Real sword makes a battery (9.6v 2000mah) that fits quite nicely with little hassle.
DO NOT remove or damage the clear wrap on your battery. Make sure the wires on the battery are down and to the left when you put it in, it can be finicky and require some patience until you get the hang of it just work it in slowly. If you look at the gas tube (upper handguard) you can see a cut out for the wires to pass through (bottom left), the battery is meant (but not necessary) to be slid into the gas tube. Sliding the battery into the gas tube will make the dust cover easier to close as you won't have an excess of wires to deal with. There is little room for error or a battery that in not straight with all the cells lined up perfectly. You may find that a little strategic dremiling will make the process less cumbersome.
Last edited by Kozzie; April 10th, 2012 at 22:05..