I hit Rhal, and it had 34% left. When I hit it, it says he is already dispatched, so I loot him only to get nothing when 40m was put on him, but when I look at the guild homepage it says rhal is still alive and I try to join it again, but it says “Could not join raid. You are already a member of this raid.”
You can obtain power cells by completing daily quests located on the islands. The islands are outside of the main map and are in groups of five squares.