What UN Number Does Your Robot Battery Pack Ship Under?

Your robot battery pack ships under UN 3481 when it is installed in the robot or packed in the same crate as the robot, and under UN 3480 when it travels in its own packaging with no equipment alongside it. The UN number describes the shipment, not the pack. The same 48-volt pack can leave your dock under one number on Monday and the other on Thursday without a single cell inside it changing.

I have stood in that decision more times than I want to admit, and it is almost never made at a desk. It gets made at 6:20 in the morning on a dock, under fluorescent light, with the crate lid leaning against a rack and the freight driver already tapping on his phone.

The crate, the bolts, and the spare

Picture the scene, because I promise you will live it.

The robot is bolted to its shipping base. Torque stripe intact. The pack is inside the machine, cable run, cover plate screwed down. That part is clean.

Now look in the corner of the crate. There is a foam cutout, and in it sits a second pack, wrapped in its own bag, because the customer asked for a spare and swapping a pack in the field is a two-hour job they did not want to schedule around a purchase order.

Look at the paperwork in your hand. If it says Lithium ion batteries, 9, UN 3480 for the whole shipment, someone wrote that last week when the spare was going to ship in its own carton and nobody told them it changed. If it says UN 3481 and lists the loose spare as part of the equipment, someone made a different mistake, and it is the one that gets shipments refused.

One pack, three shipments

The distinction has nothing to do with the battery. It is entirely about the relationship between the battery and everything else in the box.

UN 3480. Batteries shipped alone. Nothing else in the package that the battery powers or travels with as equipment. One pack in a carton, or twelve packs in a carton, still UN 3480.

UN 3481. Two situations share that number:

• Packed with equipment. The battery is in the same packaging as equipment it is not installed in. That is the spare pack in the foam cutout next to the robot.
• Contained in equipment. The battery is installed in the device and serves as its power source. That is the pack behind the cover plate.

So the spare is not "basically the same thing" as the installed pack, even though it is the same part number, the same cell, the same BMS, and the same test summary. It is a different shipment inside the same crate.

The part almost nobody explains

Both 3481 situations carry the same UN number, but they do not carry the same packing instruction. Packed-with and contained-in are separate pathways with separate requirements for how the inner packaging is built, how the battery is protected from the equipment, and how the equipment is secured against movement. On the shipping paper, the qualifier in the proper shipping name is doing real work: Lithium ion batteries contained in equipment and Lithium ion batteries packed with equipment are not interchangeable descriptions, even though the UN number in front of them is identical.

No packing group applies to either entry, so if you see a PG listed for a lithium ion battery shipment, that is your first sign the paperwork was assembled by someone guessing.

Here is where this turns into a dock problem. Your warehouse consolidates to save a pallet. Somebody drops the loose spare into the robot crate at 5:40 in the morning because there is room in the foam and the separate carton looks wasteful. The packing instruction the shipment was built around no longer describes the box on the floor. The shipping paper, printed the previous afternoon, no longer describes the box either. Nothing on the outside of the crate changed. The classification did.

The 100 Wh line, and why most shipping advice is not about you

Most of what you will find online about lithium battery shipping was written for laptops. Cells under 20 Wh, batteries under 100 Wh, a small-battery exception, frequently no shipping paper, a lithium battery mark, done.

Your pack is almost certainly not that. A 24V 30Ah pack is 720 Wh. Once you cross 100 Wh, the exception is gone and you are fully regulated: Class 9, a shipping paper, the Class 9 lithium battery label rather than just the mark, and a packing instruction with actual construction requirements attached.

That reframes the whole exercise. For a laptop battery, the UN number is a labeling detail you can clean up later. For a 700 Wh robot pack, the UN number determines how the shipment has to be physically built, and you cannot fix it with a better label after the crate is closed.

The test summary tells you what it is, not what number it is

The UN 38.3 test summary is the document procurement asks for during the supplier audit and then rarely opens again. I have watched teams file it under compliance and never connect it to the shipping desk.

It does not assign a UN number. What it does is describe the cell or battery that was tested, with the model, the watt-hour rating, the physical description, the mass. Two things are worth pulling from it.

First, does the tested article match the thing you are shipping? Same cell with a different BMS, a different housing, or a different capacity is a different article. If your pack is a variant of what was tested, you have a classification problem before you have a UN number problem, and no amount of label selection fixes it.

Second, the summary proves the article passed the tests. It says nothing about whether that article goes out as 3480 or 3481. That answer changes per shipment, based on what else is in the box. The same test summary supports all three configurations I described above, and it will support them again next month when the packaging changes.

What the receiving clerk actually checks

The package gets to the customer's dock. The person checking it in is not a dangerous goods specialist. He has three things in front of him: the label on the box, the shipping paper, and the packing list.

If the shipping paper says UN 3480 and there is a robot inside the crate, he does not argue the regulation with you. He refuses the delivery. If the paper says contained in equipment and the packing list shows a spare that is not installed, he refuses it too, because now he does not know what he is signing for. Either way you have a machine sitting on a dock eleven hundred miles from its install date and a project manager calling you before you have had coffee.

There is a smaller, uglier version of this. The lithium battery mark has a phone number on it, meant to reach someone who can answer questions about the shipment. More than once I have picked up a box and found the number of a supplier we stopped buying from two years ago, still on the mark, still printed off a template nobody owned. That number is the one the freight terminal calls at 2 a.m. when the pallet gets set aside. Worth ten seconds of your attention.

How I actually decide, in order

Four questions, asked in this sequence, every time.

1. Is the battery installed in something it powers? Contained in equipment. UN 3481.
2. Not installed, but sharing the crate with equipment? Packed with equipment. UN 3481.
3. No equipment in the package at all, just packs? Shipped alone. UN 3480.
4. Does the shipment contain more than one of the above? Then it needs more than one line on the shipping paper, and often more than one package, and the inner packaging for each line has to match the line it belongs to.

Question four is the one people skip. A shipment that is legitimately both is not a problem to hide. It is a shipping paper with two entries and two packaging configurations, and the crate either reflects that or it does not.

Two edge cases I will not pretend to have a clean answer for. Unplugging the pack and capping the connector does not move it back to 3480 by itself; it is still installed in the equipment. And when the thing traveling with the pack is barely equipment, a cable and a bracket rather than a machine, the packed-with reading gets arguable. That is a call for whoever signs your dangerous goods paperwork, not a coin flip at the dock.

One thing about air

If the robot ever flies, the UN number stays the same but the packing instruction set changes and the limits tighten. Batteries shipped alone by air carry a state-of-charge restriction, and the reduced-requirement pathways for packed-with and contained-in have per-package limits that a ground shipment will not teach you. Someone flies a demo unit to a trade show, the ground habit goes with it, and the shipment gets stopped. Build the air version once, keep it on file, and stop re-deriving it under deadline.

The thing to actually fix

The UN number is not a property of your battery. It is a property of the box you put it in and what else is in that box with it. Your supplier's test summary does not assign it. Your ERP part master does not assign it. Whoever builds the shipment that morning assigns it, and if nobody told them the rule, they will assign it by instinct, and instinct says the spare is the same thing as the installed pack.

So stop treating this as a labeling problem. Put the configuration on the pick list in plain words. Put it on the pack's warehouse record, so the shipping desk sees contained in equipment or ships alone before the carton is sealed. Write down that a spare does not get consolidated into an equipment crate without someone rewriting the shipping paper, and then enforce it, because the person who breaks that rule will be trying to help.

Check the current text of 49 CFR 173.185 and the current packing instructions against your actual configuration before you sign anything, and get your dangerous goods provider to confirm the gray-area cases in writing. What I can tell you from ten years of docks and refusals is simpler than any of that: I have never had a misclassification caught by an inspector. I have had it caught by a receiving clerk with a clipboard, in a different time zone, on a day I was supposed to be on vacation.