Stumped. Where does this 8gauge white negative dc wire from the board go?

[Toph1170]

I am in the process of replacing the old magnatech 7300 distribution panel with a new one, and will also be replacing the skinny, 20’ long positive and negative 8 gauge wires with thicker gauge.

My question is, where does this (see picture) 8 gauge white negative wire go/tie in to? It’s supposed to go to coach battery negative, but there was no equivalent size wires in the battery compartment, nor connected to the lvd, nor running behind the pillars nor in the loom of wires behind the overhead compartment.

I am concerned that if I abandon it I might be leaving multiple paths open. Any help is greatly appreciated!
Christopher

[Roly]

Does it go to chassis ground? Look under the chassis, in the area where the LVD would be above in the cabin. There are several such ground connections that would be good to renew for good conductance. I have not been under there for a longtime, but remember it that way.

Good Luck, Roly

[noluck]

left frame rail at the back of the coach, you will find 3 or so ground clamps attached to the frame

[Toph1170]

Thank you both for the quick response!
So my questions are:
1-If I am replacing the positive with 4 awg can I just use the existing 8awg white wire? If not (as it is recommended to have pos/neg same gauge), then
2-is it ok to abandon the existing and replace with 4 gauge or will that cause problems?
3-so its ok to connect negative to chassis and not negative battery terminal?

Guess I didn’t know as much as I thought.
Christopher

[deppstein]

When I did my recent battery/charger electrical upgrade, I ran a new 6 awg from battery directly to the distribution panel and left the white negative “as is.” Following guidance from my Forum Mates, I did two things to provide proper grounding in my new setup:
1—ran new 4awg negative from start battery to battery (through the new Orion XS charger, and
2—ran new solid chassis ground from battery (via Blue Sea distribution Safety Hub).
I’ve been testing the new system out for almost a month now with no issues.
David

[BobW9]

1-If I am replacing the positive with 4 awg can I just use the existing 8awg white wire? If not (as it is recommended to have pos/neg same gauge), then

- My original wire was a 6 AWG, as that is what it really should be for the max 45 Amp charger/converter.
- The Positive and Negative don't have to be the same size, though they usually are.
- What is required is that the smallest wire being used at any point has capacity to handle the max current possible, and preferably handle it with no more than a 3% drop over the length (pos+neg) of wiring, battery to charger/panel and back.

2-is it ok to abandon the existing and replace with 4 gauge or will that cause problems?

- The existing white wire (6 AWG for me, and specified by the original 45 Amp Charger/Converter and Distribution Panel as below for Lug C and D in lower right corner), can be left. It goes to the frame as a return path to the battery, but that return path is no longer required when you have another wire going direct to the battery.
- Note all the DC stuff (lights, fridge, furnace fan) are getting positive wires from the distribution panel and using a return negative path via the frame. That seems to be the standard for RV's, which is probably why the dist panel was using a frame return path, too.
- Note that the frame is a large piece of metal, much larger than the wires, so it has much less voltage loss over the distance. When I added some new USB and DC outlets in the overhead compartments, I added new pos and neg wires to the dist panel, as it was easier laying sets of 2 wires in the same place, than having one go to the panel and the neg going to the frame. But because of this, I did use larger wires because that return path over the wire has more voltage loss than a return path over the frame.
- I moved and rewired my batteries when switching to Lithium, putting in direct neg to the batteries, leaving that same 6 AWG to frame leftover.
- Then when I added my Inverter, besides needing a positive and negative to the batteries, it also requires a wire to the frame from its chassis (using that to bond AC neutral to ground when inverting, the frame being AC ground when not connected to shore). I reused that original 6 AWG wire to the frame that was left over. It is probably a bit too small, given the size of the inverter to battery wires, but would normally not be used, and also I almost never come close to the capacity of my inverter.

3-so its ok to connect negative to chassis and not negative battery terminal?

- Yes, as discussed above, it is just the standard in RV's to have a wire from battery to dist panel, and a return negative through the frame. Probably to get lower voltage loss.
- On the other hand, returning directly to the battery is also fine - so long as the battery does still have its own wire directly to the frame. That is required for the return path of all the DC appliances/loads.

[Toph1170]

I didn’t see I had new responses until just now. David and Bob, thank you both for taking the time to answer my questions. I did crawl under the rig and found the return ground attached to the frame (thanks Roly and Noluck for the heads up). So I plan to keep the return (white) attached to the new distribution panel and run new 4awg from panel to as yet installed blue sea safety hub. Hub will have a 2 ga ground to frame, as well as a 4 ga pos + neg to battery.
Thanks again everyone! Christopher