Camera in Trailer and earth

[Random88]

Hi,
Tested camera in a horse float.
1.Screen to +pos and -neg battery terminals. Did not light up when black wire went to chassis.
2. Camera red wire to +pos battery terminal and it started to transmit.
3. Surprised that even if the black wire of the camera was not connected to anything, the camera still worked!
4. Camera unit is just warmer than body temperature when I was considering leaving it permanently on rather than hooking to reverse or lights circuit.

Question:
Although the camera is working, should I connect the other camera wire to earth or -neg terminal?

Thanks in advance

[slug_burner]

Your battery -ve and the car body are connected together somewhere in the engine bay. Usually some place close to the battery or near the starter. The starter current has to get back to the battery somehow.

Yes if you have a load that is getting hot then the current is likely to drain your battery in a day or two.

[Random88]

Rang a friend who has done some of this before. Said the coax cable is probably earthing the camera but that would be wise to attach it to -neg.

Said he has had a cheap camera overheat and spit the surround off. Not all are rated for continuous use! Only built for the occasional reversing job. Good to know. I have decided to hook it into the Lighting circuit. That way when she wants to see how the horse is traveling she can switch the lights on, doesn't travel much at night anyway.