The Power Within (1979)

A young man (Art Hindle) suffers a lightning strike on a dark and stormy night. Instead of dying, he absorbs the lightning's electrical energy into his body, losing consciousness. He awakens in a hospital, only to learn that the accident changed both his body and his life, as he knew it, forever. Now he can discharge electricity from his body at will. The government coerces the young man into becoming an operative, and his handler gives him a wristwatch that is not really a wristwatch, but rather is a device that allows him to control precisely his electrical discharges. The hook is that now that the lightning strike "charged" his body, he has no choice but to re-charge the electrical energy stored in his body on a regular basis, or he will die.