Hi Scott,

Are you sure your battery is 6.6 volts ? i`ve never heard of this before. Usually if it`s a ni-mh it will be multiples of 1.2 volts, normally 4.8 or 6.0 volts or if it`s a LI-PO, it will be multiples of 3.7volts, normally 7.4volts for a reciever pack which will require in most cases a step down regulator. If it`s a 4 or 5 cell ni-mh then it`s fine to use as is.

Hope some of this helps

john