Nowhere in the manual does it state that they recommend that battery. Fact is, thats all they ship with it. You are more than welcome to fly your 900.......right into the ground! When the voltage drops below a threshold voltage the reciever drops out and has to re-bind and come back. Larger batteries have more reserve and are less prone to dropping below the threshold voltage under load - period! Read the posts in the JR section then come back and tell us all about the 900! You will convince very few to use minimal amperage with a DX7 around here!