i am running 8 cell 2400mah nicd. your 7 cell will work, just make sure you program the controller for option 2(cutoff voltage=5.0v)if you want to. Of course, Flying fish is correct in stating Lipos, but since it is a cost thing(just finnished my logo103d with an 8000mah lipo at $300)as well as more power. Im only running a pheonix 25 with no problems, but if i was to go lipos in the future, i will get a pheonix 45.