connecting "in-series" batteries

Just wanted to give an update that I was able to use my multi-meter and tracing back the wires to figure out the wiring and connect my new batteries successfully. The two white wires are ground, the red wire supplies voltage to the batteries to charge them (reads about 13.5 volts when connected to shore power) and the black wire is also a power wire that goes to the 7-way hookup. Thanks for the diagram and website link "Pianotuna". I hooked it up the way you suggested.


Thanks to everyone who provided input and advice!