Most e-bike batteries will never give you a moment’s trouble. A small number are genuinely dangerous — and because they’re often the cheapest ones online, they end up in a lot of hallways.
Here’s what the government has actually done about it, and what it means when you’re shopping.
The scale of the problem
The numbers come straight from the Office for Product Safety and Standards. In its statutory guidelines on lithium-ion battery safety for e-bikes (summarised by OPSS here), OPSS records that at least 10 fatalities occurred in fires started in e-bikes or e-scooters powered by lithium-ion batteries in the UK during 2023, with almost 200 fires recorded.
That’s a small fraction of the millions of rides taken safely every year. It’s also ten people who didn’t come home.
What actually goes wrong: thermal runaway
The failure mode has a name, and it’s a good one.
Thermal runaway happens when a single cell overheats past a critical point. That cell releases heat, which pushes neighbouring cells over the same edge, which releases more heat. The reaction feeds itself and generates flammable gases very quickly. It’s not a normal fire you can pat out — it’s fast, hot and hard to stop.
A well-designed battery management system can halt the chain at the first failed cell. A cheap pack often has no meaningful protection at all.
What the government now requires
In December 2024, OPSS published statutory guidelines setting out the safety mechanisms lithium-ion batteries for e-bikes must contain to address thermal runaway. Crucially, these apply to batteries sold online and to those supplied with or as part of conversion kits — the exact grey-market corner where the worst products live.
The legal backbone is the General Product Safety Regulations 2005. Placing an unsafe lithium-ion battery on the market is an offence, and OPSS has powers to enforce, including criminal sanctions.
The regulator has used them. OPSS’s regulatory activity update sets out its wider programme, including commissioning the British Standards Institution to develop a new fast-track standard covering lithium-ion battery safety.
There’s more coming. The Product Regulation and Metrology Act 2025 gave ministers powers to update product safety rules through secondary legislation, and in 2026 the government ran consultations on a new product safety framework to replace the 2005 regulations — with unsafe battery fires named as a driver for reform.
Buying and charging sensibly
The government’s consumer campaign is called Buy Safe, Be Safe, and the practical version looks like this:
- Buy the battery and charger the manufacturer made for your bike. Mismatched chargers are a recurring theme in fire investigations.
- Be wary of very cheap third-party packs on marketplaces, especially with no named manufacturer or no compliance information.
- Don’t charge overnight or while you’re out. Charge where you’d notice a problem.
- Never charge in a hallway or doorway. That’s your escape route.
- Stop using a battery that’s been dropped hard, punctured, swollen or soaked. Damage inside a cell doesn’t announce itself.
- Keep conversion kits reputable. They’re in scope of the guidelines for a reason.
The takeaway
Buy from a real brand, use the right charger, charge somewhere you can see it, and retire damaged packs. That covers the overwhelming majority of the risk — and it costs nothing. You can also use precautions like cases for added safety.
Sources: GOV.UK — Statutory guidelines on lithium-ion battery safety for e-bikes (OPSS, 12 December 2024) · GOV.UK — OPSS regulatory activity update: e-bikes, e-scooters and lithium-ion batteries · GOV.UK — Refining the law to better protect consumers