Ok Isee what you're saying about the voltage difference thats something that Iforgot about the, 4 AA batteries @ 1.2 volts each makes a total of 4.8 Volts vs the Hump Pack at 1.2 volts X 5 which equals 6 volts.
Thanks for clearing this up, I just wasnt using my noggin and forgot about those rechargableAA's being 1.2V instead of 1.5V
Those would be good for the receiver though so Iwill just get some for that...
ORIGINAL: foxys
those are full AA batteries, most hump packs are 2/3 aa and have 5 cells rather then 4, more voltage means faster servos, they are 2/3 size to fit all those cells in the battery compartment. With full size aa your limited to 4 cells, so your servos will be slower.