Thanks.
The V3 is 6v, but from my understanding there's no difference in wiring, or operation for that matter, other than the battery meter calibration.
The ecocharge's are 7.2v, so I'm going with pin 3 (+), pin 2 (-).
I suppose I'll just take off the mini-XLR for my V3 cable, and wire a 4-pin XLR on.