A regulator in the UK has issued a safety warning over a Tesla battery system which “presents a risk of fire”.

The US carmaker, founded by Elon Musk, has launched a replacement programme for affected units of its Powerwall 2 batteries, which are used mainly in homes.

Customers are asked to ensure their system remains online and check the Tesla app for a notification confirming whether their unit is affected, according to the Office for Product Safety and Standards (OPSS).

“The product presents a risk of fire as certain battery cells within affected units may develop internal defects over time,” the UK regulator said.

“An investigation identified that battery cells manufactured by a third party may contain excessive lithium plating, which can lead to cracking of the cell casing.

“This may result in an internal short circuit and subsequent thermal runaway, increasing the risk of the battery overheating and catching fire.”

Thermal runaway occurs when a battery generates more heat than it can safely release, causing its temperature to rise rapidly and uncontrollably.

“The product does not meet the requirements of the Electrical Equipment (Safety) Regulations 2016,” the OPSS added.

Tesla has remotely discharged most affected units and any remaining ones are in the process of being discharged.

Customers should contact their original installer to schedule replacements or contact the support team at Tesla.

Affected units will be replaced free of charge.

Powerwall batteries store energy generated by solar or from the grid, which can be used to power devices and appliances, even during outages, according to the Tesla website. – PA