Depending on the plane size, I have used two batteries in parallel for the rx. BTW, I do not recommend using a digital servo on your throttle when setting up a glow plane. Ive had more then one burn up on the throttle channel almost causing the lost of the planes they were in. Somethign to do with their "desire" to constantly self-center themselves and being held a certain location(liek soemwhere in the throttle range) for extended periods of time.