Thats exactly what I found out. With two different chargers, theres no loop confusing the charge source. Charging both with the same unit creates a ground loop. This is why putting the little extension between one of the switches and a battery will help. That way I can go direct to one battery, and still charge both together. Either that or just charge the other three on the plane with the x4, and one rx battery with the hyperion. Either way, it's better than digging out batteries or messing up my restraints and neat wiring.