Question regarding alternative way of charging plane.

Will it be ok to hook up a 9volt DC charger directly into the battery compartment of the transmitter and then use the transmitter in it's normal way to charge the plane?

I have 2 AA planes. I use one to charge 1 plane while I fly the other. Rechargeable batteries are ok, but they died quickly, so I was thinking of hooking up an AC Transformer that outputs 9Volt DC hooked directly to where the batteries normally go. The transformer should not notice any differences since it's getting power from the 9Volt transformer instead of the 6 1.5volt batteries. Or am I missing something here?