IEC - The International Electrotechnical Commission (IEC) is the leading global organization that prepares and publishes international standards for all electrical, electronic and related technologies.
Immobilised electrolyte - A construction technique used in lead-acid batteries. The electrolyte (the acid) is held in place against the plates instead of being a free-flowing liquid. The two most common techniques are Gel Cell and Absorbed Glass Mat.
Impedance - A measure of the response of an electric circuit to an electric current. The actual value is frequency dependent. The current is opposed by the capacitance, inductance and resistance of the circuit.
Impedance testing - Determination of the battery’s internal impedance by measuring the voltage drop across a cell when it carries a sample alternating current.
Inductance (L) - A measure of the ability of a device to store magnetic flux per unit of rate of change of current passing through the device. Measured in Henries. The voltage across the inductor is given by the relationship v = -L d/dtI(t)
Intelligent battery - Battery containing circuitry enabling some communication between the battery and the application or with the charger.
Intelligent charger - Charger which is able to react to inputs from an intelligent battery to control or optimize the charging process.
Internal impedance - Resistance to the flow of AC current within a cell. It takes into account the capacitive effect of the plates forming the electrodes.
Internal resistance - Resistance to the flow of DC electric current within a cell, causing a voltage drop across the cell in closed circuit proportional to the current drain from the cell. A low internal impedance is usually required for a high rate cell.
Inverter - An electrical circuit which generates a sine-wave output (regulated and without breaks) using the DC current supplied by the rectifier-charger or the battery. The primary elements of the inverter are the DC/AC converter, a regulation system and an output filter.
Ion - An atom or group of atoms which is electrically charged. Depending on how they were created – through release or absorption of electrons – ions can be either positively charged (Cations) or negatively charged (Anions).
IR drop - The voltage drop across a battery due to its internal impedance. See also Ohmic loss below.