Capacity - The total number of ampere-hours or watt-hours that can be withdrawn from a fully charged cell or battery under specified conditions of discharge.
Rated Capacity - The number of ampere-hours a battery can deliver under specific conditions (e.g., rate of discharge, end voltage, temperature); usually specified by the battery manufacturer.
C-Rate (also see Hourly Rate) - Discharge or charge current, in amperes, expressed in multiples of the rated capacity. For example, C/10 discharge current for a battery rated at 1.5 Ah is:
Cathode - The electrode in an electrochemical cell where reduction takes place. During discharge, the positive electrode of the cell is the cathode. During charge in a rechargeable battery, the negative electrode is the cathode.
Rectifier/charger - UPS component that draws on the mains the power required to supply the inverter and to float charge or recharge the battery. The alternating input current is rectified and then distributed to the inverter and the battery.
Top-Up Charge - A low rate charge following the main charge, designed to ensure maximum capacity.
Bypass (manual) - Manually-operated switch used to supply the load via direct connection to utility power during servicing of the UPS system.
