Aquacraft Mini Rio batteries
#2

You might try these, though you may have to change the connectors:
http://www3.towerhobbies.com/cgi-bin...?&I=LXEAXV&P=0
http://www3.towerhobbies.com/cgi-bin...?&I=LXFGLW&P=0
http://www3.towerhobbies.com/cgi-bin...?&I=LXEAXV&P=0
http://www3.towerhobbies.com/cgi-bin...?&I=LXFGLW&P=0