The invention relates to an improved apparatus and method for assembling a battery. The invention includes an improved apparatus and method for sealing a battery case closure to a battery case. The apparatus comprises a device for moving a carrier with fluid pressure through fluid conduits disposed internal a shaft. A novel case stop is disclosed for stopping and positioning a battery case on a support. A method is disclosed for heating a battery case with a case heater. A conveyor system is included for sequentially moving a plurality of flat battery components such as case closures.