I've got a 4-A cell 2100mAh NiMH batt pack in my Raptor 50 V2, and it lasts me about 5 tanks on a full charge. I've got a 9CH PCM RX, 3 Futaba S9252 servos, one S9001, and a GY401/S9254 gyro/servo combo running of of it. Got it from
http://www.cheapbatterypacks.com for about $18 or so...