I use two independant Nicad or NiMh (like Eddie is saying) packs into two good switch harnesses into the Multiplex 12 ch receiver. That RX has a built in isolation circuit and always draws from the strong pack. If your receiver does not have this built in, you can use the Electrodynamics Battery Back R, or some similar product. In addition, I have an Electrodynamics voltage display unit. When I am ready to fly, I power up one pack, wiggle the servos and check voltage, turn #2 on and #1 off, do the check again, then turn #1 back on and fly. Works great!