Wiring Reverse Camera on with key powered by battery

[ErrorsBy404]

I'm asking for assistance about how i might be able to make this happen. I'm thinking a relay would do this but i have no idea which relay.

I'm looking to have a constant on rear camera that i can access from my head unit any time while the vehicle is on.

I do not want to use with the wiring behind the dash that connects to the head unit itself.

I have a Add-on Fuse Panel that i want to use which connects direct to battery.

Thanks

 

[telectrix]

what i have done is to take the 12V supply to the camera from the rear screen demister. that way, as long as the demister is on, the camera will work. also doubles as a secondary rear view mirror.

 

[ErrorsBy404]

what i have done is to take the 12V supply to the camera from the rear screen demister. that way, as long as the demister is on, the camera will work. also doubles as a secondary rear view mirror.

my vehicle is not equipped with a rear demister(or defroster). and i wouldn't want to run my defroster every time i drive my vehicle.