This is probably a pretty basic question but …
I want to add in a 12v cigarette lighter style sockets underneath my main console. This is just to give me flexibility between 12 volt devices plugged in directly, and 5 volt USB devices like phones and sat navs that can be powered though one of those little plugs with USB sockets on.
The location is right next to my main fuse box so I want to connect in to it using a piggyback fuse holder as it’s close and convenient and I can do it with a short run of cable and no cutting.
The lighter socket has a red + wire and the black - wire coming out of the back.
Previously when I’ve connected devices to my main fuse box they’ve been really low powered. Usually no more than 2 amps, and they’ve come with a stepdown converted from 12 volts to 5 volts. Dashcam hardwire kits and things like that.
I’ve connected the + wire to the tail on the piggyback fuse holder, and put in a low rated fuse, and then connected the - wire to a bolt attached to my chassis. The instructions on my last dashcam hardwire kit said that this was how I should be doing it.
I presumed that this is what I would need to do with the 12v cigarette lighter socket, but the instructions say to connect the - wire to the - terminal on the battery, and the videos that I’ve been watching online have all shown the - wire going to the battery as well.
Is this just because the videos were using a battery on a desk as a demonstration, or is this something different that needs to be done with 12V cigarette lighter sockets?
I can easily ground the - to my chassis, but connecting it to my battery is going to be really difficult as there is no easy way to get a cable through the insulation and fireproofing to my battery compartment.
Is it possible\safe for me to ground to my chassis?
I’m not planning on using any device higher than 5 amps, either 12v or 5v