The short answer
UN 38.3 tests the cell, not the box. Nothing in the packaging rule asks a package to pass it, and the package answers to a separate standard.
Cushioning is not a general rule here. It appears only in the exceptions, while the rule asks for a non-metal inner pack that fully encloses the cell.
Ask a supplier whether their lithium cells are UN certified and you will get a yes. Ask which thing carries the certificate and the answer gets vague.
Two separate approvals stand behind a shipped battery. One belongs to the cell or battery design, and the other belongs to the package it travels in.
The rule treats them as different things, and it never asks a package to pass the battery test. That single point settles most of the confusion, and it changes what a supplier’s yes is actually worth.
The second surprise is what the rule asks of the box. Cushioning does not appear in the general rules at all, and the demands that do appear are about enclosure and conductive metal.
This reference covers the two approvals, what the package has to do, the thresholds that decide which rules apply, the state of charge figure, and the mark with its deadline.
Two Approvals, and They Are Not the Same
The packaging section opens with the battery test. Each lithium cell or battery must be of a type proven to meet the criteria in sub-section 38.3 of the UN Manual of Tests and Criteria.
Read what that sentence attaches to. The type is the cell or the battery, so the approval travels with a design rather than with a shipment.
One clause closes an obvious loophole. The tests apply whether or not the cells used to build a battery were themselves of a tested type, so assembling tested cells does not inherit their approval.
The maker keeps the paperwork, not the shipper. A record of the test has to survive for as long as the design ships, plus one year after that.
And the package gets no mention in any of it. Nothing asks a box to pass the battery test, which is why UN certified packaging means something else entirely.
One approval belongs to the design, the other to the box, and a yes about either says nothing about the other.
What the Rule Asks of the Package
Open the packaging paragraph expecting foam and you will not find it. The demands are about enclosure and metal instead.
Cells and batteries go into non-metal inner packs that completely enclose them. Those inner packs also have to keep the cell apart from equipment, other devices and any conductive material.
Short circuits get named twice. Each battery needs a means of preventing external short circuits, and the packaging has to prevent them as well.
Movement gets its own clause. The packaging must prevent damage from shifting or from how the cells sit inside, and a device travelling with cells needs securing too.
Which is where the absence matters. Cushioning shows up only in the exceptions for prototypes, low production runs and damaged or defective batteries, so for an ordinary shipment the rule asks for separation rather than padding.
That is a different brief from the one a cushion answers, and the gap is worth naming on a drawing. A drop test height sets how hard a package lands, while this rule cares what touches what inside it.
The Thresholds Decide Everything Else
Almost every branch in these rules turns on size. Watt-hours for lithium ion, grams of lithium for lithium metal, and mass limits on the finished package.
| Limit | Figure | Applies to |
|---|---|---|
| Lithium ion cell | 20 Wh | Smaller-cell route |
| Lithium ion battery | 100 Wh | Smaller-battery route |
| Lithium metal cell / battery | 1 g / 2 g | Lithium content |
| Highway or rail only | 60 Wh cell, 300 Wh battery; 5 g / 25 g | Surface modes |
| Package gross weight | 30 kg | Not with equipment |
| Air, with equipment | 5 kg net | Plus spares |
| Air, without equipment | 2.5 kg metal / 10 kg ion | No UN pack |
| Drop test | 1.2 m | Cells alone |
The surface-only row is the one buyers miss. Higher watt-hour and gram limits exist, but a package using them carries wording that forbids it from aircraft and vessels.
The drop figure will look familiar from transit testing, and ISTA 3A exercises altitude and low pressure the same way the battery test series does.
The 30 Percent Is Three Different Rules
Every guide quotes a 30 percent state of charge for air shipments. The figure is right and its force is not uniform.
The agency guide sorts it by packing instruction. Under two sections of one instruction and the first section of another, cells and batteries must ship at no more than 30 percent of rated capacity.
One instruction splits on a small figure. Above 2.7 Wh the limit is mandatory, while at or below 2.7 Wh the guide says cells should go out at or below 30 percent, which is advice.
Batteries inside equipment get softer wording again. There the 30 percent appears as a recommendation, with an indicated battery capacity of no more than 25 percent offered as an alternative.
So one number carries three different weights, and which one applies depends on how the battery travels rather than on what it is.
The limit also does not live in the packaging section. That section points at a special provision elsewhere, and excepts medical device cells packed individually, in a rigid outer packaging, with short-circuit protection.
The Mark, and a Deadline Already Close
The lithium battery mark carries a UN number, and the number says what is in the box. UN3090 and UN3480 cover cells or batteries alone, while UN3091 and UN3481 cover them packed with or inside equipment.
The rule specifies its geometry rather than suggesting it. The mark is a rectangle or square with hatched edging, not less than 100 mm wide by 100 mm high, with hatching at least 5 mm wide. Symbols sit in black on a contrasting background, and the hatching runs red.
And there is a date. Shippers may use the previous version of the mark until 31 December 2026, so artwork still carrying it has a short run left.
Aircraft wording sits alongside the mark. Some cases call for FORBIDDEN FOR TRANSPORT ABOARD PASSENGER AIRCRAFT markings or a CARGO AIRCRAFT ONLY label, and prototype or low-production packages are not permitted on passenger-carrying aircraft at all.
So the useful order of work runs backwards from the usual one. Settle the chemistry and size first, because they pick the packing instruction, and the instruction picks the mark and the wording.
Then specify the inside before the outside. A non-metal inner pack that fully encloses each cell does more here than any thickness of foam, and ESD packaging is the nearest habit a buyer already has.
And check the artwork date before reprinting anything. A mark that was correct last year may not be correct next January, which makes the plate change a scheduling question rather than a design one.
Common Questions
Does UN 38.3 certify the package?
No. It applies to the cell or battery type, and nothing in the packaging section asks a package to pass it. The package answers to the performance standards in part 178 and to the packaging rules in the section itself.
Does the rule require cushioning around lithium cells?
Not in the general requirements. Cushioning appears only in the exceptions for prototypes, low production runs and damaged or defective batteries. What the general rules ask for is a non-metal inner pack that completely encloses the cell.
Is the 30 percent state of charge mandatory?
It depends on the packing instruction. Some make it mandatory. One makes it mandatory above 2.7 Wh and advisory at or below, and for batteries inside equipment it is a recommendation with a 25 percent alternative.
How big does the lithium battery mark have to be?
Not less than 100 mm wide by 100 mm high, with hatched edging at least 5 mm wide, in red with black symbols on a contrasting background. A 100 mm by 70 mm mark is allowed where the package is too small.
How to weigh this page. The requirements and figures come from the current text of the federal packaging section, read directly, and the packing instruction wording from the aviation agency’s own 2026 guide.
This is guidance for writing a specification, not safety advice about batteries, and it does not replace the regulations. That guide says so itself, and adds that carrier rules can be stricter. Four things stay out on purpose. The rule incorporates the UN test series by reference rather than reprinting it. Nobody read the special provision carrying the state-of-charge limit, or the paid international manual. The mark artwork appears only as an image, so the dimensions are here and the drawing is not. A fuller agency handbook covers the rest.
Key takeaways
- UN 38.3 approves a cell or battery design, and nothing in the packaging section asks a package to pass it.
- Assembling cells of a tested type does not inherit their approval, and the maker keeps the record for as long as the design ships plus a year.
- Cushioning appears in no general packaging rule, only in the prototype, low-production and damaged-battery exceptions.
- The 30 percent state of charge is mandatory, advisory or recommended by packing instruction, and it sits outside the packaging section.
- The mark runs not less than 100 mm by 100 mm, and the previous version is good only until 31 December 2026.