I ordered a Venom 700mah 35c battery for my Nihui U807....Since the battery has a micro losi connector on it ,im going to give it a try in the X5 before converting to a JST plug to fit the Nihui. So the batteries ill be testing are. 1.) Stock Syma 500mah 20C 2.) No name china 500mah 25c (advertised 25c, who knows) 3.) Venom Drone 600mah 30c 4.) Venom 700mah 35c There is one battery i keep hearing is a very good and very powerful battery sold by MMW...My Lipo.de 480mah 40c battery This battery is highly regarded for those with the little custom micro quads using powerful chaoli motors and custom FCB's...Ill probably pick up one in the near future to try out as well...They cost $7.99 plus shipping so, its not going to be cheap one.