Why battery shipping has its own rules
Batteries store energy and most chemistries can release it violently if abused. The UN Model Regulations classify them as Class 9 (miscellaneous dangerous goods, for lithium) or Class 8 (corrosive, for lead-acid). Air carriers, ocean carriers, and road authorities each adopt the UN base rules with their own modal annexes — IATA DGR for air, IMDG for sea, ADR / DOT / RID for road and rail. The classification doesn't change much between modes, but the packing instructions and labels do.
Section I vs Section II for lithium
IATA splits lithium shipments into two tiers. Section II covers small batteries — individual cell ≤ 20 Wh, individual battery ≤ 100 Wh — which can be shipped on passenger aircraft with reduced labelling. Section I covers everything above the threshold; these are fully regulated dangerous goods, and UN 3480 (lithium-ion shipped alone) is forbidden on passenger aircraft entirely. UN 3481 (lithium in equipment, or packed with equipment) is more permissive because the equipment provides shock and short-circuit protection.
UN 38.3: the test that gates the shipment
Every lithium cell and battery design manufactured for international shipment must pass the UN 38.3 test sequence: altitude, thermal cycling, vibration, shock, external short circuit, impact / crush, overcharge, and forced discharge. As of 1 January 2020, the shipper must hold a UN 38.3 test summary from the manufacturer (or sub-supplier) and produce it on demand. Failure to do so is grounds for a carrier to refuse the shipment.
VRLA: the easy case
Sealed lead-acid (VRLA / AGM / Gel) qualifies as “non-spillable” under UN Special Provision 238 and ships under simplified rules: still a dangerous good, still requires Class 8 markings, but no quantity limit per package and accepted on all modes including passenger aircraft. Flooded lead-acid (VLA) is the harder case — it can spill corrosive electrolyte and is forbidden on passenger aircraft.
When to involve a DGSA
For routine spares (a couple of replacement batteries per quarter), the dealer's freight forwarder usually handles the paperwork. For large shipments, mixed-modal transport, or any case where the rules feel ambiguous — get a certified Dangerous-Goods Safety Adviser (DGSA in EU, equivalent elsewhere) involved early. Penalties for misdeclared dangerous goods are substantial and the carrier can refuse the shipment at any point with no refund.