RE: Great Planes Edge 540T
ADANAC18,
A bigger battery is always better as long as you can get the weight and balance right. With an 80 amp speed controller you wont have a problem on 4 cells. I was running a 5 cell on my scorpion 60 amp, i just limited the throttle to about 80% and had nice long run times. The best piece of equipment you can buy for brushless power is a watt meter, they are about 50 bucks. Plug it in and try different prop combos, get your amp draw where you want it and from that you can figure your run times based on you battery capacity.