Duty Cycle - The operating regime of a battery including factors such as charge and discharge rates, depth of discharge, cycle duration, and length of time in the standby mode.
Shelf Life - The duration of storage under specified conditions at the end of which the battery still retains the ability to give a specified performance.
Midpoint Voltage - The voltage of a battery midway in the discharge between the start of the discharge and the end voltage.
Backup time - Time during which the UPS can supply the rated load with nominal-quality power while the mains are down. This time depends on the battery and the efficiency of the UPS. Typical backup ranges from five minutes to several hours.
Rechargeable (or "Secondary") Battery - A galvanic battery which, after discharge, may be restored to the fully charged state by the passage of an electrical current through the cell in the opposite direction to that of discharge.
Cycle Life - The number of cycles under specified conditions which are available from a secondary battery before it fails to meet specified criteria as to performance.
COS phi - A measure of the phase shift between the current wave and the voltage wave observed at the terminals of a load supplied with AC power at a given frequency.
