Battery Terminology

Understand the terminology used in battery purchase and usage. This glossary provides a solid foundation for understanding key battery-related terms.

  • Acid: Refers to sulfuric acid (H2SO4) or a mixture of sulfuric acid and water, which forms the active component of the electrolyte.
  • Active Material: The material on battery plates that participates in the chemical reaction; lead peroxide on positive plates and spongy metallic lead on negative plates.
  • Alternating Current (AC): Electrical current that reverses direction periodically, unlike direct current (DC), and does not charge a battery.
  • Ampere (Amp): A unit measuring the rate of electrical current flow.
  • Ampere Hour (Ah): The charge capacity of a battery, defined as the ability to supply one ampere of current for one hour.
  • Battery: A device consisting of multiple electrical cells that convert chemical energy into electrical energy.
  • Buckling: The warping or bending of battery plates, often due to excessive discharge or overcharging.
  • Capacity: The total ampere-hours a battery can deliver under a specified current flow before depletion.
  • Case: The outer container that holds the battery cells and protects internal components.
  • Cell: A single unit within a battery that contains electrodes and electrolyte, generating electrical energy.
  • Charge: The process of restoring energy to a battery by passing direct current through it.
  • Charge Rate: The speed at which a battery is charged, measured in amperes.
  • Corrosion: The deterioration of metal parts due to exposure to acid from the electrolyte.
  • Cycle: A full charge and discharge process.
  • Density: Also referred to as specific gravity, indicating the concentration of electrolyte.
  • Discharge: The process of supplying electrical current from a battery to a circuit.
  • Dry: A condition where a battery lacks sufficient electrolyte or is shipped without it.
  • Electrolyte: The conductive liquid in a battery (usually a mix of sulfuric acid and water) that enables electrochemical reactions.
  • Element: The combination of positive and negative plates along with separators within a cell.
  • Evaporation: The loss of water from the electrolyte due to heat or charging.
  • Filling Plug: A cap that seals the cell openings where electrolyte is added.
  • Freshening Charge: A maintenance charge given to idle batteries to keep them fully charged.
  • Gassing: The emission of hydrogen and oxygen gases from the battery plates during charging.
  • Gravity: A shorthand term for specific gravity, measuring electrolyte density.
  • Grid: The metal framework within a plate that holds active material and conducts current.
  • Group: A set of connected battery plates of the same polarity.
  • Hold-Down: A mechanism that secures separators in place.
  • Hold-Down Clips: Brackets used to fasten the battery securely in place within a vehicle.
  • Hydrometer: A tool used to measure the specific gravity of the electrolyte.
  • Hydrometer Syringe: A device with a glass barrel and rubber bulb used to draw electrolyte for gravity measurement.
  • Lug: A protruding part of the plate grid that connects to a strap, conducting electricity.
  • Maximum Gravity: The highest specific gravity reached by the electrolyte during full charge.
  • Negative Terminal: The battery terminal through which current exits to complete a circuit, marked “Neg.”
  • Over-Discharge: Excessive discharge of a battery beyond its recommended voltage, reducing lifespan.
  • Paste: A mix of lead oxide or spongy lead applied to battery grids to form plates.
  • Plate: A battery component made of a grid coated with active material, appearing reddish-brown for positives and slate-gray for negatives.
  • Polarity: The electrical orientation of battery terminals; the positive terminal supplies current, while the negative terminal completes the circuit.
  • Positive Terminal: The battery terminal from which current flows, marked “Pos.”
  • Post: The portion of the strap extending through the battery cover, used for external connections.
  • Potential Difference (Voltage): The electrical pressure that drives current through a circuit.
  • Rate: The amount of current, in amperes, used for charging or discharging a battery over a specific time.
  • Reversal: A condition where the polarity of a cell reverses due to excessive discharge or incorrect charging.
  • Separator: An insulating material between positive and negative plates, preventing short circuits while allowing ion flow.
  • Short Circuit: A low-resistance connection between two points in a circuit, causing unintended current flow and possible damage.
  • Specific Gravity: A measure of the electrolyte’s density compared to water, indicating battery charge level.
  • Strap: A lead casting that connects multiple plates within a group.
  • Sulfate: A common term for lead sulfate (PbSO4), a compound formed during battery discharge.
  • Sulfated: A battery condition where lead sulfate accumulates excessively due to prolonged discharge or lack of charging.
  • Terminal: The external connection points of a battery, linking it to a circuit.
  • Vent Plug (Vent Cap): A cap that maintains pressure balance within the cell, allowing gas release while preventing electrolyte loss.
  • Volt: The unit of electrical pressure that drives current through a circuit. Voltage is measured with a voltmeter.

This glossary provides a solid foundation for understanding key battery-related terms. Let us know if you need further clarification!

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