A Calgary man felt sparks and plenty of heat on a Friday night date with his wife after a spare battery for his e-cigarette erupted inside his pants as they stood in front of their favourite restaurant.

Security video from a popular surf and turf joint captured the dramatic explosion. The heat was so intense that Terrence Johnson will require a skin graft to treat the third-degree burn on his thigh. He also suffered first- and second-degree burns on his hands while frantically trying to pat out the flames.

“All of a sudden there were flames everywhere,” his wife Rachel Rex told CTV Calgary. “I actually thought someone had thrown a Molotov cocktail at us.”

“It was almost as if a flare had gone off in my pocket,” said Johnson who initially thought his cell phone had exploded.

Johnson believes loose change inside his pocket reacted with the battery, triggering the explosion.

“It burned through his jeans and he had polyester boxer-briefs on so it melted the polyester to his skin and then it dripped down his leg further,” said Rex.

The heat was so intense that the battery was fused to the burned pair of jeans.

Restaurant staff came to Johnson’s aid before he was rushed to hospital, where staff cleaned the wounds and removed bits of charred underwear from his leg before dressing the area with bandages.

The professional plumber and gas fitter is recovering at home, unable to return to work because of his injuries. A GoFundMe campaign has been set up to help the family with expenses during Johnson’s medical leave.

The couple says they feel fortunate the explosion did not happen near their children.

“If one of our kids had been beside him, they could have been disfigured,” said Rex. “It’s so scary.”

Explosions and serious injuries caused by the lithium-ion batteries that power e-cigarette devices are well documented.

“There can be quite serious cosmetic or functional implications . . . potentially the rest of their lives,” Toronto-area emergency room physician Dr. Brett Belchetz told CTV News last year regarding a rash of e-cigarette injuries.

Johnson said he has been using e-cigarettes for several years and has never been warned of the dangers when he buys supplies in vape shops, or encountered a warning on the packaging.

“I was unaware that a battery could just basically explode and turn into a flare or a torch in your pocket,” he said.

The painful burns and newfound safety concerns have convinced Johnson to kick the habit.

“The e-cigarette did its job, and I was able to quit tobacco cigarettes, but this is scary enough that I will not touch another e-cigarette.”

With a report from CTV Calgary’s Kevin Green