Trickle Charge - A charge at a low rate, balancing losses through local action and/or periodic discharge, to maintain a cell or battery in a fully charged condition.
Voltage Depression - An abnormal drop in voltage below expected values during the discharge of a battery.
Power Sag - Voltage below 80% to 85% of rated RMS voltage for one or more cycles.
Safety Vent - A venting mechanism designed into a cell which activates under specific conditions of abuse to relieve internal pressure.
Dry Cell - A cell with immobilized electrolyte. The term "dry cell" is often used to describe the Leclanche cell.
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.
Bypass (manual) - Manually-operated switch used to supply the load via direct connection to utility power during servicing of the UPS system.