large batteries

Hav one of those KWA G36Cs, its a lovely gun with an insane rate of fire,,,,,but thats the problem,,it states that the gun should be used with an 8.4v mini(i think the largest is a 1450mah),,,far to small a battery to put that kind of workload on to,,,anyway ive read that the gun can take large type batteries because it has a large handgrip,,,,,is this true..