RE: Brownouts....
Brown outs can be caused by things other than an insufficient battery. The wiring between the battery (no matter how good or big the battery) can cause a brown out or momentary drop out if there is a high impedance in the path such as a switch that has corroded, a battery cable that has been damaged and had its cross section area decreased (like broken strands or poor crimp or poor solder joint) or a servo hanging up and drawing excessive current. That is why a Voltwatch or equivalent indicator is nice to have as, when you exercise the servos by rotating all sticks at one time and watch the indicators, if you see a red LED flashing, you have a problem as you are getting momentary voltage drop outs at the point the indicator is plugged in.