2WD2-Wheel Drive
4WD4-Wheel Drive
ACAir Conditioning
AcidA type of chemical that can release hydrogen ions when mixed with water. Sulfuric acid is used in a lead-acid battery.
AGMAbsorbent Glass Mat (AGM) is a type of non-woven separator material comprised almost entirely of glass microfibre that absorbs and retains the electrolyte, leaving no free electrolyte in the cell to spill. VRLA batteries made with this material are often referred to as “AGM” batteries.
AGM BatteryA lead acid battery with electrolyte immobilized in the active material and absorbent glass mat separator material. The AGM battery is sealed under normal conditions, but allows gaseous products to escape through a pressure controlled valve. An AGM typically has significantly improved cycling capability and charge recovery compared to standard flooded Starter batteries. 
Ampere (amp) Ampere is a unit of measure for current flow through a conductor or circuit.
Ampere-hour (Ah)The unit of measure for a battery’s electrical storage (Ah) capacity, obtained by multiplying the current flowing amperes by the time in hours of the discharge. Example: A battery that delivers 5 amperes for 20 hours delivers 5 amperes × 20 hours = 100 Ah of capacity.
AT or Auto. Trans.Automatic Transmission
ATVAll-Terrain Vehicle
BatteryOne or more galvanic (electrochemical) cells electrically coupled into a single unit and equipped with attachments for external electrical connections.
Battery ChargerA device capable of supplying electrical energy to a battery.
BCIBattery Council International
BCI Group NumberThe BCI group number “fingerprints” a battery with the following characteristics: (a) dimensions (L x W x H), (b) voltage (6V or 12V), (c) polarity (right hand front positive, left hand front positive, etc.), (d) type terminals (top, side, “L,” etc.). The BCI group number does not designate a battery’s capacity, it merely defines the above-listed physical characteristics.
Boost ChargeThe process of ensuring that the cells and plates within a battery are charged sufficiently for the battery to perform its desired function. Boost charging is typically done for a short duration at a high current. 
CACranking Amps
CapacityThe capacity of a battery is a measure of the amount of energy that it can deliver in a single discharge.
ccCubic Centimetres
CCA (Cold Cranking Amps) Cold cranking amps is a rating used in the battery industry to define a battery’s ability to start an engine in cold temperatures. A large amount of amperes are needed to start the engine, but only for a short period of time. The actual rating is the number of amps that can be removed from a new, fully-charged battery at -17 °C (0°F) for 30 seconds while maintaining a voltage of at least 7.2 volts (for a 12-volt battery). The higher the CCA rating, the greater the starting power of the battery.
CellThe basic electrochemical current-producing unit in a battery, consisting of a set of positive plates, negative plates, electrolyte, separators and casing. In a lead-acid battery, the cell has an open-circuit voltage of approximately 2 volts. There are six cells in a 12-volt lead-acid battery.
CFICentral Fuel Injection
CorrosionThe chemical or electrochemical reaction between a material, usually a metal, and its environment that produces a deterioration of the material and its properties. The positive lead grids in a battery gradually corrode in service, often leading to battery failure. Battery terminals are subject to corrosion if they are not properly maintained.
Current The flow of electricity, or electrons (as produced during the discharge of a battery), through a conductor. The unit used to measure current is the ampere. There are two types of electrical current: Alternating current (AC) is a current that varies periodically in magnitude and direction. Standard household current in the U.S. is alternating current. Direct current (DC) is an electric current flow in one direction only. A battery delivers direct current and must be recharged with direct current. A battery charger “rectifies” the alternating current it receives from a standard wall outlet into direct current that is then delivered to the battery. Most European countries use direct current as their electric power source.
Cycle In a battery, a cycle consists of a discharge followed by a recharge. Automotive batteries are not normally cycled; marine and RV batteries, however, are, and they are specially designed to undergo repetitive cycling.
Deep Cycle A battery that provides a steady amount of current over a long period of time provides a surge when needed and is designed to be deeply discharged over and over again. Deep-cycle batteries are designed to withstand these rated repetitive cycles and still continue to provide their capacity after hundreds of cycles.
Discharge When a battery is delivering power, it is said to be discharging.
DOHCDual Overhead Cam
DTDual Terminal
EFIElectronic Fuel Injection
Electrolyte The automotive starting-lighting-ignition (SLI) battery is commonly referred to as a “lead-acid” battery. The acid, often called electrolyte, is a mixture of sulfuric acid and water. The approximate volume proportion of sulfuric acid to water in a fully charged battery (1,265 specific gravity) is 25 percent sulfuric acid and 75 percent water. The electrolyte plays a key role in the chemical reaction that begins when the ignition switch of a car is turned on. This reaction produces the electricity required to crank the engine.
Element A set of alternate positive and negative plates with a separating material (separator) between each plate.
ETRElectronic Tuning Radio
FIFuel Injection
Flooded BatteryA lead acid battery with free flowing electrolyte. The construction includes a cover with one or more vents through which gaseous products may escape. Commonly called an SLI (starting, lighting, ignition) or "Starter" battery.
Formation In battery manufacturing, formation is the process of charging the battery for the first time. Electrochemically, formation changes the lead oxide paste on the positive grids into lead dioxide and the lead oxide paste on the negative grids into metallic sponge lead.
FWDFront Wheel Drive
Gel Electrolyte that has been immobilized by the addition of a chemical agent, normally fine silica, to prevent spillage. Batteries made with gelled electrolyte are often referred to as gel batteries. Gel batteries are a type of VRLA battery. 
GMGeneral Motors
Grid A lead alloy framework (or skeleton) that supports the active material of a battery plate and is the primary conductor of electricity.
Ground The connection made in grounding a circuit. In automotive use, the result of attaching one battery cable (usually the negative) to the body, frame or engine block, which is used as a path for completing a circuit in lieu of a direct wire from a component.
Group SizeThe Battery Council International (BCI) assigns numbers and letters for common battery types. They are standards for maximum container size, location and type of terminal and special container features.
H.D.Heavy Duty
H.O.High Output
HBLHeated Backlight
HSCHigh Swirl Combustion
HydrometerA float instrument used to determine the state of charge of a battery by measuring the specific gravity of the electrolyte (i.e., the concentration of sulfuric acid in the electrolyte).
IHCInternational Harvester Co.
Intercell Connectors Lead structures that connect adjoining cells in a series, positive of one cell to the negative of the next, within a battery.
Lead-acid BatteryBattery made up of plates, lead and lead oxide with a 35% sulfuric acid and a 65% water solution. This solution is called electrolyte, and causes a chemical reaction that produces electrons. 
Load TesterAn instrument that measures battery voltage when an electrical load (discharge) is applied to the battery. Based on the load, discharge tie and the battery’s voltage, the tester can determine the overall condition of the battery and its ability to perform under engine starting conditions.
LPGLiquefied Petroleum Gas
Maintenance-free A battery that normally requires no service watering during its lifetime of use.
Marine Cranking Amps (MCA)MCA is an industry rating defining a marine battery’s ability to deliver a large amount of amperage for a short period of time. Since marine batteries are typically never used at temperatures below freezing, marine cranking amps are measured at 0 °C (32 °F) as opposed to -17 °C (0 °F) for cold cranking amps. The rating is the number of amps that can be removed from a marine battery at 0 °C (32 °F) for 30 seconds while maintaining a voltage of at least 7.2 volts for a 12-volt battery. The larger the MCA rating, the greater the starting power of the marine battery.
MT or Man. Trans.Manual Transmission
O.E.Original Equipment
O.E.S.Original Equipment Service
OHCOverhead Cam
Ohm A unit for measuring electrical resistance or impedance within an electrical circuit. Resistance to current flow manifests itself in the form of heat energy.
Ohm’s LawExpresses the relationship between volts (V) and amperes (A) in an electrical circuit with resistance (R). It can be expressed as follows: V=IR. Volts (V) = amperes (I) x ohms (R). If any two of the three values are known, the third value can be calculated using the equation.
OHVOverhead Valve
Open-circuit VoltageThe voltage of a battery when it is not delivering or receiving power. Open-circuit voltage is one of the primary methods of determining a battery’s state of charge.
OptionalThis designation shows that a higher capacity battery was available as original equipment at extra cost in the model on the previous line. It may show that higher capacity in the same group size was available or that a larger group size battery will fit the battery tray and holddown.
PlatesThin, flat structures comprised of a grid and active material. The grid supports the active material and conducts electrons out of the cell. Plates are either positive or negative, depending on the active material they hold.
PSPower Steering
PWCPersonal WaterCraft
RCReserve Capacity
Reserve Capacity and Rating The time in minutes that a new, fully charged battery will deliver 25 amperes at 27 °C (80 °F) and maintain a terminal voltage equal to or higher than 1.75 volts per cell. This rating represents the time the battery will continue to operate essential accessories if the alternator or generator of a vehicle fails.
Resistance The opposition to the free flow of current in a circuit or battery. It is commonly measured in ohms.
RWDRear Wheel Drive
SEOSpecial Electrical Option
Separator A porous divider between the positive and negative plates in a cell that allows the flow of current to pass through it. Separators are made from numerous materials such as polyethylene, polyvinyl chloride, rubber, glass fibre and cellulose.
SHOSuper High Output
Short Circuit An unintended current-bypass in an electric device or wiring, generally very low in resistance and thus causing a large current to flow. In a battery, a cell short circuit may be permanent enough to discharge the cell.
SLI batteryStarting, Lighting and Ignition battery, or a Flooded battery.  
SOHCSingle Overhead Cam
Specific Gravity The density of a liquid compared with water density. The specific gravity of the electrolyte is the weight of the electrolyte compared to the weight of an equal volume of pure water.
State of Charge The amount of electrical energy stored in a battery at a given time expressed as a percentage of the energy when fully charged.
Stratification The unequal concentration of electrolyte due to density gradients from the bottom to the top of a cell.
TBIThrottle Body Injection
Terminals The electrical structures on the battery to which the external circuit is connected. Typically, batteries have either top-terminals (posts) or side-terminals. Some batteries have both types of terminals (dual-terminal). 
Top T.Top Terminal
Valve Regulated Lead Acid Battery (VRLA) AGM and Gel are the two types of VRLA batteries. These batteries have no “free” liquid electrolyte and in the cell operate on the oxygen recombination cycle, which is designed to minimize water loss. 
Vents Mechanisms that allow gases to escape from the battery while retaining the electrolyte within the case. Flame-arresting vents typically contain porous disks that reduce the probability of an internal explosion as a result of an external spark. Vents come in both permanently fixed and removable designs.
Voltmeter An electronic device used to measure voltage, normally in a digital format.
Volts A unit in electricity for measuring electrical pressure or the amount of “push” amperes receive in an electrical circuit.
Watt The unit for measuring electrical energy or work. Watts = amperes × volts.