I noted a reply, stating an effort to disconnect a battery lead which would stop discharges from the battery when not in use... CO detectors and such.
IMHO EVERYONE should consider a main breaker and a revamping of the wiring to the batteries.
One can get these from stores such as West Marine and the like. They are simple switches which will handle the 12v load. BE SURE to use a switch that is MORE THAN adequate. Normal switches WILL NOT handle the RVís startup and usage loads.
I think itís a safety issue whereby disconnecting a lead(s) before one works on the electrics is important.
Second, grounding to the frame is customary, but the ground is generally the first place I look when something doesnít work. Corrosion is a problem, consider dielectric grease where possible.
Third, individualizing the connections, i.e.: one lug for the radios, one for the CO detector, and so on where possible, makes troubleshooting easier, not to mention overloading the connection point. Nothingís worse than having corrosion between crimp connections where one piece of equipment works and the other doesnít.
So, add a buss bar on both the positive and negative side along with your master switch. Remember to calculate the load first, and purchase proper materials. For the do-it-yourself folks, itís not expensive and just may save you and your RV.
Just a thought