One of my Powerbox evolution has a problem. As known there are 2 battery port on it, At the end of my ech flying date I found that one port draws much more(%40 pct about) then other port. I mean I have 2 ea 2s 7.4 V 3.500 Mah battery pack and when I charge first one takes 500 mah other one takes 700-750 mah. I checked many times , What is the problem? Battery or??