Lithium-ion battery safety advice
9 January 2023
Following the serious fire caused by a self-igniting lithium-ion cordless tool battery at Alide Hire Service’s Bristol depot warehouse on Boxing Day, many hirers have been looking for guidance on measures they can take to prevent such events and mitigate damage.
Because the battery itself and other cordless equipment was destroyed in the fire at Alide’s premises, investigators say it is impossible to know exactly why it ignited. But as the original report on the blog stated, no batteries were being charged at the time.
Following a similar incident two years ago, the HAE produced a guidance document, Hire Industry Safety Guidance for Lithium-Ion Batteries, available for members and published in November 2021. This followed discussions that the association’s Technical, Health & Safety Committee had with manufacturers, suppliers, hirers, battery experts and safety professionals.
Given the diversity of equipment that uses lithium-ion batteries, from survey equipment and cordless tools, to electric mini excavators and compact access machines, the aim was to produce guidance that was proportionate to the risk – which is statistically very small given the sheer number of such batteries in daily use – and also reasonably practicable for tool hire companies to implement.
“The risk of thermal runaway [a domino effect where the intense heat from an ignited faulty cell rapidly spreads to adjacent ones exponentially] is rare,” Carl Bartlett, HAE’s director of certification services told me. He also, incidentally, used to be general manager of Lord Hire Centres, now part of One Stop Hire.
“Manufacturers are incorporating advanced technology in batteries that can identify cell failure or defects. Chargers or testers can often indicate when a battery can’t hold sufficient charge or needs to be replaced. Batteries also contain protective devices within them.
“The monitoring systems for some batteries are so sophisticated that, if there is a problem with the battery, the technology can isolate a defective cell so that it cannot create a thermal runaway event.”
The HAE guidance does not make specific recommendations because of the diverse nature of equipment covered. Also, every hire depot’s circumstances will vary. In addition, some will also have more batteries to manage than others. It’s more a case of taking the most appropriate and practical measures for the particular risks identified.
The document gives an overview and guidance on cordless equipment lithium-ion batteries and general handling advice. It also discusses charging procedures, managing damaged or defective batteries, preventing and tackling fires, storage and transportation, and battery maintenance.
A dedicated section deals with the battery packs utilised in larger plant and equipment.
Another section that I found particularly informative relates to discharged or defective batteries. The guidance states that if a battery has been fully discharged during use and it is then placed into storage without being recharged, the battery could drop below its acceptable limit, damaging the cell chemistry.
“Recharging a battery in this condition may also cause a thermal runaway event,” it states. “Therefore, batteries returned at 0 per cent, or low state of charge, should be charged before storage, and where a battery has been in storage for a long period, the voltage should be checked before it is placed onto the charger.”
A designated and segregated, suitably ventilated charging area where batteries can be left on charge should be determined by both a general risk assessment and fire risk assessment.
Control measures and mitigation procedures may include “non-conductive, fire-proof and chemically resistant shelving or benching, fire detection and provision of suitable fire extinguishers, suitable Li-ion fire blankets or fire suppression system/trace system. If the area is enclosed, ventilation and removal of battery fumes needs to be considered. It may be worth considering containment of waste-water run-off from extinguishers or sprinklers, which may be considered as hazardous waste.”
The guidance also suggests that batteries are stored away from fuel sources such as combustible materials, wooden benches/storage equipment, cardboard, fuels, oils and gases. And if possible, they should be kept in an area away from the main building where, in the event of a fire, this would not affect the wider premises.
● Given the interest in this topic, a number of future blog posts will focus on products developed to prevent or mitigate lithium-ion battery fire damage.
