Fire-rated cabinets for lithium-ion batteries explained
The following guide explains what you need to know when assessing and purchasing safe storage and charging systems for lithium-ion batteries. We cover why you need unique, secure 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.
Why do I need special storage for lithium-ion batteries?
Lithium-based batteries offer high performance with a compact design. Their use has dramatically increased in the home, commercial and industrial settings. They are quickly becoming an integral part of storing and using energy. Their use ranges from mobile phones to 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, appropriate measures need to be taken to avoid and limit damage and guarantee insurance cover.
Many insurers now require businesses to put appropriate and adequate protective measures about 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 their hazards.
What can cause lithium-ion battery fires?
Lithium-ion battery fires can start in several 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, creating 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 successfully managing 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 a targeted sprinkler system can prevent the spread of lithium battery fires in high racks. However, the findings from the tests are only valid for small lithium batteries packed in cardboard boxes. The sprinkling of large battery units is 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 by VdS CEA 4001.
Extinguishing agents
Powder extinguishing agents such as aerosols suppress the fire in the batteries. S valuable time can be saved, especially with smaller storage volumes, such as safety cabinets or emergency containers. However, this does not bring about a cooling effect.
Extinguishing granules often used in transport boxes for faulty lithium batteries work to thermally insulate the battery. The extinguishing or insulation effect is immediately active and functions entirely autonomously. A prerequisite, however, is that the batteries are surrounded by a sufficient quantity of granules, which can significantly 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 fire from the surrounding environs for the period specified in the fire-rating. Fire protection works from both the inside and the outside, providing protection from fires within the cabinet and 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 to guarantee Europe's highest level of protection. The fire-rated stores are the first and only construction products of this kind with official ETA approval / CE marking by 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 Efectos, a body designated by the EU.
Safer solutions.
The DENIOS fire-rated store 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. Extinguishing technology specially designed for lithium batteries ensures optimized defensive fire protection.
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 preventive measures must take into account individual circumstances. The fire protection should be appropriate for the particular situation, 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 implemented. 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 most significant, and the effects of thermal runaway are also at their highest. The self-reinforcing reaction of the lithium-ion battery can lead to bursting. This risk can be minimized if safety rules are observed, and the storage and charging conditions are well-matched to the stored goods.
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. Deep discharges can permanently damage them, 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 the effects of aging 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 into the manufacturer's charger prevents over-charging and deep discharge. It is a safety feature that protects the battery's performance 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: a collection of batteries used to store energy.
Electric Vehicle: a vehicle that uses one or more electric motors for propulsion.
Battery Management System (BMS): an electronic system that manages rechargeable batteries.
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.
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