chasis battery not charging; house battery cooked

Check all your connections to make sure phase is correct. Check input and output voltages as Mex suggested.

Connecting anything electrical by relying on wire length or color of jacket is an invitation for problems. I'd suggest that you take the brand and model number of the isolator and find the exact pinout of the connections. Most brands publish a data sheet of their product that will show connections in a schematic drawing.