I didn't see any studs (other than the main 125A fuse). There is a large two-pronged red/blk connector center-rear on the fuse block, but some sources say that is for fuel pump, and it's also an 8ga wire.

Whoever engineered the van fuse block needs a good slap in the face (for reasons other than just this problem). If you design it so that you have to get filthy by reaching past wires, hoses, and a hydroboost so that you can rip off fingernails and scrape knuckles just to open the fuse box, maybe you should be a doctor or a teacher because engineering and design is probably not your greatest aptitude. The other thing I can't seem to figure out is why there is nothing said about it in factory service manuals, haynes manuals, or even on google. Even the things you find on google are things that worked great for username ExpressVan2341, but don't apply for how my van was wired.

The nice part about the trucks is that they have those lock-in levers that let you access the bottom. Vans are just bolted down.

I'll take another whack at it tomorrow. If it proves too crazy, I'm going scorched earth... hardcore. My plan:


This way I'll have camping batteries (located in a bucket where the spare used to be) that can be connected to the main battery all the time, none of the time, or only when there is oil pressure (engine running). Drain the camping batteries? switch to the middle and start the engine. As soon as it gets oil pressure, the solenoid joins the banks for charging. Need to isolate the rear or front? switch to the right to make sure they don't connect. Drain the starting battery? Switch to the left and command the rear batteries to "jump start" the van.

I realize that depending on which solenoid I choose, the supply and switching may need to be done with a relay, but this is my quick and dirty sketch of the campervan setup I plan. If I can't get 12v to the red/blk in the 7-pole connector, I will just wait until I enact the above plan and then draw 12v for the trailer from the camping batteries. Not only does that kill two birds with one electrical installation, it prevents killing the starting battery if I ever do something like tow a travel trailer for boondocking. I can suck all the rear batteries down without killing the starting battery.

Then the fun part is seeing how much smoke my alternator makes when it gets smacked with all that charging amperage

 

Here’s a partial screenshot of the wiring diagram I found. It looks like there could be 2 separate battery power wires to the 7 way blunt cut.

 

Fuse 13 is a mini fuse and is red/wht to feed the under-dash blunt cuts for brake controller. Fuse 50 is a J-type fuse and feeds red/blk for the rear 7-pole blunt cut.

The screenshot is much appreciated. Nice to see it so clearly laid out.

 

I agree the fuse block location is awful. Besides just trying to access it, I’ve replaced 2 of them in the past year on customer vans (one express, one cutaway) that shorted out due to either brake or power steering fluid being spilled on them. The covers aren’t 100% sealed (not that they should be) but you’d think they at least anticipated the possibility of fluid exposure due to leaks.

Apparently they didn’t.

Are your camper batteries going to be deep cycle or dry cell? If so, you’ll want to consider installing a similar type for a cranking battery. I can’t recall all the details when charging standard flooded type vs. deep cycle vs. dry cell but I’m sure that mixing types will definitely burn out the alternator.

You might also want to consult a shop in your area that specializes in electrical systems (starter and alternator service) and see if they have recommended alternators to install for this set up.