shipping the sample: who owns packaging and declaration
Default position: the shipper is responsible for transport compliance, the laboratory is responsible for receiving and testing. A laboratory cannot make the dangerous-goods declaration on the client's behalf, and it cannot decide on the carrier's behalf whether the packaging is acceptable. Saying this at kick-off avoids a lot of mutual waiting later.
Four things to confirm before shipping:
- prepare the battery's state of charge according to the carrier's requirements, taking the forwarder's written confirmation as the governing statement;
- apply outer packaging, inner cushioning and markings per dangerous-goods transport requirements, rather than simply putting the pack in a plain carton;
- assemble the accompanying documents in full, including the transport classification document and the safety data sheet;
- state the battery type and the number of pieces in the consignee information so the laboratory can arrange storage conditions in advance.
Miss any one of these and the outcome is the same: the sample stops somewhere in transit. The cost of stopping is not only freight, it is that the window the laboratory reserved for you is burned and you go back into the queue.
How to sequence the schedule so nothing idles
Work in this order and you will rarely see the slot arrive without the sample:
- Freeze the submitted configuration. Cell model, pack construction, protection board design and charger model are fixed once, with no further changes.
- Check the document levels. Use the comparison above to see which level your existing documents cover and which level is missing.
- Close the transport classification gap. The lead time here is usually shorter than whole-product testing, but putting it last makes it the bottleneck.
- Confirm packaging and carrier, with written confirmation of acceptance issued by the forwarder.
- Only then book the laboratory slot, and ship within the agreed delivery window.
In that sequence the first two steps are paperwork and cost essentially nothing; move them to the end and you have hardware in transit while a slot idles. For the scope of chair-level and battery-related items, start with electric wheelchair testing; the battery chain for scooters follows the same logic, see mobility scooter testing.
Pre-shipment self-check table
| Check item | Owner | What it looks like when skipped |
|---|---|---|
| Is the submitted configuration frozen | R&D and purchasing | Material changed mid-test, report does not cover the model on sale |
| Has the coverage object of each document been checked | Quality | Cell paperwork used to answer a pack question, submission returned |
| Is the transport classification documentation complete | Quality and logistics | Forwarder refuses, sample cannot ship |
| Are packaging and marking compliant | Logistics | Detained in transit, slot idles |
| Is the state of charge prepared as required | Production | Carrier refuses, or the unit cannot be tested directly on arrival |
| Are the accompanying documents complete | Project team | Laboratory cannot confirm the object under test, repeated document chasing |
| Does the consignee information identify the battery | Logistics | Storage conditions do not match at goods-in |
The underrated row in that table is the first one. Change the cell halfway through testing and most of the completed work is void, and when cost pressure is high this happens somewhere almost every year.
A note on accreditation scope
Battery-related projects span several parts, so the scope question deserves even more attention before an order is placed. To state it plainly: an accreditation mark only demonstrates that the laboratory holds the corresponding technical competence within its accredited scope; it does not constitute a commitment regarding market access outcomes in the target market. Whether you can enter the target market also depends on the requirements of the local competent authority, how the product is classified and the completeness of the technical documentation.
It is also worth confirming at the concept stage whether ISO 7176-31 and other parts of the series apply to your product; execute according to the corresponding part, with the current valid version of the standard text governing. For the overall breakdown of projects, start with testing services, and for how comparable projects were handled, see testing cases.
If you want the sequence sorted out
Problems on the battery chain are seldom technically hard. Almost all of them are sequencing problems, with logistics compliance left until last. SUNGO Mobility Testing Lab is the dedicated wheelchair and mobility aid testing lab within our group, accredited by CNAS, CMA and IAS (USA), with laboratories in Shanghai and Hefei. Send us your cell and pack design and we can list the document gaps across the three chains first, then work backwards from there to the shipping date and the slot, so the sample is not stuck in transit while the bench sits empty. Call +86 132 4819 8029, or request a quote with the cell model, the pack construction and the charger details.