The Plot Thickens.
Today I noticed a spark / arch coming out of the main switch when I turned on the batteries to power on the SCC (not the inverter). The trailer was pretty dark inside, which is why I had not seen a spark before. Odd. I open up the switch to find it had been arching. There is a burn mark where the switch first makes contact to close the DC connection of the 48v battery positive. The first position goes to a resistor, so this should have been limiting any call for large amount of current. Is this where/why the BMS is reading the short? Probably. But why is the switch arching?
So more testing.
HERE'S WHAT'S WEIRD:
I remove all battery cables from the battery terminals. I connected a DVM to the battery positive and connect the common of the DVM to the frame of the trailer. Only millivolts. BUT ... if I touch my finer to the negative battery terminal, I get 52.9vdc from the battery positive to the frame. Why? The floor of the trailer is wood. If I stand up with my shoes on and touch the battery negative there is only millivolts between the battery positive and frame. IF I take my shoes off and stand bare foot on the wood and just put my finger on the negative battery terminal, there is 52.9vdc between the battery positive and the frame. (Note: there are NO other cables connected to the 16s battery, just the busbars from cell to cell. )
Surely someone understands this?
But more importantly, Is this why I am getting an arch in my switch when the battery negative is grounded to the frame?