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.
Metal Hydride - An intermetallic compound or alloy in which hydrogen has been absorbed; also, the negative electrode in a nickel-metal hydride battery.
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.
Positive Temperature Coefficient (PTC) - A thermally reactive device which becomes highly resistive at a specific temperature or current.
Constant Power Discharge - A battery discharge regime whereby the current during the discharge increases as the battery voltage decreases.
Voltage (float) - DC voltage applied to the battery to maintain its charge level. This voltage depends on the type of battery, the number of cells and the manufacturer's recommendations.
Cutoff Voltage (also see End Voltage) - The battery voltage at which the discharge is terminated. The cutoff voltage is specified by the battery manufacturer and is generally a function of discharge rate.
