Why not use the Li-Fe Battery of Hyperion?
I leave some photos, also there are for futaba 4pk (6.6v), kopropo helios (4+4) ...
Where to buy:
http://www.positivonegativo.com/tien...wCat&catId=123
Connector:
http://www.positivonegativo.com/tien...wCat&catId=124
