Tackling the hidden danger of lithium-ion batteries

Lithium battery power has changed the face of construction, with kit everywhere onsite. But with this proliferation comes the increased risk of devastating fire.

Often, there are no warning signs such as smoke, smell or visible swelling. A battery can look fine right up to the moment it isn’t. And then its ferocious flames and toxic vapour defy standard firefighting methods.

Guidance from the Health and Safety Executive, HSG168, Fire Safety in Construction, names lithium-ion batteries as a significant ignition source.

Tools and chargers onsite

Cordless tools, survey kit, lighting and comms all use lithium-ion battery power, potentially creating efficient, calmer work sites with reduced accident rates. Contractors looking to reduce their carbon footprint and meet sustainability targets are also likely to favour lithium-ion batteries.

On a busy site, there might be 40 trades, most subcontracted, many bringing their own tools and chargers. This exposes construction to a scale of potential risk unique to this sector.

“The kit is everywhere; the proper habits around its use are not,” warns Matthew Partridge, head of product development at Armorgard UK.

What happens when they go wrong

Batteries fail for a handful of reasons, such as physical damage and electrical faults. Most people underestimate the risk of thermal failure. Heat wears down cells slowly and invisibly, with most manufacturers putting the safe charging window at 15-30°C. When a battery pushes past that range, the cells degrade faster and it can tip over into thermal runaway where the cell produces heat faster than it can shed it.

Phil Clark, National Fire Chiefs Council, explains: “Once thermal runaway commences, the process generally only ceases when the battery cells have completely ‘burned out’. Because thermal runaway will continue in the absence of oxygen and because it is so difficult to apply cooling to the unaffected cells around the defective ones, normal firefighting tactics are not sufficient.”

As well as jet-like flames at over 1,000° C, the battery is also likely to produce a toxic and explosive vapour cloud at a rate of 300–6000 litres per kWh of battery power.

Impact on insurance

When a lithium-ion fire breaks out on a construction site, it finds plenty of material to work with. They start where the batteries live – next to timber, fuel, packaging and half-built structures.

Insurer Zurich has seen an increase in fires claims through power tool stations being overcharged. It says site offices pose a particular risk where over charged laptops can overheat and ignite. 

As well as having to replace portable cabins, firms have experienced delays and financial loss through site access being impacted or from sub-contractors losing equipment and being unable to work at capacity. There could be contractual penalties and reputational damage if projects cannot be completed on time.

Aviva asks sites to take precautions, such as establishing formal charging arrangements. Its top tips include segregating battery charging within fire resisting compartments. 

Good practice

Simple steps include checking a battery before use and reporting it if it is damaged, swollen, discoloured, hot, hissing or giving off an odd smell. Charge the battery at 15-30°C and never in direct sunlight or in a hot van. Do not leave anything charging unattended or plugged in overnight without someone watching it.

“The difficulty lies in getting a rotating cast of trades to do it every day without being continually told,” says Partridge, advising that all workers need to know who to speak to when a battery appears faulty.

Talk to us

Please contact the Focus team to discuss your battery use and disposal methods. We can provide bespoke guidance and risk management solutions to help reduce the risks of ignition and fire spread.