Once u have it wired in properly, it will charge the camera while your car is running. Once you turn your car off your camera will go into parking mode, which is basically a mix of your car battery and the cameras built in battery. Once your car battery drops to a certain level, the parking cable stops charging the device. That way it doesn’t kill your car battery. You can set the drop voltage level to the point you want it by opening the device and setting the jumper. This is a must have for a dash camera. Mine has already caught 2 hit and runs in parking mode in the last 4 months. And since you have a video, it will cut your insurance processing down to one day.