The Southeast U.S. has become the operational center of North American battery manufacturing, and the regulatory framework around lithium battery freight has become correspondingly load-bearing. Hyundai Metaplant America in Bryan County, Georgia began production in 2024. SK Battery is shipping at scale from Commerce, Georgia. Volvo's Charleston-area assembly is online. Scout Motors is ramping in Blythewood, South Carolina for 2026 production. BMW Spartanburg's supply chain absorbs cell volume across the I-26 corridor. Redwood Materials is building reverse-logistics capacity in the same geography. Most of the cells feeding these plants arrive in containers at the Port of Charleston or the Port of Savannah, and every one of those containers moves under the same body of regulation.
This article walks through that regulation in operating terms — the four UN numbers, the 49 CFR § 173.185 framework that governs them domestically, the IMDG overlay that governs them at sea, and the audit-risk surface that opens up at every mode change between origin and final assembly.
The UN-number landscape, in 90 seconds
Four UN numbers cover the universe of lithium battery freight, and getting them right is the difference between a clean Bill of Lading and a CBP hold.
UN3480 — lithium-ion batteries shipped alone. This is the dominant classification for cell shipments arriving at Charleston or Savannah destined for an OEM battery plant. Cells in trays, modules, or packs, moving as freight in their own right with no host equipment.
UN3481 — lithium-ion batteries packed with equipment, or contained in equipment. A battery installed in a vehicle, a tool, or a stationary energy storage cabinet falls here. The packaging instructions and exception thresholds are different from UN3480, and the marking requirements on the outer package change accordingly.
UN3090 — lithium metal batteries shipped alone. Less common in the EV manufacturing flow but relevant for specialty applications and certain stationary chemistries. The hazard profile is more sensitive than lithium-ion; the regulatory thresholds are tighter.
UN3091 — lithium metal batteries packed with or contained in equipment. The lithium-metal analog to UN3481.
The distinction matters because each of the four numbers carries its own packaging instruction, its own exception threshold for the small-cell and medium-cell carve-outs, and its own marking and labeling requirements. A shipper who classifies a UN3480 load as UN3481 because the cells are pre-installed in a tray frame may end up with a non-conforming declaration that the receiving carrier rejects on inspection.
The 49 CFR § 173.185 framework
Domestically, lithium battery transport is governed by 49 CFR § 173.185 — the section that defines the exception thresholds and the packaging instructions for all four UN numbers. Operating-grade familiarity with this section is what separates a hazmat-tier carrier from a generalist.
The section establishes three operating tiers. Small-cell exceptions apply to cells below 20 Wh and batteries below 100 Wh — these clear under reduced packaging and marking requirements when shipped under defined unit weights. Medium-cell exceptions apply between those thresholds and the full Class 9 line, with intermediate packaging requirements. Full Class 9 treatment applies to anything above the thresholds — and for the cell shipments arriving at Charleston and Savannah for the Hyundai Metaplant, SK Battery, and Volvo flows, the freight is virtually always full Class 9.
Common shipper mistakes cluster in three areas. First, mis-classifying packed-with-equipment versus packed-alone — a tray of cells with a frame is still UN3480 if the frame is not the equipment the cells power. Second, misapplying the small-cell exception to a load that crosses the threshold on aggregate weight even though individual cells are under the per-cell limit. Third, missing the lithium content threshold entirely on UN3090 / UN3091 freight because the gram-of-lithium calculation was not performed on the actual chemistry.
The receiving carrier — Ramar or anyone else operating at this regulatory tier — verifies all of this on inspection at the gate. A miscalled load comes off the chassis and goes back to the shipper.
The IMDG overlay for ocean carriage
Cells arriving by container at Charleston, Savannah, Wilmington, Norfolk, or Jacksonville moved under the International Maritime Dangerous Goods code for the entire ocean leg. The IMDG declaration is generated at origin — typically by the manufacturer's Korean or Chinese export-compliance team or the origin freight forwarder — and travels with the container through the vessel's stowage plan, the receiving port's hazmat manifest, and the terminal's hazardous-cargo gate procedure.
Three IMDG documents matter operationally for the receiving drayage carrier. The Dangerous Goods Declaration is the manufacturer's or forwarder's certification that the contents are correctly classified and packaged. The Container Packing Certificate confirms that the container itself is properly loaded, blocked, and braced for ocean transit. The vessel stowage plan shows where on the ship the container rode and what other dangerous goods were segregated from it. A receiving carrier reviews all three before accepting drayage. If the documents do not match the placards on the box, the load does not move until the discrepancy is resolved.
For UN3480 and UN3481 freight, IMDG Class 9 placarding is mandatory, and stowage category A applies — the box may ride above or below deck under standard segregation rules. For UN3090 and UN3091, the stowage rules tighten and segregation from Class 4 oxidizers and Class 5 organic peroxides becomes operationally relevant.
The transload moment
The mode change is where audit risk concentrates. Imported cells transit ocean-mode under IMDG, then transition to over-the-road mode under 49 CFR for the inland leg. The documentation, the placarding, and sometimes the packaging configuration all change in the transload yard.
If a container is drayed direct from the terminal to the consignee — a Hyundai Metaplant inbound, an SK Battery inbound, a Volvo inbound — the change is effectively documentary. The IMDG declaration is supplanted by a 49 CFR-conformant Bill of Lading and shipping paper, the Class 9 placards remain, and the box rolls. If the container is broken at a transload facility — cells removed from the marine container, restuffed into a domestic trailer, possibly reconfigured for plant-side delivery sequence — the regulatory regime changes underneath the freight, and every requirement of 49 CFR § 173.185 applies to the new packaging configuration.
This is where shippers most frequently lose chain of custody. A multi-vendor handoff at the transload yard means new shipping papers, new placards, new bracing, and a new operator picking up the regulatory accountability. The integrated model — single operator, single USDOT, single chain of custody from terminal pickup through plant delivery — collapses that exposure into one accountable party.
Atlantic Coast port-specific considerations
The Southeast battery corridor draws on three primary ports, each with operating characteristics that matter for lithium-battery freight.
Savannah's Garden City Terminal is the largest single-container facility in North America at roughly 1,200 acres, with channel depth at 47 feet following the 2022 Savannah Harbor Expansion Project. The Mason Mega Rail expansion that came online in 2021 doubled rail capacity and provides direct intermodal lanes to Memphis, Atlanta, Dallas, and Chicago — relevant for any cell flow that needs to relay from the port to an inland transload before final OTR delivery. For the Hyundai Metaplant in Bryan County, Savannah is effectively the home port; for SK Battery in Commerce, Georgia, Savannah is the inbound-cell origin and inland rail relay is operationally routine.
Charleston carries 52-foot channel depth at the Hugh K. Leatherman Terminal, which opened in 2021 with full ULCV (Ultra-Large Container Vessel) capability — meaningful because the largest cell carriers from Korean and Chinese export terminals increasingly arrive on ULCV-class vessels. South Carolina Ports Authority moves roughly 2.6 million TEUs annually with around 250,000 hazmat-classified, and the Charleston-area Volvo plant, the Scout Motors Blythewood ramp, and the BMW Spartanburg supply chain together anchor Class 9 lithium battery as a heavy and growing lane.
Wilmington at 42-foot channel handles a smaller but operationally relevant share, particularly for inland Carolinas distribution and for FTZ #66-eligible bonded staging when duty-deferral is a procurement consideration.
For battery-plant supply-chain managers planning multi-port redundancy, the operating math is roughly: Savannah for ULCV-scale Korean import volume relayed inland; Charleston for ULCV-capable freight destined for the I-26 supply corridor; Wilmington for smaller-cell volume or FTZ-bonded lanes.
Reverse logistics — retired batteries
Virgin-cell freight is one half of the lithium-battery logistics picture. The other half is retired batteries — packs and modules pulled from end-of-life vehicles, warranty returns, and stationary storage decommissions, moving to recyclers like Redwood Materials.
The regulatory regime is different. RCRA — the Resource Conservation and Recovery Act, administered by EPA — governs hazardous waste handling, and a retired lithium battery is, at the federal level, a universal-waste-eligible material when handled under the appropriate stream. The shipping papers change: a uniform hazardous waste manifest replaces the standard Bill of Lading on certain flows. The packaging requirements account for damaged, defective, or thermally-compromised cells (DDR — damaged, defective, recalled — provisions in 49 CFR § 173.185(f)). Thermal-runaway risk is materially higher than for virgin cells, and the receiving carrier's protocols reflect that.
As the EV fleet ages — and as the Hyundai, SK, Volvo, Scout, and BMW production volumes from 2024-2026 begin reaching their first warranty returns and end-of-first-life decommissions in the late 2020s — reverse-logistics volume in the Southeast corridor will scale meaningfully. The carriers that will absorb that volume are the carriers that are operating UN3480 / UN3481 freight today and that have the RCRA-aware documentation discipline to extend cleanly into retired-battery streams.
What to verify before tendering a lithium battery load
Before tendering a Class 9 lithium battery load to any carrier, supply-chain managers and freight-forwarder hazmat coordinators should verify the following operationally:
TWIC credentials for any driver or crew touching freight inside the secure terminal perimeter at Charleston, Savannah, Wilmington, or Norfolk. No TWIC, no terminal access — the load does not move.
PHMSA registration under 49 CFR § 107.601 et seq. — the carrier must be currently registered as a hazmat shipper or carrier with PHMSA and hold the relevant hazmat-endorsement on the operating authority.
IMDG familiarity at the dispatch level. The dispatcher receiving the import should know how to read the Dangerous Goods Declaration and Container Packing Certificate, identify mismatches against the physical placarding, and escalate before the load leaves the gate.
Segregation discipline per § 177.848 if the carrier is co-loading other hazmat classes on the same trailer. Class 9 lithium batteries segregate against certain other classes; the carrier's dispatch and bracing crews should not need a refresher to handle that table.
Thermal-runaway protocols — the carrier's response procedure if a cell goes into thermal runaway in transit. A real answer involves driver training, suppression equipment on the tractor, and a defined emergency-response chain of contact. A vague answer is a risk indicator.
Single chain of custody — whether the carrier can carry the freight from terminal pickup through plant-side delivery under one USDOT, one set of shipping papers, and one accountable dispatcher, or whether the load will hand off through brokers and sub-contracted draymen. The integrated chain is the audit-resistant chain.
The Southeast lithium battery flow is going to grow for the next decade. The regulatory framework that governs it is stable, well-documented, and operationally workable for any carrier that takes the time to build to it. Plant supply-chain managers, freight forwarder hazmat coordinators, and OEM logistics PMs who verify the items above before tendering a load will spend materially less time resolving documentation drift, terminal rejections, and post-incident audit exposure than those who treat lithium battery freight as ordinary Class 9 hazmat.