Adding 12v and USB outlets - newbie wiring questions/paranoia

[ThunderRoad]

I am hoping to add a pair of 12v outlets and a USB Charging outlet to my aframe and I'm having some difficulty wrapping my head around some elements of the wiring. I'm not a wiz on wiring by any means, which may mean I'm overly paranoid if not in over my head and should get it done professionally instead. It's also possible I am totally overthinking all of this and getting paralysis-by-analysis.

Attached is a (crappy) simple wiring diagram I worked up of what I think I should do. Two 10ga runs with all-weather fuse harnesses by the battery, and then tap in the USB outlet (the USB and one 12v will be mounted next to each other, the other 12v is on the other side of the camper).

However, where I get confused is I see references to the return path connecting to the frame and not to the battery, for example. Or that I shouldn't connect too many things to the battery, or put in a fuse panel.

Mostly, I just want power to run/recharge a laptop and recharge things like my phone or a tablet. This is as much a practical endeavor as it is getting a little bit of learning/comfort, as next spring I want to put in a solar panel.

[LadyWindrider]

For starters, 10 ga wire is overkill. 12 ga will run the outlet with the 20 amp fuse. 14 ga will run the other, with the 7.5 amp fuse. As for attaching to the frame, the battery negative is attached to the frame, so in effect, you are using the frame to conduct electricity, rather that running a wire all the way back to the battery, and having too many connections on it.

[ThunderRoad]

Gotcha on the negative-to-frame idea. Makes sense I guess

Is 12 ga wire ok for that 25a run as well?

[LadyWindrider]

You said 25 amp run, and no way are you going to pull that. Most cigarette lighter sockets are only good for 20 amps, using a lighter, less with a plug in charger, more like 10 or so. The usb is only good for 1 amp or less, very small wires. I don't advocate running a small wire, but don't get too big either, especially the price of copper wire.

While you are looking at the schematic, the physical doesn't have to match. Run a 12 gauge down the center of the trailer, to a point, turn it for the dedicated 12 volt outlet. At the turn, tap it for the other outlet and USB port with a 14 gauge. Put a 20 amp fuse at the battery, for the whole ting. Fuse the USB with about 1~2 amp, and you're good to go.

[ThunderRoad]

So I think you're saying something like this?