I bought a RK Electronics battery management system for my rx & tx packs, it also has a (aux) channel , this seems to be a late 80 early 90s system. It discharges,charges and then returns to trickle charge on all 3 channels. The rx is marked (4 & 5 cell packs) and the tx (8 & 9 cell) packs but the aux dosent say what voltage or # of cells its for? I didnt get any instructions with this unit so does anyone know what this aux is for ? It has a digital readout but only displays discharge current in ma there is no readout for any of the three charging outputs.