A home insurance firm is warning people of the hidden fire threat of lithium-ion batteries, as a new survey by NFU Mutual reveals eight in ten people are charging, storing or repairing their devices in a way which greatly increases fire risk.

Lithium-ion batteries are found in almost every household in the UK, in common items such as mobile phones, e-cigarettes and cordless power tools. Larger types of lithium-ion batteries are found in e-scooters, bikes and electric vehicles.

These batteries are capable of catastrophic failure, entering a self-heating cycle – or thermal runaway – that generally results in a fire which spreads as the battery expels its material. These fires burn hotter, for longer and are more ferocious than other types of fire.

To understand the risk faced by UK households, home insurer NFU Mutual commissioned Yonder to conduct a poll of over 1,000 people across the UK. Certain actions can cause devices to overheat or batteries to degrade, increasing the likelihood of fire, and the survey asked whether respondents had done any of these.

Shockingly, it found that 80% of people had done at least one thing to leave their device at higher risk of fire. Well over half (57%) had left a device charging overnight and 35% when they were out, with 30% charging devices on soft furnishings like sofas or bedspreads.