So when it powers off, it goes into a sleep mode. That sleep mode doesn't require alot of power, but if you have it set to turn on if the camera detects vibrations, it uses the cars battery. Mine is plugged in all the time and it only powers on when I turn the car on or it feels vibrations. With the vibration setting, it will turn on when I open my car door. But if your power source isn't powered when the car shuts off, then it doesn't use any power, just what the camera has stored up. Hope that helps 

You need to tap into the reverse lights power harness with the red wire 

Sí, asi es...trae el cable para esa otra camara 

Hi good day, you need to tap into the power line of your reverse light wiring harness