You may be right about it being the voltage and not the capacity. I only have 1 set of flights outside (all 3 batteries)since I changed the motors . The problem arose with the old motors and the new 180's do the same . I bought the batteries about 2 weeks apart and all do the same thing.I have done a flight inside just a straight hover and it to lasted about 5 min.I havent personally timed it but notice the shorter running time.Will the DN batteries charge "safely" with the stock charger?For all I know the charger's my problem. The charge time seems the same. O'well more $$$$$$$$$$$.[sm=spinnyeyes.gif]