Was a few minutes into my 7th battery pack and noticed that my K2 seemed to loose power. Found that the positive cable at the motor was loose and that there was some corrosion on the terminal. You'd swear they used acid core solder on the terminal! Better to go brushless rather then risk a crash with the stock brushed motor and ESC if you ask me. Must say that these K2s sure are smooth and stable for the money none the less.