Fire-rated cabinets for lithium-ion batteries explained - what you really need to know.
A guide to what you really need to know when assessing and purchasing safe storage and charging systems for lithium-ion batteries. We cover why you need special, safe storage for lithium-ion batteries; what can cause lithium-ion battery fires; what you can do to protect your staff and business if you handle, charge and store lithium-ion batteries; and safer solutions for your storage and charging needs with lithium-ion batteries. Understand the regulations in the UK and what guidance you need to follow.
Why do I need special storage for lithium-ion batteries?
Lithium-based batteries offer high performance with compact design. Their use has seen a dramatic rise both in the home and in commercial and industrial settings. They are quickly becoming an integral part of how we store and use energy. Their use ranges from mobile phones, through tools to vehicles.
Alongside the many advantages of using lithium batteries there are safety risks. Lithium-ion batteries pose a greater risk of fire and bursting.
Legislation has not caught up with these technological developments. At present there is no unified regulation on safety and accident prevention from legislators. However, to avoid and limit damage and to guarantee insurance cover, appropriate measures need to be taken.
Many insurers are now requiring businesses to put in place appropriate and adequate protective measures with regard to lithium-ion battery storage, handling and charging to protect personnel and premises.
Lithium-ion batteries can develop into significant and unstoppable thermal runaway fires, so carefully considered measures are required to address the hazards that they pose.
What can cause lithium-ion battery fires?
Lithium-ion battery fires can start in a number of ways:
Internal defects (materials defects, construction issues, contamination)
Physical damage (during assembly, during transportation, in handling, waste disposal or through accidents)
Electrical misuse (over-charging, over-discharging, short-circuits)
Thermal abuse (exposure to high temperatures)
Thermal runaway typically occurs in the following scenarios:
Temperature increases
Venting or off-gassing
Flare
Steady burn
Flash fireball
Explosion
Thermal runaway starts in a single cell and creates a domino effect on adjacent cells.
What can I do to protect my business?
If you handle, store, use, or charge lithium-ion batteries in your business, there’s no question: you need to take action to protect your staff and your business.
There are 3 key areas to focus on:
Detection & monitoring
Suppression & extinguishing
Protection & separation
Detection & Monitoring.
Pre-fire conditions in lithium-ion batteries can be detected by monitoring several phenomena such as gas & vapour emissions and abnormal temperatures.
Monitoring technology helps you quickly and effectively identify any issues. This means earlier action can be taken to mitigate any risk.
Suppression & extinguishing.
Evidence has shown that the key to successful management of a lithium-ion battery fire is first suppressing or extinguishing the fire and then cooling the adjacent cells that make up the battery pack or module.
Sprinkler systems
Tests by the American property insurer FM-Global and the German Insurance Association (GDV) have shown that the spread of lithium battery fires in high racks can be prevented by a targeted sprinkler system. However, the findings from the tests are only valid for small lithium batteries packed in cardboard boxes. The sprinkling of large battery units is nevertheless advisable, as although the fire is not usually extinguished at the individual battery, the spread to neighbouring batteries can be slowed, if not prevented.
The recommended maximum storage is 50 kWh per unit (e.g. one Euro pallet). This is equivalent to Hazard Level II. The sprinkler system must be designed in accordance with VdS CEA 4001.
See the DENIOS sprinkler product.
Extinguishing agents
Powder extinguishing agents such as aerosols suppress the fire at the batteries. Especially with smaller storage volumes, such as safety cabinets or emergency containers, valuable time can be saved. However, this does not bring about a cooling effect.
Extinguishing granules, which are often used in transport boxes for faulty lithium batteries, they work to thermally insulate the battery. The extinguishing or insulation effect is immediately active and functions completely autonomously. A prerequisite, however, is that the batteries are surrounded by a sufficient quantity of granules, which can greatly restrict handling.
Separation.
Tested, proven and certified fire-rated cabinets allow lithium-ion batteries to be stored and charged separately from day-to-day operations.
These fire-rated facilities enable the separation of the source of a fire with the surrounding environs for the time period specified in the fire-rating. Fire-protection works from both the inside and the outside, providing protection from fires within the cabinet and also reducing the potential escalation of an incident if a fire occurs outside of the cabinet.
DENIOS tests all fire-rated products for 120-minute fire resistance in order to be able to guarantee the highest level of protection throughout Europe. The fire-rated stores are the first and so far only construction products of this kind with official ETA approval / CE marking in accordance with European Regulation (EU) No. 305/2011. In addition, they have been successfully tested and classified as a complete system in a fire test by the French testing institute Efectis, a body designated by the EU.
Safer solutions.
The DENIOS fire-rated store WFP Li-Ion offers certified fire protection. By equipping the unit with air-conditioning technology for outdoor installation and monitoring electronics, additional precautions for preventive fire protection can be taken. With extinguishing technology specially designed for lithium batteries, optimum defensive fire protection is ensured.
We recommend using aerosol extinguishing technology, if there are several storage levels, as the extinguishing agent is then better distributed in the room and over the storage levels.
Protective and preventative measures must take into account individual circumstances. The fire protection should be appropriate for the particular situation and use and specific hazard configuration.
A risk assessment is required to determine the nature and extent of the fire challenges and the safety measures that should be put in place. DENIOS recommends an on-site visit to get a clear picture of the site and operational requirements.
Lithium-Ion Battery - Charging Risks Reduced.
Safety when charging.
Charging lithium-ion batteries poses a greater risk than simply storing them. This is especially true if the batteries are damaged. The greatest danger is if a short circuit occurs in the battery when fully charged. This is when the stored energy is at its greatest and therefore the effects of thermal runaway are also at their highest. The self-reinforcing reaction of the lithium-ion battery can lead to bursting. If safety rules are observed and the storage and charging conditions are well matched to the stored goods, this risk can be minimised.
Do not charge damaged batteries.
Damaged or defective batteries should be removed immediately from storage and production areas. A defect is often not visible and it is therefore not easy to assess the condition of a battery. To be safe, you should always store batteries of unknown condition in a separate quarantine store. This store must be taken into account in the operational fire protection design.
Avoid deep discharge.
The charging of lithium-ion batteries is also critical if they have not been used for a long time or have been fully discharged. They can be permanently damaged by deep discharges, causing a chemical reaction during charging. This is why, for example, garden tools with rechargeable batteries have a trickle charge, which corresponds to a charge level of approx. 30%. This reduces aging effects and prevents deep discharge.
Only charge lithium-ion batteries in a monitored environment.
Cold or high temperatures and high humidity can also cause damage to the cells. Therefore, only charge lithium batteries under supervision, at room temperature and in a fire-rated location.
Only use certified chargers, or chargers from the manufacturer.
In most commercially available rechargeable batteries, the battery management system (BMS) integrated in the manufacturer's charger prevents over-charging and deep discharge. It is a safety feature that protects the performance of the battery and prevents defects. The BMS can also be part of the battery itself.
Key definitions
Lithium-ion Battery: a rechargeable battery that uses lithium-ions as the primary component of its electrolyte.
Energy Storage: the capture of energy produced at one time for use at a later time.
Energy Storage System: collection of batteries used to store energy.
Electric Vehicle: vehicle which uses one or more electric motors for propulsion.
Battery Management System (BMS): electronic system that manages a rechargeable battery.
Thermal Runaway: exothermic chemical reaction generating more heat than is being dissipated
Thermal Propagation: where a single battery cell thermal runaway spreads to neighbouring cells.
Fire Tetrahedron: elements required to sustain a fire - fuel, heat, oxygen and a chemical chain reaction.
Off-gassing: venting of flammable/ toxic electrolyte vapours.
Find out more about fire-rated cabinets and the UK regulations and guidance for storing and handling flammable materials. See what standards the DENIOS flammable storage cabinets adhere to.
More DENIOS expertise on similar topics.
The specialist information on this page has been compiled carefully and to the best of our knowledge and belief. Nevertheless, DENIOS Ltd cannot assume any warranty or liability of any kind, whether in contract, tort or otherwise, for the topicality, completeness and correctness either towards the reader or towards third parties. The use of the information and content for your own or third party purposes is therefore at your own risk. In any case, please observe the locally and currently applicable legislation.
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