A Calgary man is recovering from severe burns after sparks and flames erupted from the pocket of his pants outside a Beltline restaurant Friday night.

Terrence Johnson and his wife Rachel Rex had enjoyed an evening out at their favourite restaurant, The Embarcadero, with their favourite server. While leaving the restaurant in the 200 block of 17 Avenue Southeast, the couple and Greg, their server, stopped to chat outside the establishment but the friendly conversation was interrupted in dramatic fashion.

“All of a sudden there were flames everywhere,” recalled Rachel. “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 Terrence who initially though his cell phone or electronic-cigarette had exploded.

The pocket explosion turned out to be the result of a spare e-cigarette battery coming into contact with loose coins.

“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 Rachel. “He tried to put it out with his hand and he burned his hand too.”

“Where it was going off it was a direct hit and that’s where the third degree burn took place,” added Terrence. "The rest of it was first to second degree burns.”

Heat from the explosion fused the battery to Terrence's jeans.

Terrence, a plumber and gas fitter, was transported by ambulance to the Foothills Hospital where his wounds were cleaned and dressed, with polyester remnants removed. The injured man was released as a burn unit outpatient but doctors suspect his thigh will require skin grafting.

The married couple says their harrowing ordeal is even more frightening given the thought their children could have been standing next to a battery and coins, or keys, in Terrence's pocket at any given time.

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

Terrence has been using e-cigarettes for several years and says, in all his time in vape shops, he has never been warned of the dangers of the batteries 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.”

Rachel said the idea of an exploding spare battery had never crossed her mind. “There are cases we’ve heard where e-cigarettes, the actual unit with the battery, have blown up in people’s faces but this is the first time us, and everyone we know, has heard of a battery going off.”

The majority of modern e-cigarette batteies are lithium-manganese that, while considered safer than the lithium cobalt batteries of old, produce a significant discharge when shorted out.

The painful burns and the realization that batteries can explode have permanently soured Terrence on smoking. “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.”

Terrence and Rachel add they're appreciative of the efforts of the staff of The Embarcardero post-explosion. The couple says workers attended to Terrence until a paramedic crew arrived, collected fragaments of the e-cigarette battery and charred coins, and provided them with a surveillance camera recording of the explosion.

A Go Fund Me page has been created to help the family with expenses.

With files from CTV's Kevin Green