Acid: Refers to sulphuric acid(H2SO4), or a mixture of sulphuric acid and water - the active component of the electrolyte.
Active Material: Indicates the active portion of the battery plates; peroxide of lead on the positives and spongy metallic lead on the negative.
Alternating Current: Electric current, which unlike direct current, rapidly reverses its direction or "alternates" in polarity so that it doesn’t charge a battery.
Ampere: The unit that measures the rate of flow of electric current.
Ampere Hour: It is the amount of energy charge in a battery that will allow one ampere of current to flow for one hour.
Battery: A device that comprises a group of electric cells that converts chemical energy into electrical energy to act as a source of direct current
Buckling: Warping or bending of the battery plates.
Capacity: The number of ampere-hours that a battery can supply at a given rate of current flow after being fully charged. e.g., a battery may be capable of supplying 8 amperes of current for 10 hours before it is exhausted. Its capacity is 80-ampere hours at the 10 hours rate of current flow. It is necessary to state the rate of flow, since same battery if discharged at 20 amperes would not last for 4 hours but for a shorter period, say 3 hours. Hence, its capacity at the 3 hour rate would be 3x20=60 ampere hours.
Case: The container that holds the battery cells.
Cell: The battery unit that comprises an element complete with electrolyte.
Charge: Passing direct current through a battery in the direction opposite to that of discharge, in order to restore the energy used on discharge.
Charge Rate: The rate of current that is required for charging a battery from an external source. The rate is measured in amperes and varies for cells of different size.
Corrosion: It is the erosion of metal parts on exposure by acid from the electrolyte.
Cycle: One discharge and charge.
Density: Specific gravity
Discharge: The flow of current from a battery through a circuit, opposite of "charge."
Dry: Term frequently applied to cell containing insufficient electrolyte. Also applied to certain conditions of shipment of batteries(i.e. without electrolyte)
Electrolyte: The conducting fluid of electro-chemical devices(for lead-acid storage batteries electrolyte comprises about two parts of water to one part of chemically pure sulphuric acid, by weight)
Element: Positive group, negative group and separators.
Evaporation: Loss of water from electrolyte due to heat or charging.
Filling Plug: The plug that fits in and closes the orifice of the filling hollow in the cell cover.
Freshening Charge: A charge given to an idle battery to keep it fully charged.
Gassing: Emission of oxygen at the positive plates and hydrogen at negatives, which begins when charge is nearing completion.
Gravity: A contraction of the term "specific gravity, " which means the density compared to water as a standard.
Grid: The metal framework of a plate that supports the active material and is provided with a lug for conducting the current.
Group: A set of plates, either positive or negative, joined to a strap. Groups do not include separators.
Hold-Down: Device to keep separators in place.
Hold-Down Clips: Brackets for the attachment of bolts for holding the battery securely in position within the car.
Hydrometer: An instrument for measuring the specific gravity of the electrolyte.
Hydrometer Syringe: A glass barrel enclosing a hydrometer and provided with a rubber bulb for drawing up electrolyte.
Lug: The extension from the top frame of each plate, connecting the plate to the strap.
Maximum Gravity: The highest specific gravity to which the electrolyte will reach by continued charging, indicating that no acid remains in the plates.
Negative: The terminal of a source of electrical energy as a cell, battery or generator through which current returns to complete circuit. Generally marked "Neg."
Over-Discharge: The carrying of discharge beyond proper cell voltage; this activity shortens battery life, if carried far beyond proper cell voltage and done frequently.
Paste: The mixture of lead oxide or spongy lead and other substances, which is put into grids.
Plate: The combination of properly "formed" grid and paste. Positive are reddish brown and negatives slate gray.