Originally Posted by simplechamp

What you want to do is run an external BEC that can be adjusted to 7.4V (the Castle BEC is the way to go here!). So you power the external BEC from your main battery, and you don't need any extra RX pack or anything.

Here is a diagram from Castle, I highly recommend their BEC: http://www.castlecreations.com/produ...ec_wiring.html

You can use a lipo RX pack, but to me it makes more sense to use a BEC since you already have a powerful 4-6S voltage source in the main lipo packs. Just need to step the voltage down to a level the servos and RX can use. A lipo RX pack will be larger and weigh more than a BEC, and it's also an extra battery to worry about charging and monitoring, and the voltage won't be constant. Lipo RX pack is only suited for nitro the way I see it.