.AGM (Absorbed Glass Mat) - a lead-acid battery that incorporates a sponge glass mat separator to immobilize the electrolyte. Because of the immobilized electrolyte (acid), AGM batteries will not leak or spill. 

AMPERE (Amp.)- The ampere is a unit of measurement for current flow through a conductor or circuit. 

AMPERE-HOUR (Amp-hr or AH)- A unit of measurement for battery capacity obtained by multiplying the current flow in amperes by the time of the discharge in hours. Amp-hrs can also be used to help determine the proper charge rate for a battery. The amp-hr rating for an automotive battery is usually based on a 20hr discharge at 80° F, at a particular rate (determined by the amount of active material within the battery), until a minimum voltage of 1.75V/cell (10.5 volts for a 12 volt battery) is reached.  For example, if a 12 volt battery at 80° F delivers 4 amps for 20 hours before its voltage drops below 10.5 volts, its amp-hr capacity will be 4 amperes x 20 hours= 80 ampere-hours. 

BCI GROUP NUMBER- The BCI Group Number defines a battery by describing the following characteristics:     A.) Its maximum dimensions (L x W x H)      B.) Voltage (6 volt or 12 volt)     

C.) Post configuration      D.) The type of terminal used (top, side, flag, etc.)  It should be noted that the BCI (Battery Council International) Group Number does not designate a battery's capacity, it merely defines the above listed physical characteristics. 

CELL- A cell is the basic current producing unit of a battery. A cell consists of an element and electrolyte placed in a container and subsequently electrically formed. The standard full charged lead-acid battery will have 2.1 volts per cell or higher.Cell voltage is not dependent upon element size, but cell capacity is dependent upon element size. For example, a 10 plate cell and a 15 plate cell will both have 2.1 volts, but the 15 plate cell will have a higher capacity than the 10 plate cell. 

CIRCUIT - An electric circuit is the path through which amperes (current) flow.1.)  Open Circuit- has a broken or interrupted path and the current cannot flow. For example: the ignition key of a car is in the "off" position.  2.)Closed Circuit- has a complete path and the current can flow. For example: the ignition key is "on." 

COLD CRANKING AMPS (CCA)- The cold-crank rating is the primary rating presently used for automotive batteries. CCA's are the number of amperes a battery can deliver for 30 seconds at 0° F and still maintain a minimum voltage of 1.2 volts per cell (7.2 volts for a 12 volt battery). 

CURRENT- Current is defined as the flow of electricity through a conductor. The unit used to measure current is the ampere. Electrical current is found in two types: Alternating and Direct current. A.)Alternating Current (AC)- a current that reverses its direction at regularly recurring intervals. Alternating current is the standard household current in the United States.  

B.)Direct Current (DC)- An electric current that flows in one direction only.A battery delivers direct current and must be recharged with direct current. A battery charger "rectifies" the alternating current from a standard wall outlet into direct current to recharge the battery. 

CYCLE- In a battery, a discharge of any depth and a recharge. 

DEEP CYCLE BATTERIES- Batteries that are designed to withstand repetitive deep discharging and continue to provide their rated capacity even after hundreds of cycles. They are primarily used in Marine/RV applications.

DISCHARGE- When a battery is delivering power, it is said to be discharging. 

ELECTROLYTE- In a lead-acid battery, the electrolyte is sulfuric acid diluted with water. The approximate volume proportion of sulfuric acid to water in a fully charged liquid electrolyte battery is 25% sulfuric acid and 75% water (1.265 specific gravity). A lead-acid battery may have a liquid, gelled or immobilized electrolyte. The electrolyte is a conductor and plays a key role in the chemical reaction that produces the electricity required to crank an engine.

ELEMENT- A set of alternating positive and negative plates with a separator in between each plate.

FORMING- An electrochemical process in battery manufacturing that changes the lead oxide on the positive plates to lead peroxide (or lead dioxide) and the lead oxide on the negative plates to metallic lead (sometimes referred to as "sponge lead").

GRID- A lead alloy framework that supports the active material of a battery plate (lead peroxide/dioxide or metallic lead) 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 cable, to the body, frame or engine block of the car which is used as a path for completing a circuit in lieu of a direct wire from a component.

KILOVOLT (VA)- A unit of power equal to 1,000 volts x Amperes. Kilovolt Amps are used to define UPS (Uninterrupted Power Supply) system capacities.

KILOWATT (KW)- A unit of power equal to 1,000 watts. Kilowatts are used to define a battery's capacity as a function of watts (see Watt).

LOAD TESTER- An instrument that measures battery voltage when an electrical load (discharge) is applied to the battery. Based on the load, discharge time, and the battery's voltage during the load test, one can determine the overall condition of the battery and its ability to perform under engine starting conditions.

LOW WATER LOSS BATTERY- A battery which does not require periodic water addition under normal service conditions. Interstate Batteries are a "low water loss" design. 

OHM- A unit used in electricity for measuring the resistance to current flow. Resistance to current flow manifests itself in the form of heat energy. 

OHM'S LAW- An equation that expresses the relationship between Volts, Amps., and Ohms in an electrical circuit. This equation is expressed as:Volts (E) = Amps (I) x Ohms (R) 

OPEN CIRCUIT VOLTAGE- The 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. 

PARALLEL CIRCUIT- A circuit in which the current has more than one path to follow. In a parallel circuit, the positive post of the first battery is connected to the positive post of the second battery, and the negative post of the first battery is connected to the negative post of the second battery, etc. The voltage of a parallel circuit does not change with the addition of more batteries, but the capacity is the sum of all of the batteries in the parallel circuit. For example: Using four 12 volt, 80 amp-hr. batteries in a parallel circuit would still be 12 volts, but the capacity of the circuit would be 320 amp-hr (80 amp-hr x 4 batteries = 320 amp-hr).

PRIMARY BATTERY- A battery that cannot be recharged, e.g., a dry-cell flashlight battery. 

RESERVE CAPACITY RATING- The time in minutes that the battery will deliver 25 amps at 80° F until it falls below 1.75 volts per cell (10.5 volts for a 12 volt battery). This rating represents the time the battery will continue to operate essential accessories during night driving if the alternator or generator fails.

SECONDARY BATTERY- A battery that can be recharged by passing direct current through the battery in a direction opposite to that of discharge. The automotive lead-acid battery is a secondary battery.

SERIES CIRCUIT- A circuit in which the current has only one path to follow. In a series circuit, the positive post of the battery is connected to the negative post of the second; the positive post of the second battery is connected to the negative post of the third battery, etc. The voltage of a series circuit is the sum of the voltages of all batteries hooked together in the series, but the capacities of the system is the same as the smallest battery in the circuit. For example: If there are four 12 volt, 80 amp-hr. batteries hooked together in a series, the voltage of this circuit would be 48 volts (12 x 4 = 48). The capacity of this circuit, however, would still be 80 amp-hr.

VOLTS- A unit for measuring electrical pressure. It is the amount of "push" amps receive in an electrical circuit.

WATT- A unit for measuring electrical power. Watt = Amps x Volts.