What did you do with your batteries after the competition last year? Lead acid batteries like the ones we use must be maintained, not just thrown in a closet. They should be occasionally put on charge and topped up. If a battery was discharged and left to sit, its condition will degrade over time and the capacity will diminish. The addage "Use it or lose it" should be followed when caring for your batteries.
I would bet that your batteries have perished due to poor storage practice or are defective.
Charge your batteries up, then get yourself a battery load tester like this one
http://www.princessauto.com/pal/prod...ry-Load-Tester. If the cables and clamps attached to the tester are any smaller than the type of wire we use to connect the battery to the robot (6 gauge) then it's not a proper load tester. Test the batteries under load to see if they are defective. You can also take them (fully charged of course) to an automotive shop and ask them to test them with a similar load tester. Some autoparts stores offer free alternator and battery testing and will also have the equipment to perform a similar load test.
A voltmeter will not tell you if the batteries are good. They must be loaded heavily and the voltage drop measured to determine if they are truly good or defective.