thanks that did help I have 6 2100 packs with some cycles on them from my T-Rex 450 so the heli and plabe will share packs but i do have the 1 3S3000 pack like you said i will try it after i get it flying on the 2100 packs the weight is only 1 oz more so it should give me long sport flights like i want the 4000 adds 2.5 ozs