As I mentioned before, the best place to access the battery communications port is on battery #4 (see drawing above) due to the fact that it has an unused port with a rubber cap. If you take a look at the battery section of the wiring diagram that I included here, the battery data cabling goes from the VCU and starts with battery #3, then goes to #2, then #1, then #6, then 5, and ends at #4.