GM offers Volt drivers battery upgrade
Safety concerns spark power cell patch plan
General Motors has offered owners of its Volt e-car a free optional battery pack resilience upgrade in a bid to calm fears heightened after one of its cars caught fire after a crash.
GM said the upgrade is intended to reduce the risk of an impact-induced coolant leak - the cause of last year's fire.
In May 2011, the US National Highway Traffic Safety Administration tested the Volt for its impact resilience. Some months later, the test vehicle caught fire . An investigation revealed the blaze was sparked by a coolant leak from the battery.
The agency formally launched a more detailed safety defect probe  in November, with GM's co-operation.
The NHTSA has said it knows of no instances of Volt crashes that have resulted in battery fires, and neither have prangs involving other e-cars fitted with li-ion batteries.
GM will contact Volt owners shortly to offer them the fix, which will be optional.
The Volt has yet to debut in the UK, where it will go on sale as the Vauxhall Ampera . ®