Go to volcanic Crater and go on the mine carts to the opening of Spider Cave. Now turn around and you will see a little metal box on the rock. (It's higher than your head so go to first person view mode and go to very edge to see it.) Now that you know where the box is, go in spider cave. Find the closes yellow Eco vent to the entrance of the cave. Power up and run as fast as you can out of the cave to the rock. To make the trip faster use rolling jumps. (run press R1 or L1 than you roll than press x and you do a long leap) and when your at the rock get to the edge or close enough and jump press box to shoot a yellow eco ball and it should home in and explode the box. The power cell comes out, get it. To find more power cells you didn't find go to the strategy guide on this site. It really helps.