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April 29, 2022

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Lithium battery fires

Are E-scooters and similar devices the new major fire risk?

The Firechief team explains why there are increasing concerns over lithium battery fires from items such as e-scooters, and advises on what to use if an incident were to occur.

Historically, the focus on significant causes of fires and deaths in the domestic environment has shifted between the decades. In the 1970s and 80s, emphasis was on the presence of paraffin heaters, electric blankets and most significantly, foam filled furniture in the home, while in the 1990s it was the lack of smoke alarms for early warning and the 2000s it was white goods, particularly tumble dryers. A number of these well-publicised risk factors have had a key part to play in the development of contemporary fire safety legislation.

e-Scooter-FireLithiumBattery-22

Today, the move towards reducing the impact on the environment whilst retaining mobility has seen a big increase in electrically powered transport, including personal modes of transport such as hoverboards, electric bikes and e-scooters.

However, the widespread adoption of these personal modes of transport has also been accompanied by a worrying increase in fires resulting in substantial property loss, injuries, and several deaths. With an estimated 200,000 scooters already in use in the UK and the number rapidly increasing, the risk of further fire related incidents also escalates.

Transport for London’s ban on private e-scooters, which prevents them from being taken onto the capital’s transport network, came into force at the end of 2021, following an incident in November which saw an e-scooter catch fire on a train stopped at an underground station.

 

This growing issue has been of significant concern with Fire and Rescue Services across the UK for some time. In 2021 firefighters in England attended more than 50 blazes as a result of e-scooters or e-bikes, in comparison to 2020 which saw half that amount for the whole year. This prompted London Fire Brigade to issue an urgent safety warning.

The battery technology is at the heart of the issue with energy-dense Lithium-ion battery packs normally being used in these rechargeable devices.

So why are Lithium batteries a fire risk?

To understand the risk, you need to know a little bit about Lithium batteries. As the name suggests, Lithium-Ion batteries use lithium Ions to generate the power required by our ever-increasing number of devices.

With a single cell Lithium battery, once the cell has released all of its energy, the battery has finished its life. However, the Lithium-Ion batteries used in devices such as mobile phones, laptops, power tools, and electric vehicles (EVs), have a larger number of cells (ranging from two to thousands) and can be recharged many times.

There are three types of cells that may be present within a battery pack – cylindrical, prismatic, and pouch cells. Many cells in a battery make a module and many modules will make a battery dependent on size, from 10 plus cells in small Lithium-Ion batteries to over 7000 cells that are placed within an EV, such as a Tesla.

The benefits of Lithium-ion batteries are that they are small, lightweight, and capable of storing a large amount of energy. However, they are also volatile under stress, making them a fire risk.

What causes Lithium battery fires and what is Thermal Runaway?

The failure of a Lithium battery is usually due to a short circuit or damage from overcharging, overheating, penetration or crushing.

Warning signs that a battery pack or cell is likely to fail include the battery appearing to bulge or swell, sometimes accompanied by other signs such as discharging too fast and/or the battery being hot to the touch.

Once a battery fails or ‘runs away’ the cells usually start to give off smoke. Thermal runaway is the chemical process within the battery which produces heat and flammable toxic chemical gases very quickly, often before any flame appears. These gases include Carbon Monoxide, Carbon Dioxide, Hydrogen Fluoride, Hydrogen Chloride, Sulphur Dioxide and Hydrocarbons such as Ethane, Methane, Butane and Hydrogen Cyanide, none of them something you would choose to be exposed to.

A lithium-based battery burns extremely hot (between 700◦c and 1000◦c) so the temperatures involved, and the sparks generated cause a fire, further fuelled by the vented gases as the battery cells decompose further, resulting in rapid fire spread. This process happens far more quickly than any other types of fire. The reactions, once started, increase so speedily that the cells typically appear to ‘explode.’ Due to the self-sustaining process of thermal runaway, Lithium battery fires are also difficult to quell. Bigger batteries such as those used in Electric Vehicles can reignite hours or even days after the event, even after having been cooled.


What to use on Lithium battery fires?

When dealing with Lithium-Ion battery fires, water-based extinguishers will provide an essential cooling effect, but they are not able to form a thermal barrier around the fire. When you run out of water-based extinguishant, you’ve run out of fire suppressing power. The battery forms its own flammable gases (including oxygen) and heat, and will re-ignite, burning until the cell fully discharges its energy.

Foam is designed to smother with a film on the surface of the fire, but the film will not survive the high temperatures reached in a Li-Ion fire. The same applies to Wet Chemical.

Powder is completely ineffective, as it has no cooling effect, and will not cling to vertical surfaces of the cell.

Firechief Lith-Ex extinguishers have been designed to suppress Lithium battery fires in their infancy before they develop into a fully established fire. They can also be used to protect against fires where batteries are stored or charged. Firechief Lith-Ex extinguishers contain Aqueous Vermiculite Dispersion (AVD), a revolutionary fire extinguishing agent. AVD is made up of Vermiculite particles chemically suspended in water, discharged in a fine mist which provides both a cooling effect and forms a heatproof barrier around the burning battery cell to prevent propagation and re-ignition. Vermiculite has very strong thermal insulation properties and therefore prevents heat transfer from the burning cell to its surroundings. This means the chemical reaction is contained within a thermally stable coating so that external flames can be dealt with by the cooling effect of the water. The Vermiculite film is not electrically conductive and is environmentally friendly.

The Firechief Lithium Battery Safety Range also includes Heavy Duty Lithium Battery Fire Blankets, Fire Suppression Kits and Fire-Resistant Containers which are designed for the safe storage and transit of Lithium batteries and the smaller devices which contain them.

How can you prevent or reduce the impact of an e-Scooter Lithium battery fire?

  • Buy branded electric scooters and their accessories only from reputable sources.
  • Don’t overcharge your e-scooter. Avoid leaving your machine on the socket unattended, and also remember to use the correct charger. Using a generic charger as opposed to the manufacturer’s official charger is not advised.
  • Don’t use batteries that have been punctured, crashed, dropped, or damaged.
  • Avoid leaving your e-scooter in areas with extreme temperatures such as leaving it out in the sun all day long or putting it in the kitchen.
  • Leave a time interval between riding, charging, and riding again. After use, particularly prolonged use, the battery will already be hot – charging it straightaway will heat it further, risking damage. Likewise, after charging a battery will be hot, so immediately using it will also risk overheating.
  • Charge in a safe location. Avoid charging in the house – if you have a garage or outbuilding use this as even if a fire occurs you are more likely to escape, and the damage can be limited. If you can’t do this, then avoid charging overnight and do not charge where a fire would come between you and the exit – for example charging in a hallway could trap (and possibly lead to the death of) everyone in the flat regardless of which room they are in.
  • Take precautions for if a fire occurs:
    • You should have working smoke alarms ideally in every room, but as a minimum in your hallways/landings (note – more stringent regulations apply in Scotland) so you get time to escape. However, bear in mind that lithium battery fires can escalate so quickly that this may not be enough, particularly if you have picked a poor charging location.
    • Consider using flame retardant bags and pouches to store lithium-ion batteries in, ideal for where they are being left unattended.
    • Special fire blankets are available that can quickly be draped over the burning item which will buy valuable time to escape safely and will restrict the spread of fire.
    • Professionals who use and/or store Lithium batteries such scooter hire, sales, and service companies, etc, should consider installing one or more of the Firechief Lith-Ex fire extinguishers designed especially for tackling Lithium-ion battery fires.

For further information about Lithium battery fires and how to manage them, visit the Firechief team on stand FI2224 at FIREX or visit our website Lithium Battery Safety Range – Firechief Global.

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