a123 question

[BrianG]

On any 3s pack, there are 4 cell connections, two of which are the main power leads. That leaves the two inner connections. Most other packs have the main power leads attached to the same point as two of the balance leads, so there are 4 balance wires in all. The A123 pack must have the main power leads AND the balance connector hooked up to a balancer to operate properly.

Same idea with 2s Trakpower lipos; there are 3 connections, but there is only one balance lead (the inner one), and they are using the outer two as balance wires and for the main charge current.