Yes. Hazard lights can drain the battery of your car. Any electrical device in your vehicle can become a drain if its left on such as headlights, radios, and even door pins. These things can be problematic if they are left operating when your vehicle's motor is off. Meanwhile when your car is running, the alternator powers the electronics. Also, the hazard lights are designed to use minimal power, to buffer the drain on your battery thus, eventually your hazard lights can and will drain your battery completely.