Product Definitions

Battery, Solar & Energy Definitions

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Definition

Absorbent Glass Mat (AGM) The mat of microglass fibres which is used for filtering the sulphuric acid in lead batteries.
Acid Stratification When charging a lead acid cell, high density acid is produced in the plates. This heavy acid drops as a result of gravitation to the lower part of the cell while lower density acid rises to the top of the cell. This stratification of acid can cause loss of capacity and/or battery failure.
Active Material The active material in the positive plates is lead dioxide and that in the negative is metallic sponge lead. When an electrical circuit is created, these materials react with sulphuric acid during charging and discharging according to the following chemical reaction:
PbO2 + Pb + 2H2SO4 = 2PbSO4 + 2H2O
Ampere (Amp, A) The unit of measure of the electron flow, or current, through a circuit.
Ampere Hours (Amp-Hr, AH) A unit of measure for a battery’s electrical storage capacity, obtained by multiplying the current in amperes by the time in hours of discharge. (Example: A battery which delivers 5 amperes for 20 hours delivers 5 amperes x 20 hours = 100 Amp-Hr of capacity.)

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Battery An electrochemical device used to store energy. The term is usually applied to a group of two or more electric cells connected together electrically. In common usage, the term “battery” is also applied to a single cell, such as a AA battery.
Battery Capacity The electric output of a cell or battery on a service test delivered before the cell reaches a specified final electrical condition and may be expressed in ampere-hours, watt- hours, or similar units. The capacity in watt-hours is equal to the capacity in ampere-hours multiplied by the battery voltage.
Battery Charger A device capable of supplying electrical energy to a battery.
Battery-Charge Rate The current expressed in amperes (A) or milli amps (mA) at which a battery is charged.

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Capacity The ability of a fully charged battery to deliver a specified quantity of electricity (Amp-Hr, AH) at a given rate (Amp, A) over a definite period of time (Hr).
Cell The basic electrochemical current-producing unit in a battery consisting of a set of positive plates, negative plates, electrolyte, separators and casing. There are six cells in a 12-volt lead acid battery.
Charge Acceptance The quantity of current in ampere hours which a battery, in a defined charge state, can accept at a specified temperature and charge voltage within a defined period.
Circuit The path followed by a flow of electrons. A closed circuit is a complete path. An open circuit has a broken or disconnected path.
Cold Cranking Rating Number of amperes a lead acid battery at 0oF (-17.8oC) can deliver for 30 seconds and maintain at least 1.2 volts per cell.
Container The polypropylene or hard rubber case which holds the battery plates, straps and electrolyte.
Corrosion The destructive chemical reaction of a liquid electrolyte with a reactive material – e.g. dilute sulphuric acid on iron, producing corrosion products such as rust.
Cover The lid for the container
Current The rate of flow of electricity, or the movement of electrons along a conductor. The unit of measure for current is the ampere.
Cycle In a battery, one discharge plus one recharge equals one cycle.

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Deep Cycle A cycle in which the discharge is continued until the battery reaches it’s cut-off voltage, usually 80% of discharge.
Direct Current (DC) The type of electrical current that a battery can supply. One terminal is always positive and the other is always negative.
Discharge The conversion of the chemical energy of the battery into electric energy.
Depth of Discharge The amount of energy that has been removed from a battery (or battery pack). Usually expressed as a percentage of the total capacity of the battery. For example, 50% depth of discharge means that half of the energy in the battery has been used. 80% DOD means that eighty percent of the energy has been discharged, so the battery now holds only 20% of its full charge.
Discharge, deep Withdrawal of all electrical energy to the end-point voltage before the cell or battery is recharged.
Discharge, high-rate Withdrawal of large currents for short intervals of time, usually at a rate that would completely discharge a cell or battery in less than one hour.
Discharge, low-rate Withdrawal of small currents for long periods of time, usually longer than one hour.
Drain Withdrawal of current from a cell.
Dry Cell A primary cell in which the electrolyte is absorbed in a porous medium, or is otherwise restrained from flowing. Common practice limits the term “dry cell” to the Leclanch cell, which is the common commercial type.

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Electrochemical Couple The system of active materials within a cell that provides electrical energy storage through an electrochemical reaction.
Electrode An electrical conductor through which an electric current enters or leaves a conducting medium, whether it be an electrolytic solution, solid, molten mass, gas, or vacuum. For electrolytic solutions, many solids, and molten masses, an electrode is an electrical conductor at the surface of which a change occurs from conduction by electrons to conduction by ions. For gases and vacuum, the electrodes merely serve to conduct electricity to and from the medium.
Electrolyte A chemical compound which, when fused or dissolved in certain solvents, usually water, will conduct an electric current. All electrolytes in the fused state or in solution give rise to ions which conduct the electric current.
Electropositivity The degree to which an element in a galvanic cell will function as the positive element of the cell. An element with a large electropositivity will oxidize faster than an element with a smaller electropositivity.
End-of-Discharge Voltage The voltage of the battery at termination of a discharge.
Energy – Output Capability Expressed as capacity times voltage, or watt-hours.
Energy Density Ratio of cell energy to weight or volume (watt-hours per pound, or watt-hours per cubic inch).

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Final Voltage (see Cutoff voltage)
Float Charging Method of recharging in which a secondary cell is continuously connected to a constant-voltage supply that maintains the cell in fully charged condition. Typically applied to lead acid batteries.