Power Cells are used for just about any energy tool/weapon besides the standard laser rifles. Rather than serve as literal ammunition the cells are really used to power the weapon; but considering they are really the only part of the tool/weapon that gets depleted with each use they are commonly referred to as ammunition and are also collected as such. Cells can be found in packs of 10 or they can be removed from weapons you come across. A repeater or a fusion cutter will hold 30 cells, and a concussion rifle will hold 100. You can hold up to 500 at any one time. Droids are good sources for cells, as are the concussion rifles Trandoshans usually carry.