My Blade MCX2 with a brand new 160ma 25C battery will fly for less than one minute before slowly settling into ground effect. It has very poor vertical acceleration. All other aspects of flight are ok. I have tried a second battery with the same results. I don't think there are issues with the batteries or chargers. The helicopter flew well when new and has not had any hard impacts into walls, floor, etc. I have had other electrics that seem to suffer the same fate. I am becoming disallusioned with electric helicopters. Does anyone have a solution to this apparent loss of vertical power?