Original sealed packaging
Cells and batteries alone (UN3480) travel in the original manufacturer packaging. Loose LiPos in a plastic bag are not accepted, and neither is a repack into a mystery bubble mailer.
Lithium hazmat
Can you ship lithium polymer batteries?
A LiPo alone, on surface transport, in the original sealed retail packaging, up to 100 watt-hours per battery. A LiPo inside a device on any US carrier's ground or air service, up to the same 100 Wh limit and no more than eight cells or two batteries per parcel. Damaged or recalled LiPos on no carrier at all. Rules read from USPS Publication 52 Appendix C section 9D on 2026-08-11.
USPS Pub 52 quotedWh caps per cell and per batteryDamaged batteries refused
Two UN numbers, two rulesets
Whether the LiPo travels with its device or alone decides almost every rule that follows.
The UN classification decides the ceiling
Lithium-ion and lithium polymer batteries carry one of four UN numbers depending on chemistry and whether they travel alone or inside a device. LiPo sits under UN3480 (alone) and UN3481 (with equipment). Rules quoted from USPS Publication 52 Appendix C 9D read 2026-08-11.
| UN number | How the LiPo travels | USPS acceptance | Cell / battery limit |
|---|---|---|---|
| UN3480 | Cells or batteries alone | Surface transportation only, in the original sealed retail packaging | ≤20 Wh per cell, ≤100 Wh per battery; 5 lb per mailpiece |
| UN3481 | Cells or batteries installed in or packed with the equipment they are intended to operate | Air or surface, per Publication 52 Appendix C 9D | ≤20 Wh per cell, ≤100 Wh per battery; maximum 8 cells or 2 batteries per mailpiece |
| UN3480 or UN3481, damaged or defective | Any form | Prohibited from air transportation; surface only under Publication 52 restrictions on restricted electronic devices | Sender must mark “Restricted Electronic Device” and “Surface Transportation Only” |
The 100 Wh line is the point at which a battery leaves the excepted lane and becomes fully regulated hazmat. Once the Wh figure crosses that ceiling, USPS is no longer an option and both private carriers require a dangerous-goods contract with declaration, training and specialist packaging that no consumer account carries.
Marking and packaging that has to be on the box
The DOT-approved lithium-battery marking is not an option; it is what identifies the parcel to sorting equipment and handling staff. USPS Pub 52 Appendix C 9D, read 2026-08-11, sets the terms below.
Address-side lithium marking
The DOT lithium-battery mark and, on UN3480 shipments, the text “Surface Mail Only” plus the aircraft-prohibition wording sit on the address side of the parcel. Missing markings are the usual reason a first-time shipper's parcel is refused at the counter.
Terminal protection
Both PHMSA and every carrier require that battery terminals be protected against short circuit. Tape covering exposed contacts is the minimum; individual cell bags or the retail blister pack does the same job.
Terminal contact between a LiPo and any conductive object inside the box is the failure mode this rule addresses. LiPos in transit have started warehouse fires, and the packaging rules are what keep them from being the cargo that does it again.
Private carriers, ground and air
UPS and FedEx both accept lithium-ion and polymer batteries under their own dangerous-goods programmes, and both use the same UN3480 / UN3481 split as PHMSA. Both refuse damaged, defective or recalled batteries on any service. Above the 100 Wh line, both require a fully regulated hazmat shipment prepared under IATA or 49 CFR by a trained shipper on a contract with the carrier's dangerous-goods team; UPS and FedEx publish acceptance criteria and the required forms on their prohibited-items pages.
The device-installed case (UN3481) is the everyday one for a repair shop or an e-commerce return. A drone, a smartphone or a portable tool with the battery inside can move on standard UPS Ground or FedEx Ground alongside the required lithium-battery mark and a shipper's declaration; the “packed with equipment” category adds a bit more paperwork than the installed one, but stays within the same Wh limits.
The consumer parcels our checkout handles
SMKlog quotes battery-in-equipment parcels within the USPS Publication 52 Appendix C 9D and carrier acceptance limits: a device with the LiPo installed, one or two devices per parcel, within the Wh caps above. Our restrictions page follows the carrier rules directly, so a checkout that declines a large loose LiPo is doing so because the tariff declines it, not because we invented a rule; a small device with an installed battery walks through the same checkout as any other parcel.
Above the excepted 100 Wh line, or when the battery is loose in bulk, the parcel belongs on a specialist hazmat shipper account. Freight Review is the route in that case; a human quotes the lane and confirms the DG paperwork is in place before a label prints.
Where these rules come from
- USPS, Publication 52 Appendix C section 9D — Lithium metal and lithium-ion cells and batteries (domestic). Read 2026-08-11.
- PHMSA, Lithium battery shipping regulations — UN3480 versus UN3481 split, small-battery exception. Read 2026-08-11.
- PHMSA / eCFR, 49 CFR 173.185 — the regulatory home of the Wh limits and excepted-quantity provisions. Cross-cited from Publication 52.
Lithium-battery rules move fast, particularly after major cargo-fire incidents. Treat the wording above as what USPS and PHMSA published on the date each was read, and confirm the current tariff and hazmat contract before shipping bulk batteries or anything above the excepted Wh line.
Common questions
Can you ship lithium polymer batteries in the US?
Yes, with limits. USPS accepts LiPo cells and batteries alone (UN3480) only on surface transport in the original sealed packaging, and accepts LiPo packed with or in equipment (UN3481) on both air and surface within Wh caps, per Publication 52 Appendix C 9D read 2026-08-11.
What is the difference between UN3480 and UN3481?
UN3480 covers cells or batteries shipped by themselves. UN3481 covers the same chemistry inside or packed alongside the equipment it powers. The two UN numbers carry different acceptance rules on every US carrier.
What are the watt-hour limits for LiPo?
Twenty watt-hours per cell and one hundred watt-hours per battery for lithium-ion or polymer, per USPS Publication 52 Appendix C 9D. A very small consumer battery threshold sits at 2.7 Wh. Above the 100 Wh line, the parcel becomes fully regulated hazmat.
Can I ship a damaged LiPo?
No. USPS prohibits damaged, defective or recalled lithium batteries from air transportation and restricts them to surface only in additional restrictive terms; UPS and FedEx both refuse damaged lithium batteries under their dangerous-goods programmes.