"Pick up 2 fuel cells" is an objective in the Story Mission Plan B in Borderlands 2
Walkthrough
Scooter will give you 4 pieces of Eridium and tell you that you need to find 2 fuel cells.
One Fuel Cell is found to the left of Scooter. Look for the Washing Machines and look at the rack to the left of it. On the bottom shelf you will find the Fuel Cell.
One is found on the walkway above you in the mechanic's shop. Go up the stairs and turn over to the left. Look at the rack just before the lockers on the right. You will find the Fuel Cell there:
