Lithium batteries power everything from phones to forklifts, and a growing share of UK freight - new batteries, products containing them, and waste electricals heading for recycling - carries them. They are also Class 9 dangerous goods with a failure mode unlike anything else in the trailer: thermal runaway, a self-heating chain reaction that can turn a damaged cell into an intense, hard-to-extinguish fire. Hauliers moving battery loads need to understand what they are carrying and which rules apply.
The government’s dangerous goods guidance describes the mechanism plainly. Thermal runaway of lithium-ion batteries is a phenomenon of chain exothermic reactions within the battery: the reactions cause a sharp rise in internal temperature, the inner structures destabilise and degrade, and the battery fails - venting gas, fire, and heat that can ignite neighbouring cells. The triggers are damage or defect: scorch marks, evidence of leaked electrolyte, a bulging or expanded case. A pallet of undamaged, properly packed new cells is a managed risk; a crushed mixed load containing batteries in unknown condition is a different proposition entirely.
The waste-stream statistics make the risk concrete. Lithium batteries are responsible for approximately 48% - over 200 - of all waste fires occurring in the UK each year, at a cost of £158 million annually to waste operators, the emergency services and the environment. Anyone carrying waste electricals, skip waste or mixed recycling should read that number twice: the fire risk in the waste chain is substantially a battery story.
All dangerous goods transport starts with classification. The UN Model Regulations assign every dangerous substance or article a class defining the type of danger, and a packing group - PG I, II or III - grading the level of danger. Class and packing group together dictate how the goods must be packaged, labelled and carried: inner and outer packaging, packaging materials, marks and labels. Lithium cells and batteries sit in Class 9, miscellaneous dangerous substances.
Responsibility for getting the classification right sits with the consignor - the person or business shipping the goods - who must classify, mark and package them correctly so that every organisation in the supply chain, including the emergency services, understands the hazard. Machinery or equipment containing dangerous goods must be classified using the most appropriate entry in the dangerous goods list, and transport must comply with that entry’s provisions.
The legal framework in Great Britain is ADR - the European Agreement concerning the International Carriage of Dangerous Goods by Road - applied through the Carriage of Dangerous Goods and Use of Transportable Pressure Equipment Regulations 2009 (as amended). ADR sets the requirements for classification, packaging, labelling and certification, plus vehicle, tank and operational requirements.
Waste streams get their own provisions. The transport of lithium cells and batteries - and sodium ion cells and batteries - installed in equipment from private households, collected and handed over for carriage for depollution, dismantling, recycling or disposal, is subject to special provision 670 of the ADR. The guidance on moving small mixed waste from WEEE notes that such waste may contain lithium-ion, lithium metal or sodium ion batteries in unknown condition - damaged, defective, scorched, leaked or bulged - which is precisely the population most prone to thermal runaway. Research cited in the guidance estimated roughly 0.06% by weight of small mixed WEEE is batteries of all types: on a 2-tonne load, perhaps 1.2kg of lithium-ion battery - a handful of laptop-sized packs, but enough to start a fire that takes the load, the trailer and the site with it.
One duty deserves its own paragraph because it is little known: you must report a serious incident resulting from the presence of lithium-ion batteries to the Dangerous Goods Unit at the Department for Transport - dangerousgoods@dft.gov.uk. A vehicle fire traced to a battery load is not just an insurance event; it is a reportable dangerous goods incident.
For general hauliers the working rules reduce to: know whether your load contains batteries - ask the consignor explicitly for waste, WEEE, returns and mixed loads; treat damaged, swollen or scorched battery items as a stop-and-refer condition, not a load-and-go; follow the packaging and marking on the consignor’s documentation rather than improvising; segregate and protect battery loads from crushing; and brief drivers on what a battery event looks like - hissing, smoke, intense localised heat - and on stopping and calling the fire service rather than tackling it. Batteries are everyday freight now, but they are freight that can burn the truck down. Carry them knowingly.