My 50CC setups.
1 2500Mah A123 Battery, dual outputs (all from Wrongwayrc.com)
1 output to a JR HD switch, to the reciever.
1 output to a JR HD switch, to a RC EXcel Optical Kill, to a voltage drop diode, to the ignition.
All are 5x 7955 or Savox 1256tg and a throttle servo

(3 planes, hundreds of flights, no battery/power system issues)

My 100CC Pawnee.
2 2300 Mah A123's one straight to the Power Safe Reciever
1 dual lead wired as above.