Eureka! Thanks for the photo.
That must be what is behind the side of my battery. Just the other day, I noticed there was battery cables going to something behind the battery, and I was not sure what it was as there is no way I can get to it without taking the battery out, and it has been too cold to investigate further.
Those are familiar to me as they come from the boating world. It looks like a Blue Sea series 285. I just bought one to put on the hydraulic lift circuit as they put in an auto-reset breaker, which while it will protect the circuit, will not allow you to disconnect it (you push in the red part to trip it).
I am going to re-wire the battery box area this year. I am going to replace the batteries, and I want to clean up the entire Rube Goldberg mess.
I am thinking of installing one of these hatches to the outside of the coach:
I want to put both the disconnect for the hydraulic lifters in there, as well as the one Thor put behind the battery, if indeed that is what it is. And if I have room, perhaps a solar battery charger plug.
But if I go this route, I need to make sure the existing cables will be long enough as I really don't want to run new cables. And I will probably have to buy thru-mount versions of the breakers as the existing ones are surface mount. And at $40 bucks per breaker, they ain't cheap.