12V System switch

[AndyRonLI]

Folks,
I have a 2019 Montana High Country 321 MK
I am switching out to lithium batteries to get some minor dry camping capability. So swapping out the converter/charger to a Li compatible one and adding a 12v/12v isolation between the tow vehicle 12V and trailer 12V system to limit alternator draw.
When I pulled out the existing converter charger, I found two short runs of 6ga wire. The hot goes directly to the load center hot and the ground goes to a bus bar mounted directly behind the load center.
So... How does the 12V kill switch in the wet bay work?
Is there a relay in the load center somewhere?

It certainly cant interrupt current to the load center as it is directly wired to the converter/charger.


I know it works.
But how?
Any help is appreciated.
Thanks
ANdy

[rames14]

Andy, the switch in the convenience center only shuts off certain circuits. Unless you put a cutoff switch on the battery itself, your landing gear, slides, CO detector and smoke detectors will still be live. That is why you see posts with people with dead batteries. Two simple ways to solve, put a cutoff switch in with your new batteries or use a solar or conventional trickle charger. With your solar, it won’t be an issue. Good luck with the upgrade. You will love lithium batteries. I have a BIM for Dc-Dc charging and with the solar, I never worry anymore.

[BB_TX]

Is there a second large wire to the 12 vdc load center hot? The converter is always connected to the load center. The 12 vdc disconnect switch disconnects the battery from the load center.

[AndyRonLI]

Yes there are two large red 6 gauge wires.

One definitely comes from the converter.
The other goes to... the battery via the isolation switch?
My confusion is there are several large gauge wires to the battery.
One clearly goes to the inverter with its own idolator switch and 50 A breaker.
Its not clear where the other two go, and thus their purpose is unclear.
One of those two is a single tap from a 50 amp breaker.
The other of those two is on another breaker and shares a breaker terminal post with what I think are the hot 12V line from the vehicle, the awning, and slides.
I suspect that the line that shares a terminal post with the tow vehicle +12V is from the load center. I will check that out when I get the new load center running installed.

I really wish they had stuck labels on this stuff.
Thanks
ANdy

[AndyRonLI]

For what its worth, this is a circuit diagram I came up with.
Its all guess work, except the 12V from the trailer plug I have directly traced.
Thanks
ANdy

[BB_TX]

Originally Posted by AndyRonLI

.............
My confusion is there are several large gauge wires to the battery.
One clearly goes to the inverter with its own idolator switch and 50 A breaker.
Its not clear where the other two go, and thus their purpose is unclear.
.................

Without seeing a picture of yours, I am guessing you have 3 auto reset circuit breakers. One feeds the inverter. One feeds the hydraulic pump. And the third feeds everything else, including the load center thru the battery disconnect switch. In addition, there a likely some smaller wires connected to one or more of those breakers and likely have inline fuses feeding various other things.


And yeah, a schematic diagram from Keystone, or at least some wire labeling, would be nice.