What is the maximum battery space dimensions in the handguard for the ICS L85A2 AEG?

I'm trying to find out the best battery that can fit into the hand guard. I know that a large Ni-Cad 1700mAh 9.6V battery can fit into the handguard, as shown in the reviews. However, will it fit any other types of large batteries? If you recommend any good batteries please give me link. (I will only accept 9.6V batteries only)