Originally Posted by jim27358
No sure about yours but anytime mine is connected to shore power it turns on anything that is connected to the house electric circuits. Mines a Newmar.
You can disconnect the negative terminal from the batteries and isolate them saves the chance of arching.
I need to turn on the salesman's switch, otherwise my 12v system is not functional, even when plugged into shore power, however the 120Vac system is up and running, so the charger for the house batteries is working.
A couple of years ago I posted a question about a hot relay. CHBoone posted a reply, giving a link to a trouble-shooting guide for the Battery Control Center. I just re-read the "Battery Interconnect Function" part of that guide, and it seems that, when the COACH batteries are charged to 13.2vdc or greater, a "Comparator" circuit turns on a relay, connecting the coach batteries with the chassis batteries, enabling both sets to be charged together.
If the Comparator reads 13.2vdc on the coach side and ZERO-vdc on the chassis side, I have to assume that it turns on the relay, feeding 13.2vdc to the chassis electrical system, thereby energizing the chassis system as it tries to charge the chassis batteries. This is likely the source of my power to the CB radio, map lights, cigarette lighters, ignition, rear-view camera monitor, and headlight switch.
I further suspect that, although I am reading the charging voltage in the chassis system, the relay likely limits the amperage, therefore, turning on a high-draw item like the headlights, probably draws down all the current in the system.
Although I'm making quite a few assumptions here, I suspect this may be the 'gremlin' in my system. It's working as its supposed to work, albeit, without the chassis batteries being connected, there isn't much power energizing the chassis electrical system, but it IS energized.
Thanks again to CHBoone for the link to the trouble-shooting guide a couple of years ago. It is full of great information.