I cleaned up the batteries and traced the leads and here's what I found:
-The wet battery in my original pic had loose caps which allowed some acid to leak out. The lead plates are still covered in acid.
-All batteries measure 5.4 volts and if I measure the two series I get just over 13 for both "sets" of 6 volt batteries.
-The leads trace out as follows with numbers below corresponding to the numbers on the picture below.
1. positive lead to inverter
2. positive lead to starter I think. It goes up and over the engine.
3. negative lead to frame
4. negative lead to starter I think. Also goes up and over engine.
Note that the positive leads pull from different terminals as do the negative leads. Is this correct?
Recall that my symptom is that the batteries discharge very rapidly once i disconnect from shore power or generator even though the batteries show a full charge.
Additional thoughts?