Active Material - In the positive plates, the active material is lead dioxide. IN the negative, it's metallic sponge lead. When a circuit is created, these materials react with sulfuric acid during charging and discharging.

Ampere (Amp) - A unit of measurement for the electron flow or current through a circuit.

Ampere-Hour (Amp. Hr., AH) - A unit of measure for a battery's electrical storage capacity, calculated by multiplying the current in amperes by the time in hours. (Example: A battery which delivers 5 amps for 20 hours provides 5 amps x 20 hours = 100 AH of capacity.)

Battery - The unit for storing chemical energy and converting and discharging this energy as electrical current.

Capacity - The Number of ampere-hours (Ah) a fully charged cell or battery can carry under certain conditions of discharge.

Cell - The basic current-producing unit in a battery. It consists of a set of positive plates, negative plates, electrolyte, separators and casing. A cell's nominal voltage is 2 volts. (Example: A 12-volt battery has 6 cells).

Charge - The process of restoring electrical energy to a cell or battery.

Circuit - The path followed by a flow of electrons. A closed, or short, circuit is a complete path. An open circuit has a broken path.

Container - Polypropylene or hard rubber case. It holds the battery plates, straps and electrolyte.

Corrosion - Damaging chemical reaction of a liquid electrolyte with a reactive material.

Cycle - One discharge of a battery plus one recharge.

Cycle Life - The number of cycles a cell or battery provides before failure.

Cycle Use - A method of using a secondary battery repeatedly by charging and discharging.

Deep Discharge - The state in which a cell is fully discharged using low current, so that the voltage drops below the final discharging voltage.

Depth of Discharge (DOD) - The percentage of capacity actually removed from a battery compared to the total rated capacity.

Discharge - The process of battery current delivering.

Electrode - A conducting mass that includes materials, which are capable of reacting with the electrolyte in a cell to produce or accept current.

Electrolysis - The electrochemical decomposition of water from the electrolyte.

Electrolyte - In a deep cycle battery, it is a dilute solution of sulfuric acid and water.

Equalization - An overcharge performed on flooded lead-acid batteries after they have been fully charged. This maintenance step helps eliminate stratification and sulfation.

Float charge - A Method of charging in which a secondary cell is continuously connected to a constant-voltage supply that maintains the cell in a fully charged condition.

Grid - The lead alloy framework that supports the active material of a battery plate and conducts current.

Hydrometer - A tool used to measure the specific gravity of the electrolyte solution.

Ohm (Ω) - A unit of measurement for electrical resistance within a circuit.

Open Circuit Voltage - The voltage of a battery when there is no load attached (not receiving or delivering energy). This measurement is best taken when the battery has been at rest for at least 6 hours.

Power Inverter - An electronic device that converts direct current (DC) power from a battery into standard alternating current (AC) house power.

Primary Battery - An energy storage device that can deliver energy but cannot be recharged (i.e., disposable flashlight battery).

Secondary Battery - An energy storage device that can deliver energy and can be recharged (i.e. automotive or deep cycle battery).

Separator - A divider made of porous material that is placed between the positive and negative plates in a battery cell and allows current to flow through it, while preventing direct contact between the plates that would cause a short circuit.

Specific Gravity (S.G.) - A measure of the strength of battery electrolyte by comparing its density to that of pure water.

Stratification - A condition where the concentration of acid is greater at the bottom of the battery than at the top.

Sulfation - The formation of lead sulfate on the positive and negative electrodes.

Volt (V) - A unit of measurement for electrical potential within a circuit.

Voltage - Electromotive force or potential difference, expressed in volts (V).

Watt (W) - A unit of measurement for electrical power.

Watt Hour (Wh) - A unit of measurement for electrical power for a certain period of time.