Agreed, since the 148 only draws .8 milliamps when idle, the load to the battery packs is almost nil at 3.6 milliamps plus the receiver draw, 30 milliamps at rest using a Futaba R2004GF in this example. With a combined load of 33.6 milliamps at rest, you could leave the receiver on for 20+ hours before the battery pack failed, if fully charged. Obviously, when in flight, the load is greatly increased. If you were using the higher performance and/or digital type servos, all specify that they have a high current draw so a larger pack would be needed for equal flight time. One thing to be aware of is that with the 148 servos, if you use a 6 volt pack, the speed and torque are both 25% greater. The speed won't be an issue as it's only .06 seconds faster lock to lock. The higher torque would, however, allow the use of larger control surfaces or require a lower current draw for smaller ones