Storing Lithium Batteries Safely: Warehouses, Yards and Outdoor Sites

1. Why Storage Is Where Battery Fires Actually Start

Transport gets most of the regulatory attention, and for good reason: the dangerous goods codes are detailed, harmonised and enforced at the roadside. But a battery spends only a fraction of its life on a vehicle. The rest of the time it is stored: in a distribution centre awaiting dispatch, in a service workshop awaiting diagnosis, on a recycler's yard awaiting processing, or in a container next to a construction site awaiting installation. That is where the hours accumulate, and hours are what turn a latent defect into an event.

Three factors make storage the higher-exposure phase for most organisations:

• Dwell time. A pack in transit is exposed for hours or days. A pack in a returns area may sit for weeks. A cell with an internal defect, or one that was quietly damaged during handling, has far more time to develop a fault while nobody is watching it.
• Damaged returns. Reverse flows bring back exactly the batteries most likely to fail: warranty claims, recalled products, accident-involved vehicles and packs removed because they behaved abnormally. Anyone who has run a returns programme for EV packs knows that the condition of what arrives is often unknown until someone has inspected it.
• Mixed stock. New, used and suspect batteries end up side by side because they share a SKU, a customer or a free bay. A single failing unit then sits next to a large quantity of healthy fuel.

The physics do not change between a trailer and a rack. Once a cell passes its decomposition thresholds, heat and gas spread to its neighbours, and understanding cell-to-cell propagation inside a pack is the starting point for every storage decision that follows. What does change is the environment: a building full of combustible goods, people working nearby, and a fire service that may arrive to find an event that has been developing unseen for some time.

2. Know What You Store: Condition, Chemistry and State of Charge

A storage plan is only as good as the inventory behind it. Before deciding on compartments, distances or detection, sort your stock by the factors that drive its risk. In practice four condition categories cover almost every site:

The last row is the one most sites get wrong. A battery with no history is not a healthy battery; it is an unassessed one. Making quarantine the default for unknown condition removes the temptation to rack an unexamined return with new stock because the quarantine bay is full. The criteria for promoting a battery out of quarantine should be written down and should mirror the logic used for transport, so that deciding whether a pack is damaged or critical is done once and recorded, rather than repeated informally by each shift.

2.1 State of charge

State of charge (SoC) is the single most controllable risk factor in storage. A cell at lower SoC holds less energy to release and tends to fail less violently. For long-term storage, the battery manufacturer's recommended storage SoC should be followed, and new stock arriving at high SoC should be identified. Lower SoC reduces severity but does not prevent failure, so it complements rather than replaces the other measures. Note that insurer guidance treats SoC as a parameter in its own right: protection options in insurance data sheets can depend on it.

2.2 Chemistry and mixed stock

Record the chemistry as well as the condition. LFP, NMC and NCA cells behave differently in failure, and sites increasingly hold non-lithium technologies alongside lithium stock. Where sodium-ion products enter the same warehouse, do not assume they can be treated identically: check the product documentation and understand how sodium-ion cells are classified for carriage before they move on. For recyclers, the same discipline applies to mixed collection streams, and organised reverse logistics flows for recycling start with sorting at the point of intake rather than at the shredder.

3. The Rulebook: What Applies in the Netherlands, Germany and the Insurance Market

Unlike transport, storage of lithium batteries is not governed by a single international code. What applies depends on the country, the permit and, in practice, the insurer. Four documents come up most often in European and international projects.

3.1 Netherlands: PGS 37-1 and PGS 37-2

The Dutch Publicatiereeks Gevaarlijke Stoffen contains two lithium documents, both adopted in December 2023 by the Bestuurlijk Omgevingsberaad. PGS 37-1 covers energy storage systems (installed lithium-ion systems of 20 kWh and above). PGS 37-2 covers the storage of lithium-containing energy carriers: batteries for laptops, e-bikes, electric and hybrid vehicles and similar applications.

PGS 37-2 is not yet a directly binding rule. It describes the state of the art and is applied through permit conditions and the duty of care under the Omgevingswet framework. That is changing: a proposed amendment to the Besluit activiteiten leefomgeving (Bal) would designate the storage of lithium batteries as an environmental activity in its own right. Consultation closed on 28 April 2026 and implementation is expected around 2028. In the meantime, a competent authority or safety region can, and often does, use PGS 37-2 as the benchmark when assessing a site.

The document addresses themes that will be familiar from the rest of this guide: classification of what is stored, separation and fire compartmentation, detection and alarm follow-up, handling of damaged batteries, and emergency preparedness. Because the specific values depend on quantities, building type and local circumstances, the full text and the competent authority are the only reliable sources for figures.

3.2 Germany: VdS 3103 and VdS 3856

VdS 3103 (edition 2019-06), "Lithium batteries", is loss-prevention guidance published by the German insurers. It is not law, but it can be applied within insurance contracts, which in practice gives it real weight on German sites. It groups batteries by size and power, and its focus is on providing and storing batteries in production and storage areas. VdS 3856 deals with sprinkler protection for large quantities of lithium batteries.

3.3 United States and international insurers: NFPA 855 and FM Global

NFPA 855 is frequently cited in storage discussions, but its subject is the installation of stationary energy storage systems, not general warehouse storage of battery stock. For warehouse and bulk storage, the prescriptive criteria sit in FM Global Data Sheet 8-1, which classifies lithium-ion batteries as a stored commodity and links protection to factors such as packaging, state of charge, storage height and arrangement. FM Global Data Sheet 5-33 covers lithium-ion battery energy storage systems.

4. Warehouses: Compartments, Racking, Detection and Gas

Inside a building, the aim is to stop one failure from becoming a building fire, and to make sure people are not exposed to the gas while that is being achieved. Five areas deserve attention.

4.1 Water versus thermal runaway

A lithium-ion cell in runaway generates its own heat and, in common cathode chemistries, its own oxygen. Water applied from above therefore does not extinguish it in the conventional sense. What water does well is cool adjacent packs and structure, which slows propagation and protects the building. That is why sprinkler guidance for battery storage, including VdS 3856 and the FM Global data sheets, focuses on controlling the fire's growth and protecting the surroundings. Plan for the possibility that a pack will continue to react, or re-ignite, after the visible fire has been knocked down.

4.2 Gas in enclosed buildings

Venting cells release a flammable and toxic mixture, including hydrogen fluoride released by venting cells. Outdoors this disperses; inside a closed hall it accumulates. The practical consequences for a warehouse are:

• Staff should not investigate a suspected battery event by walking up to it. The emergency plan should say who leaves, by which route, and who calls the fire service.
• Smoke extraction and ventilation strategies should be discussed with the fire service, because flammable vent gas changes the picture compared to an ordinary fire.
• Fire water that has been in contact with burning batteries may be contaminated. Where possible, consider how run-off would be retained.
• Goods and surfaces exposed to smoke from a battery fire may carry fluoride residues and should be assessed before reuse.

4.3 Charging and housekeeping

Charging areas are a frequent ignition point and should be separate from bulk storage. Beyond that, the basics matter more than any single technology: keep aisles clear, keep packaging and pallets away from battery zones, protect terminals against short circuit (caps, tape or original packaging), and remove damaged items from the general stock immediately rather than at the end of the shift.

5. Yards and Outdoor Sites

Outdoor storage solves some indoor problems (gas disperses, the building is not at risk) and introduces new ones. Batteries are stored outdoors on recycling yards, at vehicle compounds, at dealers and workshops, on construction sites and at energy projects awaiting commissioning, where suppliers increasingly arrange temporary on-site storage of BESS modules between delivery and installation.

• Weather. Rain and standing water can cause corrosion and short circuits. Store on a hardened, drained surface and use enclosures that keep water out.
• Sun and heat. Direct sun on a dark container can raise internal temperatures well above ambient. Shade, ventilation and light-coloured surfaces help; parking a full container against a south-facing wall does not.
• Distance to buildings and boundaries. An outdoor battery fire still radiates heat and produces a plume. Keep storage away from buildings, other combustible stock and the site boundary, and agree the distances with the competent authority rather than estimating them.
• Fire service access. Responders need to reach the storage area with vehicles and to approach from upwind. Check access routes, gate keys, hydrant positions and turning space, and keep them clear.
• Security. Batteries attract theft, and theft attempts cause damage. Fencing, lighting and camera coverage protect both the stock and its condition.

Remote and temporary sites face the same issues in a harsher form. Military users, for example, deal with battery stock held at forward depots, where there is no sprinkler system, no building to compartment and often no fire service nearby. In those settings, the enclosure around the battery is effectively the whole fire strategy.

6. Damaged and End-of-Life Batteries

Damaged and end-of-life batteries deserve their own procedure, because they combine the highest likelihood of failure with the least information about their internal state. Volumes are rising, and so are obligations: Regulation (EU) 2023/1542 raises collection and recycling expectations across the battery value chain, which means more end-of-life batteries waiting in more places before they are processed.

6.1 The quarantine zone

A quarantine zone is a physically separate, clearly marked area for batteries that are damaged, defective or of unknown condition. It should have its own detection, be located away from bulk stock and building escape routes, and be accessible to the fire service. Each item in it should carry a tag with its arrival date, source, known history and the date of its last check. Where possible, each item should be individually contained so that one failure does not involve its neighbours.

6.2 From arrival to dispatch

The handover from storage to transport is where many sites lose control. A pack that has been quarantined loose on a pallet must be loaded into suitable packaging, by hand, at the moment it is about to leave. Planning the storage method with the eventual transport in mind avoids that extra handling of the least predictable item on site.

7. Containment as a Storage Measure

Most storage measures act on the building: walls, distances, sprinklers, detection. Containment acts on the battery itself. A sealed enclosure that can hold a full thermal runaway changes several assumptions in a site's risk assessment at once: the heat that reaches neighbouring stock, the gas that reaches people, and the need to move a failing battery out of the area.

BUNCKER® containment packaging is designed for both transport and storage, and is suitable for indoor and outdoor use. Its relevant properties for a storage plan are:

• Patented bell jar architecture. The battery stands on a base and the containment body lowers over it and seals, with no sand, vermiculite or other filler material.
• HF neutralisation. The Fibercon Altilium® CP Blanket (FACB) neutralises hydrogen fluoride in the vent gas, which matters most inside buildings.
• Outer surface below 100 °C during a full thermal runaway, so the event remains inside the unit rather than heating the rack or pallet next to it.
• Sized by energy. Six models from 45.8 kWh to 200 kWh, all UN LP906 certified and valid under ADR, IMDG and RID, so the same unit serves the quarantine bay and the journey to the recycler.

For sites handling batteries in many conditions, the side-loading BUNCKER® Model SDR is described as one system for transport, storage and handling, inside and outside, for batteries in any status. For larger packs and modules, the rule of thumb is matching containment capacity to pack energy: specify against the full kWh content of what you store, not against an average.

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8. Site Checklist and Emergency Plan

Use this list as a starting point for an internal audit. It does not replace the guidance that applies to your site, but it covers the questions an authority, fire service or insurer is likely to ask.

8.1 Storage checklist

• ✅ An up-to-date inventory of battery stock by location, quantity, chemistry and condition category.
• ✅ Agreement on which guidance is the benchmark for the site (PGS 37-2, VdS, FM Global or other), recorded in writing.
• ✅ State of charge for stored stock in line with the manufacturer's storage recommendation.
• ✅ A marked quarantine zone for damaged, defective and unknown-condition batteries, with its own detection.
• ✅ Quantity limits per zone, and separation or fire-rated compartments between battery zones and other goods.
• ✅ Terminals protected against short circuit on all loose batteries and modules.
• ✅ No battery storage near heat sources, charging stations or in direct sun.
• ✅ Detection appropriate to the zone (smoke, heat and, where relevant, off-gas), with a defined response to every alarm.
• ✅ Outdoor storage on hard standing, weather-protected, at an agreed distance from buildings and boundaries, and secured.
• ✅ A documented inspection routine for quarantined items, with dates and outcomes recorded.
• ✅ Clear fire service access routes, kept free at all times.
• ✅ Containment units inspected through the manufacturer's certified service programme.

8.2 Emergency plan

• ✅ Evacuation routes and assembly points that keep people out of a potential gas plume.
• ✅ A pre-agreed briefing for the fire service: what is stored where, in what quantities and in what condition.
• ✅ A site plan showing battery zones, quarantine area, containment units and isolation points, kept at the entrance.
• ✅ A rule that staff do not approach, move or open a battery showing signs of failure.
• ✅ A plan for contaminated fire water and residues after an event.
• ✅ Joint exercises or site visits with the local fire service at least once, and again after significant changes.