Is there a shelf life to the batteries?

The ELC and ELP emergency drivers include NiCAD batteries. Nickel Cadmium batteries can be stored in either a charged or discharged state. However, long term storage can accelerate battery self-discharge, and lead to the deactivation of reactants. Although the cells can be stored at temperatures between -20°C and +45°C, as with almost all batteries heat can cause deterioration of the active chemicals and it is better to keep the cells in a cool, clean, dry, non-corrosive environment. After prolonged storage, two or three deep discharge cycles may be needed to restore full capacity. When storing for periods longer than a year or two, some performance decay can occur – NiCAD batteries that are on a shelf for longer than a year should be subjected to deep discharge/charge cycle to prevent this decay.