Dash cam installation in Campsie

A dash cam that runs off the cigarette lighter is a compromise from the first day. The lead drapes down the windscreen, the socket is gone, and the camera goes dark when the key comes out, so it sees nothing of the car park.

A hardwired camera takes its power from the fuse box through a proper fuse tap with its own inline fuse. The cable runs up the A-pillar, behind the headlining and down to the camera, tucked behind trim the whole way. When it is done right you see the camera and nothing else.

Pillar trim is not just clipped on. On a modern car it is part of the curtain airbag’s path, and it has to be released the right way and reseated properly. That is careful trim work we do constantly on detailing jobs, and it is the part a rushed installer gets wrong.

And parking mode, the feature most people buy the camera for, only exists with a hardwire. The camera has to see a permanent live circuit to watch the car with the ignition off.

A front camera covers the collisions you are most likely to be blamed for. A rear camera covers the ones you are most likely to be hit by, and rear-end impacts are the most common claim of all.

Rear installations are more work, because the cable has to run the length of the car through the headlining, down the rear pillar and often across a tailgate loom on a hatch or wagon. Done badly it rattles or chafes. Done properly you never see it.

If you park on the street, the rear camera earns its keep in parking mode as much as on the road.

This is the single most common failure we see. Cheaper dash cams use a lithium battery to keep the clock and shut down cleanly. A car parked in a Sydney summer reaches temperatures that degrade those batteries quickly, and a swollen battery is both a dead camera and a genuine hazard.

A capacitor-based camera handles heat far better and is the sensible choice in this climate, particularly for a car that lives outdoors or does parking mode.

It is worth knowing before you buy, because it is not something an installation can fix afterwards.

European, prestige and recent vehicles need more care, not less. Fuse boxes are buried, trim is tighter and less forgiving, and the electrical architecture is less tolerant of a fuse tap installed in the wrong circuit.

Electric vehicles are different again. The 12 volt system behaves differently from a combustion car and parking mode needs setting up with that in mind.

If your car is late model, prestige or electric, say so when you book. It changes how long the job takes and occasionally changes what we recommend.

A rear camera looks through the rear window, and if that window carries a dark tint the camera struggles at night. The picture goes grainy and plates get harder to read.

If we are tinting the car at the same time, we can leave a small clear window in the film where the rear camera sits, which is standard practice and invisible from outside. On a car that is already tinted, a rear camera that mounts on the outside of the tailgate avoids the glass entirely.

Factory privacy glass is lighter than it looks and most rear cameras cope with it. It is aftermarket film in a dark shade that causes the trouble, so tell us what is on the glass when you book.