“Lithium-ion batteries sold as part of so-called e-bike conversion kits tend to be of a significantly inferior quality and construction when compared to the battery packs manufactured and installed in purpose-built e-bikes”, Mr Potter wrote in his report.
“Lithium-ion batteries sold as part of e-bike conversion kits are regularly sold/supplied without a charger, thereby increasing the risk of an unsuitable charger being purchased and used.
“Chargers for sale on online marketplaces, in particular, regularly fail to meet appropriate standards. In this case, the charger purported to carry the European ‘CE’ mark, which should be an indication that the product conforms to European health, safety and environmental protection standards; however, the Fire Investigation Officer noted that the mark was slightly different and therefore not genuine. It was used instead to denote ‘Chinese Export’.
“The presence of universal charging connectors across batteries of different voltages means that there is a significant risk that over-rated chargers can be inadvertently connected to lower power batteries, which was the case in the fire that led to Mr Lee’s death.
“There is currently no British or European (e.g. BSI or PAS) standard specific to e-bike conversion kits and/or chargers and consequently it is relatively easy for people to buy, particularly from online marketplaces, e-bike conversion kits and/or lithium-ion batteries that are not of sufficient quality or otherwise not of an appropriate standard to charge safely.
“There is an increased risk of people mixing and matching lithium-ion batteries with chargers that carry a different voltage rating.
“When a lithium-ion battery is charged using a charger with a different voltage rating, this can lead to thermal runaway and catastrophic failure of the battery – a build-up of heat, failure of one of the cells within the battery, followed by a chain reaction as the remaining cells fail, all of which can happen very quickly and explosively with the emission of sparks and toxic, flammable vapours.”