What are all of these battery connections on my 17k

[ElkMeadowsFun]

We bought a 2016 Nash 17K equipped with what we believe is a factory installed Cummins-Onan generator. The main control panel in the trailer has an ON switch for it, everything points to a factory install. The trailer also has 2 solar panels, one small and one larger. The 12V batteries on this trailer need to be replaced, we are curious about the number of unspecified leads to the terminals. On the positive side there is a large red cable, looks like 4 ga, we assume this is main power. Then there are 2 of what look like red 8 ga wires, one of these is the parallel connection to the other battery. We don’t know what the second one is. Lastly there is a slightly smaller red wire, maybe 10 ga, with an inline quick disconnect and 30A car type fuse spliced into it. We would really like to know about these last two – what they are and how to test for verification. We have not been able to find any schematics for this trailer. Our plan is to install a battery cutoff switch, use it as a terminal block to make these connections, label them, then wire a pair of golf cart batteries in series between the output terminals of the cutoff switch. We did this on our 2003 Arctic Fox and had good luck with it, batteries lasted much longer than the 12V marine type. Let us know what you know please.

https://photos.app.goo.gl/X3954EiXRfgeU4pH7

[CA_Traveler]

Messed up wiring. 4 ga red wire and then 8-10 ga white jumper and red jumper and smaller black negative wire - inconsistent. Yes disconnect wires to determine usage or buy, borrow or steal (not really) a clampon ammeter which will be useful for the rest of your RV career.

[enblethen]

Posted photo shows something I would correct. Negative wires should be marked with black tape along with jumper.
Blue wires are normally for the electric brakes but I see if changes color at splice. Electric jack?
Looks about like I posted for functions! Only way to really tell is to disconnect each one to see what dies. Solar panel controller would show battery disconnected.

[Boon_Docker]

Here you go my friend.

[ElkMeadowsFun]

Thanks. I'm trying desperately to post a photo but failing miserably. What hosting site are people using these days. Most of the ones in the instructions are no longer in service.

[enblethen]

30-amp fuse could be for the electric tongue jack.
Number 4-gauge wire should be power to the 12-volt distribution panel.
Should be a number 10 wire going to the umbilical cord to tow vehicle.
Number 8 wire could be for the solar panel controller.
Sould be another small wire 10-12 for the break-away switch.
Battery disconnect should not disconnect break-away switch!