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FAQ Lithium Batteries

Lithium-ion batteries are everywhere - they supply power for smartphones, computers, cordless screwdrivers, robotic mowers, e-bikes and cars. Lithium batteries 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. In order to limit the fire hazards posed by Li-Io batteries as best as possible and to be optimally prepared in the event of a fire, DENIOS answers the most frequently asked questions about handling lithium batteries here.

Differentiation between battery types

Which lithium batteries are available?

Lithium batteries differ on the one hand in their cell chemistry - there are, for example, lithium polymer and lithium iron phosphate batteries. On the other hand, they differ in their performance (number of cells built into the battery).

Which type of lithium battery burns the most?

Although certain compositions are generally considered safer, no statistics exist regarding cell chemistry that confirm an increased or decreased fire risk of certain battery types. The association of property insurers differentiates in a risk assessment according to performance classes (low, medium and high power). In practical terms, the highest fire risk comes from a defective battery.

What are medium power lithium batteries?

Medium capacity lithium batteries are all lithium metal energy storage devices with > 2g Li and ≤ 12kg gross per energy storage device. For lithium-ion energy storage devices, > 100 Wh and ≤ 12kg gross per energy storage device are specified. Medium-power lithium batteries are installed, for example, in pedelecs, e-bikes, e-scooters or larger gardening tools.

Insurance questions about lithium batteries

Is it necessary to notify the property insurer that equipment powered by lithium batteries is being used?

A so-called increase in risk must usually be reported to the property insurer - i.e. the deviation from the originally insured condition. A good example is the bicycle dealer who previously sold mainly classic bicycles and now has many e-bikes in his range. However, the use of battery-powered devices can also represent an increase in risk in other contexts. In case of doubt, we recommend that you consult with your property insurer to clarify the situation in each individual case and to agree on suitable safety concepts for lithium batteries.

Is it necessary to keep a battery register?

In contrast to registers of hazardous substances, 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 amount of Li-Io batteries present in the company and the resulting hazards. This can provide you with valuable knowledge for your risk assessment, from which you can develop suitable safety measures for lithium batteries.

Storage of lithium batteries

How many lithium batteries can be stored indoors?

So far, there is no legal regulation on the maximum number of lithium batteries that can be stored in buildings. Your property insurer will specify this.

Why not fully charge lithium batteries before storing them?

Lithium-ion batteries should not be fully charged before storage to counteract rapid ageing of the battery. In addition, a lower amount of stored energy can also reduce the severity of the reaction in case of fire.

Does it make sense to tape off the contacts of the lithium battery before storing it?

Yes, this makes sense, as it significantly reduces the risk of short circuits. However, the contacts can only be taped on single cells with open poles. If the contacts are protected by the battery housing, taping is not possible.

How can lithium batteries be optimally stored for a longer period of time?

Lithium-ion batteries should ideally be stored at cool temperatures in lithium storage cabinets or lithium storage rooms. The state of charge of the lithium batteries should be between 30 % and 50 % and should be monitored regularly to prevent deep discharge. From a state of charge of less than 5 %, the respective lithium battery should be recharged to avoid damage due to the natural discharge process. This is individual and depends on various factors: Temperature (higher temperatures favour faster discharge), original state of charge and cell chemistry. In some products, such as robotic mowers, there are special winterisation functions with which the battery management system carries out automatic trickle charging. As a rule, however, a regular manual check is necessary.

How can specifications for separate storage of lithium batteries best be implemented in everyday operations?

The association of property insurers prescribes structural or spatial separation for the storage of lithium batteries, whereby different safety distances apply depending on the power class in the case of spatial separation. Storage or charging cabinets for lithium batteries are an optimal solution in practice, as they are the best and easiest to integrate into production operations from an organisational point of view. With a charging cabinet, defined charging locations are specified where employees place their devices for charging. Otherwise, the employees would always have to ensure that the safety distance required in the individual case is maintained - however, this variant is unsafe because it is difficult to organise and control.

How many batteries can be stored in a lithium-ion cabinet?

There is no standard legal or insurance quantity limit. In practice, the size and design 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, allows storage of lithium batteries with a total weight of 75 kg per storage level. The power requirements of the chargers are also relevant when selecting charging cabinets. In the DENIOS SmartStore charging cabinet, for example, 3 x 16 A are available. If the lithium-ion cabinet has an integrated extinguishing system, the operating instructions will provide information on how much storage space, if any, must be kept free to ensure optimal extinguishing in the event of a fire.

Are there also lithium battery storage cabinets for outdoor use?

For the outdoor storage of smaller quantities of lithium-ion batteries, DENIOS offers the compact RFP 115 Li-Ion fire protection storage system.

Lithium battery charging

Is there a fire hazard only during the charging process?

There is an increased risk of fire when charging lithium-ion batteries. The danger is particularly great when charging a battery with a critical defect or with a defective charger.

Which charger should be used for lithium-ion batteries?

The charger must be compatible with the lithium batteries used and should be considered suitable by the manufacturer of the Li batteries. As a rule, these are the chargers of the manufacturer. The use of counterfeit products is not recommendable.

What should be considered when charging Li-Ion batteries during non-operational times?

The charging of a lithium battery should always be supervised. However, when charging Li-ion batteries during non-operational times, for example at night or at the weekend, staff supervision is not guaranteed. Therefore, for insurance reasons, among others, 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 of critical lithium batteries

How to recognise a defective lithium battery?

Defective lithium batteries pose the greatest danger. However, a defective Li-Io battery is often difficult to detect. Internal defects are not necessarily visible on the outside of the battery. It may be that the charger detects a defect - but you should not rely on this 100%. External signs of defective lithium batteries are, for example, a damaged casing (signs of mechanical damage) or a bloated casing (signs of thermal damage).

How should you deal with a defective lithium battery?

If there is significant external damage to a lithium battery, the battery should be separated immediately and sent for disposal. A quarantine container or a transport box approved for defective or damaged lithium batteries is suitable for this purpose.

What should you do if a battery device falls down?

In practice, it happens from time to time that a unit powered by lithium-ion batteries falls to the ground. The fall can cause mechanical damage - depending on the external circumstances such as the height of the fall, ground conditions or the type of construction of the device (is it a robust quality product or an inferior product?). If a battery device has fallen down, you should first check it visually: Is the casing cracked? Is the device still functional? Does the charger report a problem? Heavily damaged devices should not simply be repaired, e.g. with duct tape, but either professionally inspected and repaired or disposed of.

Extinguishing lithium battery fires

What events lead to the fire hazard from lithium batteries?

The cause of fires in lithium-ion batteries is always a short circuit within a cell, which leads to thermal runaway. Various events can trigger this short circuit, e.g. overcharging by the charger, heating or ingress of foreign bodies.

Can you predict a thermal runaway?

Yes, due to outgassing or smoke coming out of the lithium battery. Caution: How long the battery smokes before thermal runaway occurs varies greatly. The time window cannot be estimated exactly. In case of outgassing or smoke, danger is imminent in any case.

Can you extinguish a burning lithium-ion battery?

The internal short circuit within a cell leads to a chain reaction (jump to neighbouring cells within the module, which heat up and also go through). Once a cell has gone through, it is lost. The only way to prevent further cells from going through is to cool them with extinguishing agent and thus interrupt the chain reaction.

Which extinguishing agents are suitable for burning lithium-ion batteries?

Lithium batteries can usually be extinguished well with water due to the cooling effect. DENIOS storage rooms for lithium-ion batteries offer a diverse range of equipment for firefighting, e.g. by installing extinguishing systems. In individual cases, however, water may be unsuitable, for example for fire-fighting on lithium metal batteries - here, water must never be used for extinguishing. Therefore, there are other means of fire fighting that prevent the spread of fire. DENIOS lithium-ion cabinets are available in model variants with aerosol extinguishing technology. DENIOS lithium storage cabinets are also available with aerosol extinguishing technology. To minimise possible fire damage in transport boxes for lithium batteries, a filling agent made of silicium dioxide (pyrobubbles) is used - it has a low thermal conductivity and has an electrically insulating effect.

Is fire water retention required in the battery store?

Whether fire water retention is required is decided by the responsible authority in each individual case. If necessary, DENIOS offers suitable equipment solutions for room systems and liquid barriers.

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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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