Negative and ground wire questions

The steel frame has less resistance then a #4 wire. Connect with short piece.
Verify that the bolts connecting to frame is at least 5/16, 3/8 would be better. Clean from to bare metal and use de=oxidation compound. Do same at battery connection to frame.

Thank you for the input enblethen. That is the answer I suspected and hoped for.

Run a new, larger negative wire from the converter to the battery.

Do both. Technically there should be only 1 frame connection, but I've had no problem running a new negative battery to converter wire when the trailer already has 2 frame connections for negative return. I'm concerned about corrosion at frame which is often out in the weather.

Wire to the frame is enough. Running a separate wire to the battery is belt and suspenders. Won't hurt anything though. (The wire from the converter to the battery will have more voltage drop than the wire from the frame to the converter. Using both reduces voltage drop even more.)

I'll bring up something to consider.

How long are you planning on keeping the camper?

Do they use salt on the roads in your area in winter?

Is the camper stored outside uncovered most or all of the time?

I restore older campers, mainly the 10 to 20-year-olds range. All of them were not stored inside or had minimal cover when outside. You can learn a lot from an older camper on how things fail.

Frame ground is bad news as a wire conductor as the camper ages when exposed to the elements. The DOT lights use frame ground, the brakes are often set up from the factory using frame ground, the LP pipe, and, yes, battery negative needs to go to frame ground. Corrosion is alive and well in an older camper when stored outside. Aluminum or copper connectors on the wire to the frame are also exposed. This frame ground setup works as a DC conductor when the camper is new. As the camper ages, the corrosion will start making issues.

During a camper restore, I added a DC negative wire to the brakes and the DOT lights to eliminate the frame ground, as the wire connection terminals and the rusted metal connections were all bad. The camper brands I have worked on had the power converter already set up with DC negative with a wire directly to the converter. The weak link, though, was the exposed aluminum terminal block which joined all the DC ground wires at the frame by the battery. That area also gets corrected.

The suggestion is to run your upgraded heavy wire on the DC negative to the power converter if you want to keep the camper for a long time where corrosion conditions exist, as I asked about above.

Hope this helps

John

If you use the chassis as a conductor, you have 4 connections, two at each end. If you use #4 wire, you have 2 connections. Reliability in electricity is a function of the number of connections. 2 is twice as reliable as 4.

If you decide to use the chassis anyway, be certain to use a corrosion limiter such as De-Ox, or similar. Once the connection to the chassis gets rusty, you are in line to have the next problem.