UK fast tracks e-scooter battery standard to tackle fires

The UK government is fast-tracking development of a new standard for e-bike and e-scooter batteries following a report by the Warwick Manufacturing Group (WMG) at the University of Warwick.

The UK’s Office for Product Safety and Standards (OPSS) commissioned WMG to produce the research to improve Government’s evidence base on the risks associated with unsafe e-bike and e-scooter batteries and chargers, following a rise in the number of fires in the UK related to these products, some of which have sadly led to fatalities.

This research covers the safety of lithium-ion batteries, chargers and conversion kits for e-bike and e-scooters, collectively called personal light electric vehicles (PLEV) and is leading directly to the new standard for better battery packs and battery management systems (BMS).

The OPSS has commissioned the British Standards Institution (BSI) to develop a new Publicly Available Specification (PAS) (fast track standard) to cover the safety of lithium-ion batteries. In the meantime new statutory guidelines setting out the safety mechanisms that lithium-ion batteries for e-bikes must contain to address the risk of thermal runaway.

The research gives new insight into how battery failures in e-scooters and e-bikes occur during real-world use and environments. It highlights the potential shortcomings in technical requirements in product standards that have not kept pace with technological innovation

Teardown of some products has shown examples of poor manufacturing processes and quality, absence of essential safety features such as temperature sensors, and poor design choices that increase the likelihood of water ingress and cell overheating.

The batteries also have widely differing sophistication in the electronic components used in their battery management systems (BMS). In some cases, the hardware restricts the ability for the battery manufacturer to configure the BMS for the operating limits of individual cell types, meaning that inappropriate generic limits are used.

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In WMG’s view, battery safety should not need to be a factor in purchasing decisions. Safety should be inherent to all products offered for sale, irrespective of their price and other attributes, as is required by existing UK legislation.

To achieve this, PLEV batteries must be designed to protect themselves against reasonably foreseeable misuse and manufactured to consistently high quality levels. However, evidence of the growing number of serious PLEV fires in the UK shows that some manufacturers are failing to achieve the level of safety required in UK consumer product legislation.

Product testing has also shown that some PLEV battery management systems fail to respect the current and temperature limits specified for the cells that they use. Both the cells and the BMS protective circuits are susceptible to damage, which can lead to thermal runaway, especially if the battery is used with an incompatible charger.

These susceptibilities can and should be addressed by improved BMS design and testing. Inspection of the general design and manufacturing quality of the tested products has shown examples of other deficiencies, such as lack of waterproofing and poor weld quality, which manufacturers should also address.

Enforcement of legislation and market surveillance may currently be compromised by a lack of consistency in the consumer safety legislation which applies to PLEV products, particularly separately-sold batteries. Further inconsistency and shortcomings in the supporting standards also undermine the need for clarity, uniformity and technical robustness to help manufacturers to comply with legislative requirements.

The research brings together evidence and data from the UK and overseas with input from across the supply chain with detailed technical product inspections and product testing in laboratory settings and makes a large number of suggestions for actions which can improve PLEV safety.

“We are delighted to have had the opportunity to assist OPSS to achieve a deeper understanding of the root causes of these battery fires,” said WMG.

Since 2022, enforcement activities have led to 21 product recalls and 29 Product Safety Reports being published for unsafe or non-compliant e-bikes or e-scooters subject to corrective action. This includes withdrawal notices to remove from sale two dangerous models of Unit Power Pack (UPP) e-bike batteries.

“We have regular regulatory dialogue with senior representatives from major online marketplaces to set out the risks these products can pose and have been clear with these businesses about our expectations of the action they need to take to keep consumers safe,” said the OPSS. “Some have banned certain products entirely. We continue to closely monitor action taken by these businesses to assess whether it is having a positive impact.”

The e-scooter battery report is here