It’s time to act on Lithium-ion battery safety in micromobility

While lithium-ion battery fires in electric cars seem to attract more attention, the same occurrence in e-bikes ands scooters presents a much more insidious danger, given that they frequently occur in residential properties.

 Electrical Safety First (ESF) have now published a report titled ‘Battery Breakdown – Why are e-scooter and e-bike batteries exploding in people’s homes and what can be done about it?’

The ESF report begins by pointing out that four people in the UK have died this year from battery fires and the London Fire Brigade (LFB) describes lithium-ion battery fires as the capital’s fastest growing fire risk. 

The cause of most such fires is known as ‘thermal runaway’ which is explained: ‘The process starts when a battery cell overheats, perhaps due to an internal fault, physical or electrical abuse, or extreme temperatures. This elevated cell temperature results in exothermic reactions, which produce more heat than can be dissipated to surroundings. Eventually the internal structure of the cell begins to become unstable and collapse, resulting in the venting of flammable and toxic gases, fire and explosion. The heat spreads to nearby cells, causing them also to enter an uncontrollable and irreversible state of thermal runaway.’

Days before the report was pubished, a forum was taking place in the USA focused on e-bikes and lithium-ion batteries. Alexander Hoehn-Saric, Chair of the U.S. Consumer Product Safety Commission, chose the event to call on Congress to strengthen the commission’s authority so it can ‘move rapidly toward establishing mandatory standards’ adding that ‘voluntary standards are not enough.’

As New York City Fire Commissioner Laura Kavanagh was saying in Maryland: ‘These aren’t typical fires. The batteries don’t smolder, they explode.’

As the number of e-bikes and scooters increases, the dangers become greater. New York is home to 65,000 e-bikes and has seen 100 battery fires so far this year, resulting in 13 deaths – compared to just six in the whole of 2022.

There are a number of reasons that batteries go wrong but mistreatment is a significant factor. In this context mistreatment could include DIY conversion of a machine to increase speed or the use of cheap ‘universal’ battery chargers which can charge at higher voltages than intended. ESF found almost 60 listings of substandard chargers for sale through third-party sellers. Simple physical damage, such as regularly hitting the kerb can also be a factor. 

Amongst the report’s recommendations is a change of design that would offer the battery greater protection against both physical damage and water ingress.

In terms of shared micromobility schemes run by local authorities in partnership with private operators, there already a number of regulations in place to which the operators must conform – such as the aforementioned battery location – but ESF say these ‘are generic and lack specifics’.

They also add: ‘The DfT’s minimum technical requirements should include a fire safety risk assessment that considers all aspects of battery charging, storage, use and foreseeable abuse conditions.’

E-scooter and e-bike storage in the shared schemes also causes some concern, leaving the equipment vulnerable to malicious damage.

Other recommendations cover consumer education, a ban on the sale of universal chargers for e-micromobility (or the introduction of standards for non-proprietary charging systems) and the establishment of consistent charging protocols for e-micromobility products to be adopted by industry.

The full report, with all the recommendations can be found here.