FMJ Facilities Management magazine providing industry-specific intelligence to FM and property professionals
By Matt Partridge, Head of Product Development, Armorgard UK
Anyone working on a construction site or facilities floor today knows that lithium-ion batteries are everywhere. They’re powering drills, saws, scanners, access equipment and more. That’s a shift that’s happened fast! For context, Technavio research highlights that cordless tools now account for more than 80 per cent of professional power tool sales in the UK, up from roughly half just eight years ago. The technology has transformed how trades and facilities teams work. The risk profile has changed along with it.
UK fire brigades attended 1,760 lithium-ion battery fires in 2025. That’s a sharp year-on-year and works out at roughly one callout every five hours. The London Fire Brigade has called it the fastest-growing fire risk in the capital. The National Fire Chiefs Council has been blunter still: safety standards, it warns, haven’t kept up with the speed of battery adoption. As summer arrives, that warning speaks directly to the hot weather battery risk on every site.
Why batteries fail
There are three main reasons lithium-ion batteries fail: physical damage, electrical faults and thermal failure. The first two factors are fairly well understood. It’s the third that concerns us most when temperatures climb.
Battery overheating degrades cells slowly and invisibly. Most OEM manuals place the window for safe battery charging at roughly 15-30°C, not unlike the temperature range humans find comfortable. Outside that window, degradation accelerates. Left unchecked, this can trigger thermal runaway: a chain reaction in which the battery generates its own heat faster than it can be released. It is extremely difficult to stop once it starts.
According to the Met Office, Summer 2025 was the UK’s warmest since records began. That was not an outlier event. It has calculated that similarly hot summers like 2025’s are now around 70 times more likely than in a pre-industrial climate. For anyone storing or charging lithium-ion batteries on site, that context matters.
The role of ventilation
Ventilation is a misunderstood element of lithium-ion battery storage. It does two distinct jobs, both are critical.
First, it prevents heat from building up during charging. Chargers and batteries generate heat through the inefficiencies of the charging process. In a poorly ventilated space, that heat accumulates. Combined with ambient summer temperatures, it can push batteries past their safe operating range.
Second, if a cell starts to fail, it produces gases. In a sealed or poorly ventilated storage space, those gases build up, pressurise and create a risk of explosion before a visible fire even starts. Good ventilation allows those gases to escape, representing an essential battery fire safety criterion.
The butterfly effect on site
A battery fire in isolation is serious. A battery fire on a construction site with flammable products such as dry timber framing, combustible dust and insulation materials becomes something far harder to contain.
Lithium-ion fires can burn at over 1,000°C. At that temperature, almost any common material ignites on contact. To address this, ISO 3941:2026, the updated international fire classification standard adopted by BSI this year, has created a new Class L classification specifically for lithium-ion battery fires. Class L recognises that lithium-ion battery fires behave differently from Class A, B or C incidents. They’re harder to extinguish, prone to re-ignition and produce toxic gases that present their own serious risks.
Where you store your batteries matters. Apply the same logic you would use for gas bottles or fuel bowsers, setting segregation as the standard safety best-practice.
Weather isn’t just about heat
Summer brings more than sunshine. The same climate patterns producing record heat are delivering heavier downpours, rapid heat-dry cycles and localised storms. Electricity and moisture are poor partners. Water ingress into charging equipment or damaged battery casings adds another failure pathway that is easy to overlook when the sun is back out.
A commercial argument, too
Beyond safety, there’s another pragmatic reason to get this right. Managing lithium battery temperature extends duty cycle and overall lifespan. Batteries that are repeatedly cycled through heat stress degrade faster, hold less charge and need replacing sooner. Good storage practice protects your assets.
What good looks like
At Armorgard, we test our battery charging units across a wide range of lithium-ion battery types and sizes, varying fire speeds and temperatures. That work has shaped a clear view of what separates the merely adequate from genuinely protective storage. The gap between the two is wider than most people expect.
Don’t wait for a heatwave to review your summer battery storage. Check exactly where and how you’re charging lithium-ion batteries on site. Look for ventilated battery storage, appropriate segregation and solutions tested specifically for lithium-ion battery risks rather than generic Class A fire scenarios.
The standards have moved. It’s time to ensure your storage practices have kept up. Find out more here.
Matt is Head of Product Development at Armorgard, a manufacturer specialising in secure storage, manual handling and site safety solutions. With more than a decade of experience in research and development, Matt has spent much of his career at Armorgard creating practical products that help make work on site safer, simpler and more efficient.
In recent years, Matt has led significant work in the field of lithium-ion battery charging safety, supporting research into safe charging, conditioning and storage practices, as well as the fire risks associated with battery-powered tools and equipment. Through extensive testing, he and his team have provided valuable data and insight to technical committees and industry organisations, helping to inform safer standards and best practice.
Working closely with contractors, fleet operators, tool manufacturers and safety professionals, Matt translates real-world site challenges into product innovation that improves safety, compliance and productivity. He is particularly focused on raising awareness of battery fire risk and helping construction, rail and industrial organisations adopt safer approaches to lithium-ion battery charging and storage.
Matt is passionate about developing user-centred solutions that respond to emerging workplace risks and support safer working environments across the construction and industrial sectors.
