Well depending on the quality of the battery that initially came with your AEG you maybe fine, however it depends on how heavy you are on the trigger and how much juice your motor has to draw to complete a cycle, and by that I mean a gun with a stronger spring will need more power. In regards to MAH, the more MAH a battery has the longer is can run.
It would be a prudent course of action to purchase a secondary battery.
Is a website recommended by many members of this community, they have packs for airsoft and can also create custom packs to match your requirements.
Originally Posted by BrokenBird
Any of you built a multicell battery to put in a backpack and run a wire to the gun?
No, I personally not and cannot really see the benefit of doing so either.