Internal Impedance - The opposition exhibited by a circuit element (cell or battery) to the flow of an alternating current (a.c.) of a particular frequency as a result of resistance, induction and capacitance.
Switching Transients - Rapid voltage peak up to 20,000 volts with a duration of 10mS to 100mS.
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.
Ambient Humidity - The average humidity of the surroundings.
End Voltage (also see Cutoff Voltage) - The prescribed voltage at which the discharge (or charge, if end-of-charge voltage) of a battery may be considered complete.
Inverter (off-line or stand-by) - UPS configuration in which the inverter is parallel-mounted to the load supply line and backs up the mains. This configuration offers a substantial cost reduction but is applicable only to low outputs, under 3 kVA, because it results in an interruption lasting up to 10 ms during transfer and does not filter inrush currents.
Nominal Voltage - The characteristic operating voltage or rated voltage of a battery.
