FAQs on Lithium-ion Batteries
Lithium-ion (Li-ion) batteries are everywhere. They provide power for smartphones, PCs, cordless screwdrivers, robotic lawnmowers, e-bikes and cars. Lithium batteries sometimes store enormous amounts of energy in a small space. In the event of damage, production errors or incorrect handling, the charged energy can be released suddenly in a “thermal runaway” and cause serious fires. DENIOS is an expert provider of safe storage for Li-Ion batteries. On this page we are answering the most commonly asked and important questions about the fire hazards and the best practices in storing and handling of Li-Ion battteries.
Lithium batteries can differ in their cell chemistry - there are e.g. B. Lithium polymer and lithium iron phosphate batteries. They can also differ in their performance (number of cells built into the battery).
Although certain compositions are generally considered to be safer, there are no statistics on cell chemistry that confirm an increased or decreased risk of fire for certain types of batteries. The German Association of Property Insurers (VdS) differentiates between performance classes (low, medium and high performance) when assessing risk. In practical terms, the highest fire risk comes from a defective battery.
According to the requirements of the VdS (German Association of Damage Insurers), all lithium metal energy storage devices with > 2g Li and ≤ 12kg gross per energy storage device are considered to be medium-capacity lithium batteries. For lithium-ion energy storage devices, > 100 Wh and ≤ 12kg gross per energy storage device are specified. Medium-capacity lithium batteries are installed in pedelecs, e-bikes, e-scooters or larger garden tools, for example. It is particularly important to know whether a product is classified by the VdS as a lithium battery of medium performance, since the VdS specifications require stricter safety precautions for the storage of lithium batteries from medium performance classes upwards.
A so-called increase in risk usually has to be reported to the property insurer - i.e. the deviation from the originally insured condition. A good example is the bicycle dealer who has so far mainly sold classic bicycles and now has many e-bikes in its range. However, the use of battery-operated devices can also represent an increased risk in other contexts. In case of doubt, we recommend that you consult your property insurer in order to clarify the situation on a case-by-case basis and to agree on suitable safety concepts for lithium batteries.
In contrast to hazardous material registers, a battery register is not required by law. Nevertheless, it makes sense to keep a battery register in order to be able to better estimate the number of Li-Ion batteries in operation and the resulting risk. This can provide you with valuable information for your risk assessment, from which you can derive suitable safety measures for lithium batteries.
So far there is no legal regulation as to the maximum number of lithium batteries that can be stored in buildings. Your property insurer will provide specifications for this.
Lithium-ion batteries should not be fully charged before storage in order to prevent the battery from aging quickly. In addition, a smaller amount of stored energy can also reduce the severity of the reaction in the event of a fire.
Yes, it makes sense as it significantly reduces the risk of short circuits. However, the contacts can only be masked on single cells with open poles. If the contacts are protected by the battery housing, masking is not possible.
Lithium-ion batteries should ideally be stored in lithium storage cabinets or lithium storage rooms at cool temperatures. The state of charge (SoC) of the lithium batteries should be between 30% and 50% and should be monitored regularly to prevent total discharge. If the charge level is below 5%, the respective lithium battery should be recharged in order to avoid damage caused by the natural discharge process. This is individual and depends on various factors: temperature (higher temperatures favor a faster discharge), original state of charge and cell chemistry. With some products such as B. Robotic lawn mowers have special wintering functions with which the battery management system carries out automatic trickle charging. As a rule, however, a regular manual check is necessary.
The German Association of Property Insurers (VdS) stipulates a structural or spatial separation for the storage of lithium batteries, whereby different safety distances apply depending on the performance class. Storage or charging cabinets for lithium batteries provide a high standard solution in practice, as they are best and easiest to integrate into production operations. With a charging cabinet, there are defined charging locations where employees can store their devices for charging. Otherwise, the employees would always have to make sure to keep the safety distance required on a case by case basis - this variant is unsafe, however, as it is difficult to organise and control.
There is no standard statutory or insurance-related quantity limit. In practice, the size and structure of the battery cabinet determine the possible storage volume and weight (load capacity of the storage levels). The SafeStore storage cabinet from DENIOS, for example, enables lithium batteries with a total weight of 75 kg per storage level to be stored. The power consumption of the chargers is also relevant when choosing a charging cabinet. For example, 3 x 16 A are available in the DENIOS SmartStore charging cabinet. If the lithium-ion cabinet has an integrated extinguishing system, the operating instructions provide information on how much storage space may have to be kept free in order to ensure optimal extinguishing in the event of a fire.
For the storage of smaller quantities of lithium-ion batteries outdoors, DENIOS offers the compact RFP 115 Li-Ion fire protection storage facility.
Charging lithium batteries
There is an increased risk of fire when charging lithium-ion batteries. The danger is particularly great when a battery with a critical defect or with a defective charger is charged.
The charger must be compatible with the lithium batteries used and should be considered suitable by the manufacturer of the lithium batteries. Usually these are the manufacturer's chargers. We only advise the use of approved or manufacturer authorised charging units.
The charging of a lithium battery should always be monitored. However, when charging Li-ion batteries during non-operational periods, for example at night or on the weekend, personal monitoring by employees is not guaranteed. Therefore, for insurance reasons, among other things, it makes sense to use a professional charging cabinet such as the SmartStore from DENIOS, which is designed for the safe charging of lithium batteries.
Handling critical lithium batteries
The greatest danger comes from defective lithium batteries. However, a defective Li-ion battery is often difficult to detect. Internal defects are not necessarily visible from the outside of the battery. The charger may detect a defect - but you shouldn't completly rely on this. External signs of defective lithium batteries are, for example, a damaged housing (signs of mechanical damage) or an inflated housing (signs of thermal damage).
In the event of significant external damage to a lithium battery, the battery should be separated immediately and disposed of. A quarantine container or a transport box approved for defective or damaged lithium batteries is suitable for this.
In practice, it happens again and again that a device powered by lithium-ion batteries falls to the ground. Impact can cause mechanical damage - depending on external circumstances such as the height of fall, nature of the ground or the design of the device (is it a robust quality product or an inferior product?). If a cordless device has been dropped, you should first check it visually: Has the housing cracked? Is the device still functional? Is the charger reporting a problem? Badly damaged devices should not simply be repaired with tape, but either professionally checked and repaired or disposed of.
Fighting lithium battery fires
The cause of fires in lithium-ion batteries is always a short circuit within a cell, which leads to thermal runaway. This short circuit can trigger various events, e.g. overcharging by the charger, heating or ingress of foreign bodies.
The release of gasses or smoke from the lithium battery can be an early sign. Attention: How long the battery smokes before thermal runaway occurs varies greatly. The time window cannot be precisely estimated. There is always danger in the event of outgassing or smoke.
The internal short circuit within a cell leads to a chain reaction (jump to neighbouring cells within the module, which then heat up themselves and also run through). Once a cell has passed through, it is lost. You can only prevent further cells from passing through by cooling them with an extinguishing agent and thus interrupting the chain reaction.
Lithium batteries can usually be easily extinguished with water due to their cooling effect. DENIOS storage rooms for lithium-ion batteries offer a wide range of equipment for fire fighting, e.g. B. by installing extinguishing systems. In individual cases, however, water may be unsuitable, for example for fire fighting on lithium metal batteries - under no circumstances should water be used for extinguishing. Therefore, there are other means of fire fighting that prevent the fire from spreading. Lithium-ion cabinets from DENIOS are available in model variants with aerosol extinguishing technology. The DENIOS lithium storage rooms are also available with aerosol extinguishing technology. In order to minimise possible fire damage in transport boxes for lithium batteries, a filler made of silicon dioxide (pyrobubbles) is used - it has a low thermal conductivity and has an electrical insulating effect.
The competent authority decides in each individual case whether or not extinguishing water retention is required. If necessary, DENIOS can provide suitable equipment solutions for room systems and liquid barriers.