I once to had the same problem, i thought i could use the controller mod to get both AA for a good charge for my dual laymans mod. i was damn wrong haha
if you do that u might get like half a minute outta the charge,i have to use 4 AA, it works a little for my tri cell laymans but not well enough, thats a future project ! What u should do if you dont have a battery holder and have a KIT racer, crack open the controller and take the 2 AA holde out of that and wire it to the opposite side of the charger( side w/o the red and black wires going into the controller) it usualy has a blue or white wire contecting the - and + side. I snipped those wires and soldered the wires form the KIT racer battery holder to it and theholder to the charging padand VWALLA 4 AA battrey charger ! its ghetto, but hell it works like a charm !
ill send pics if i confused u ha