IR Drop - A voltage drop associated with the electrical resistance (R) of a battery or current flow (I). The voltage drop is the product of the current (in amperes) and the resistance (in ohms).
Power Surge - Voltage above 110% of rated RMS voltage for one or more cycles.
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.
Voltage-Keyed - A system which incorporates a mechanical identifier on batteries and devices to ensure only batteries of the correct voltage are connected to the device.
Top-Up Charge - A low rate charge following the main charge, designed to ensure maximum capacity.
Percent load - Ratio between the power Pu drawn by the load and the rated output Pn of a UPS system (Pu/Pn). Sometimes referred to as the load factor.
Ambient Humidity - The average humidity of the surroundings.
