What are all of these battery connections on my 17k

Hi Gang, we're only able to work on this a little at a time, appreciate you staying engaged. The Barker tongue jack arrived, beefy unit. It fit the top hole but not the bottom, had to open it up 1/16". Now it fits, haven't hooked it up yet.
Regarding the wiring mess, you were right Boomerweps, the red 10ga wire to green with the 30 amp fuse is the solar charging circuit. Pulled the fuse and the controller goes dead. FWIW this controller and the larger solar panel looks to have been added after the trailer was built.
Of the (2) 8ga wires we know one is the parallel connection between the batteries and we agree Grit dog, it should be larger 4ga. We'll address that when we switch to the golf cart batteries.
Still don't know about the second one, could it be connected to the starter motor on the generator? Guess we'll disconnect it and try that.
We see what you did CA Traveler with the copper tube bus bar. Clever, you're able to keep some things always connected to battery power and the things you want to turn off go through the disconnect switch. Not sure what we will end up doing, appreciate the idea.
We'll update as we learn more. Thanks again!

Fwiw “pulling wires off the circuit while hot” is what happens anytime you disconnect the battery. Not an issue. Don’t overcomplicate this. Although sounds like you may have figgered out mostly what they’re all for now.

Some rigs have a terminal strip on the inside of the unit. Check under an item such as seat or gaucho for it.

If you purchase a clamp meter make sure it can measure DC amps. Expect to pay at least $30. Anything cheaper will most likely not measure DC.

Thanks for all the responses. At the moment there is no electric tongue jack installed, we removed the Atwood unit the Nash came with. The motor turns but no movement from the ram. We took it apart, a bearing boss for one of the shaft ends in the plastic gearbox failed, poor material/design in our opinion. The similar unit on our 2003 AF worked flawlessly for 20 years, still going. Its a shame really - the motor, switches, cover, bevel gears, etc. are all like new. Hate to scrap it but we have an American made Barker on the way. If anyone wants the Atwood for spare parts you can have it, we are 90 minutes south of Portland, OR. There was a single lead with an eye terminal from it to the positive battery terminal with the other connections, that is only thing we've removed so far. Everything else is unchanged as we bought it from the original owner, an older gentleman. He is beyond assisting with this.

Thanks enblethen, responses:
30-amp fuse could be for the electric tongue jack.
> No jack/wiring installed at this time.
Number 4-gauge wire should be power to the 12-volt distribution panel.
> Agreed, we need to find this panel.
Should be a number 10 wire going to the umbilical cord to tow vehicle.
> If it is, the connection must be made inside, we'll look.
Number 8 wire could be for the solar panel controller.
> We think so too, need to figure how to test for it without damaging the controller.
Should be another small wire 10-12 for the break-away switch. Battery disconnect should not disconnect break-away switch!
> The only direct connection to the tow vehicle is the standard 7 pin plug and cable. Taped to it, where it comes out of the body of the trailer are a pair of black small gauge leads, look to be 14ga. These connect to the breakaway switch. There is no visible connection of this switch to the batteries, if it is it's done inside. We understand the safety comment made about not having these on a battery disconnect switch.

We're reluctant to pull wires on/off the battery when circuits are hot, guess we better invest in a clamp-on current meter. We'll do some homework and get back to the forum. Thanks!!

I have taken time to label every wire running to the house batteries. Tape will do it but do yourself a favor and package of colored zip ties. I have a package that has 5 colors in the package. They are the small tiny zip ties so they look decent. I took my owners manual and made a list of the colors and put description of each color and where they go on the battery. Some of the little wires I put 3 to 4 together and zip tied them together to where they would always go to the correct place. this has helped me big time over the years to taking my batteries out and cleaning them and the area they rest in. I have my batteries out right now for testing and cleaning but once I get them back in I can take a photo an post it so it makes more sense!! Hope this helps someone . Dad

I take photos each time I replace batteries. Safety is a good idea either way

In your spare time check that the 2 solar panels are compatible since they are different sizes. If not then the solar may not be optimal but adequate.

I suspect the 30 amp blade fuse is the solar connection. Do you have a solar controller? If so, disconnect the solar panel input to the controller (or cover the panels), then pull the 30 amp fuse. Does your power tongue jack still work? If so, that fuse is the solar input to charge the batteries. Solar panel input to a controller not connected to a battery can damage the controller so I would not just pull the fuse to see what happens.
With the solar input safely disconnected, you can remove the other positive connections and test which one still has 12vdc coming from the converter. That will also be connected to your 12vdc main line. Be careful, do not allow it to be shorted to ground.
As another suggested, you should mark your cables where they all go. Mark the positive ends with red electrical tape or shrink wrap and the negative ends with black tape or shrink wrap IF they are not the correct color to start with. This will simplify future electrical issues.

The parallel jumpers are too small.
The rest, not sure what the question is. Disconnect them 1 at a time and see what doesn’t work.