Ellie Petty was travelling in the fast lane of the A303 near Andover when the vape battery burst into flames.
The 32-year-old stopped her car in the middle of the road and threw off her jacket, before going to the hard shoulder to call an ambulance.
She said: ‘The batteries exploded like a gas torch, I could feel the flames on my side.
‘I stopped the car and left the jacket on the central reservation.’
Ellie suffered third-degree burns to her thigh, with more injuries to her hands, fingers and wrists.
She said: ‘The burns did look quite gruesome. It’s like something out of a horror film.’
She has spoken out about the incident, which happened on May 4, to warn others about the danger of loose batteries.
The Salisbury resident said: ‘It wasn’t advised on the batteries that this was a risk.
‘I just want to make sure that people know that they should never be left loose.
‘They should be kept in a case, rather than left on their own in a drawer at home.’
Hampshire Fire and Rescue said it had been called out after passers-by spotted the flaming jacket on the central reservation.
A spokesman urged people to buy electrical goods from reputable sellers and to make sure they use the correct charger.