The process aimed at reducing the non-uniform conditions in electricity demand. Load-leveling aims to store energy when demand is low, and use this stored energy to meet peak demand. Metal: Material with partially filled valence band and located in the left and lower portion of the periodic table. Characterized by high thermal and electrical conductivities. Memory Effect: A phenomenon in which a cell, operated in successive cycles to the same, but less than full depth of discharge, temporarily experiences a depression of its discharge voltage and subsequent loss of the remainder of its capacity at normal voltage levels. Nominal Voltage: The characteristic operating voltage or rated voltage of a battery.