Originally posted by Lynx
Just on general principals I'd say the higher voltage pack would be mildly more efficient.
It's actually the opposite, That is one drawback to running a 6 volt pack, You need more capacity. With the higher voltage, you also have more current, which is why you get more torque, and more speed, but the higher current draw drains the battery quicker
Originally posted by Lynx .
The BEC circuit in transmitters is usually 3.3 volts I believe.
Doesn' t "BEC" refer to "battery eliminator circuit?" This applies to electric cars where the main battery pack powers the motor and the receiver, But that is contradictory in this case, we are discussing the very component that the BEC eliminates, ( the receiver battery)
Some servos do not work on 6 volts, (Futaba coreless come to mind) they will jitter constantly and won't stay centered, you must run a regulator for those. Even servos designed for 6 volts, are really getting well over 7 if the pack has just come off charge, so untill the surface charge is gone, even "regular" servos may jitter. The advatages of a regulator is that the voltage stays constant, (somewhere around 5.2-5.4 volts depending on the regulator) this gives you slightly more torque and speed than a 4 cell pack, but prevents the high peak voltages from doing any harm. Also as you fly, and the battery voltage goes down, the voltage at the servos remains constant, therefore the servo speed, torque, and "feel" remain constant, (many pattern fliers charge their batteries before each flight for this same reason) There are no disadvantages to a regulator except you have one more component to buy and install. The advantage of No regulator, is simple installation, and you will probably be ok 99% of the time.