Lead-Acid Storage Batteries
DOE-HDBK-1084-95
DEFINITIONS
Rev. 0
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Batteries
Float charge
- 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.
Gassing
- Evolution of gas from one or more electrodes resulting from
electrolysis of water during charge or from self-discharge.
Significant gassing occurs when the battery is nearing the fully
charged state while recharging or when the battery is on
equalizing charge.
Potential difference
- Work which must be done against electrical forces to move a
unit charge from one point to the other, also known as
electromotive force (EMF).
Primary cell or battery
- Cell or battery which is not intended to be recharged and is
discarded when the cell or battery has delivered its useful
capacity.
Secondary battery
- A battery that after discharge may be restored to its charged
state by passage of an electrical current through the cell in the
opposite direction to that of discharge. (Also called storage or
rechargeable.)
Separator
- Electrically insulating layer of material which physically separates
electrodes of opposite polarity. Separators must be permeable to
ions in the electrolyte and may also have the function of storing
or immobilizing the electrolyte.
Specific gravity
- Ratio of the weight of a solution to an equal volume of water at
a specified temperature. Used as an indicator of the state of
charge of a cell or battery.
Sulfation
- Formation of lead sulfate crystals on the plates of a lead-acid
battery.
Terminal
- External electric connections of a cell or battery, also referred to
as "terminal post" or "post."
Thermal runaway
- A condition that occurs in a battery (especially valve-regulated
types) when charging energy results in heat generation within the
battery greater than the heat dissipated, causing an uncontrolled
rise in battery temperature. This can cause failure through cell
dry-out, shortened life, and/or melting of the battery.
