ENERGY EFFICIENCY

"For a rechargeable battery: the fraction, usually expressed as a percentage, of the electrical energy stored in a battery by charging that is recoverable during discharging. For an electrolytic cell: the fraction, usually expressed as a percentage, calculated as the theoretically required energy divided by the energy actually consumed in the process (production of a chemical, electroplating, etc). Inefficiencies arise from current inefficiencies and the inevitable heat losses due to polarization. See also coulometric efficiency. "