Need more voltage then the 4 AA's RX BEC pack...what upgrade?

[BrianG]

Couple of things here:

1) Boosting the voltage will not improve the radio range, especially on the receiving end.

2) I assume you mean 4 Alkaline AA's (not rechargeable)? If you want rechargeables, a 5-cell NiMH pack can be purchased fairly cheap. That will be 6v @1.2v/cell, but will be slightly higher off the charger.

3) Overvolting servos will give them more speed and power, but at the expense of possibly burning them up. Just like our BL setups, more voltage on a particular setup will draw more current and create more heat.

4) To get more runtime, you need higher capacity, which usually means physically larger/heavier cells.

5) Best way to go about this is to use a UBEC. It's lighter/smaller than any receiver pack, and will provide as much runtime as your main batteries can dish out.