used in this website refers to sulphuric acid (H2SO4),
the active component of the electrolyte, or a mixture of sulphuric acid and
The active portion of the battery plates; peroxide of
lead on the positives and spongy metallic lead on the negatives.
Absorptive Glass Mat or
Starved electrolyte technology. This denoted a type of sealed lead acid
As used in battery construction is a homogeneous
combination of lead and other suitable ingredients.
The unit of measure of the rate of flow of electric
current. One amp flowing at the pressure of one volt equals one watt.
The product resulting from multiplication of amperes
flowing by time of flow in hours, e.g., a battery supplying 10 amperes for 8
hours gives 80 ampere hours. See note under "Volt?' for more complete
explanation of current flow.
Two or more electrical cells electrically connected in
series so that combination furnishes current as a unit.
The battery terminals are the means to access the
stored electrical energy in the battery. There is a minimum of one positive and
one negative terminal.
The number of ampere hours a battery can supply at a
given rate of current flow after being fully charged, e.g., a battery may be
capable of supplying 10 amperes of current for 8 hours before it is exhausted.
Its capacity is 80 ampere hours at the 8 hours rate of current flow. It is
necessary to state the. rate of flow, since same battery if discharged at 20
amperes would not last for 4 hours but for a shorter period, say 3 hours.
Hence, its capacity at the 3 hour rate would be (3 x 2O = 60) ampere hours.
The container in which the battery cells are housed.
The battery unit, consisting of an element complete
with electrolyte, in its jar with cover. Lead acid battery cells are nominally
2-volts. Two volts is the minimum nominal voltage for a lead acid cell.
Passing direct current through a battery in the
direction opposite to that of discharge, in order to put back the energy used
The proper rate of current to use in charging a
battery from an outside source. It is expressed in amperes and varies for
different sized cells.
The attack of metal parts by acid from the
electrolyte; it is the result of lack of cleanliness.
The cover forms a lid on each individual cell. It is usually
tongue and groove flange for a more effective seal.
One charge and discharge.
The flow of current from a battery through a circuit,
opposite of "charge."
The current flow measurement for discharge or charge
of a battery rated in Amps.
Term frequently applied to cell containing
insufficient electrolyte. Also applied to certain conditions of shipment of
The conducting fluid of electro-chemical devices; for
lead-acid storage batteries it consists of about two parts of water to one of
chemically pure sulphuric acid, by weight.
Positive group, negative group and separators.
The result of circulation and diffusion within the
cell which accompanies charge and discharge. Difference in capacity at various
rates is caused by the time required for this feature.
Term used to describe the making uniform of varying
specific gravities in different cells of the same battery, by adding or
removing water or electrolyte.
Loss of water from electrolyte from heat or charging.
The current in amperes at which a battery may be
charged for twenty-four hours or more. Also the charging rate used near the end
of a charge when cells begin to gas.
Electro-chemical process of making pasted grid or
other plate, types into storage battery plates.
A charge given to a battery which has been standing
idle, to keep it fully charged.
The giving off of oxygen gas at positive plates and
hydrogen at negatives, which begins when charge is something more than half
completed-depending on the rate.
See "specific gravity”.
The metal framework of a plate, supporting the active
material and provided with a lug for conducting the current and for attachment
to the strap.
A set of plates, either positive or negative, joined
to a strap. Groups do not include separators.
A glass barrel enclosing a hydrometer and provided
with a rubber bulb for drawing up electrolyte.
JAR See “Case”.
A term used to describe the operation of joining two
pieces of lead by melting them at practically the same instant so they may run
together as one continuous piece. Usually done with mixture of oxygen and acetylene
gases or LPG and oxygen gases. This process is used to join the plates to the
bus-bar and the bus-bar to the terminals. It is also used to connect cell to
cell in some applications.
The extension from the top frame of each plate,
connecting the plate to the strap.
The highest specific gravity which the electrolyte
will reach by continued charging, indicating that no acid remains in the
Loosened or worn out particles of active material
fallen to the bottom of cells, sometimes referred to as sediment.
The terminal of a source of electrical energy as a
cell, battery or generator through which current returns to complete circuit.
Generally marked "Neg".
The unit of electrical resistance. The smaller the
wire conductor the greater is the resistance. Six hundred and sixty-five feet
of No. 14 wire (size used in house lighting circuit) offers I ohm resistance to
The carrying of discharge beyond proper cell voltage;
shortens life if carried far enough and done frequently.
The mixture of lead oxide or spongy lead and other
substances which is put into grids.
The combination of the cast alloy grid, pasted with
active material of lead oxide, sulphuric acid and other ingredients. The positive
plate reddish brown and negatives slate gray.
POLARITY An electrical condition. The positive terminal (or pole) of a cell or
battery or electrical circuit is said to have positive polarity; the negative and negative polarity.
POSITIVE Generally marked "Pos" or + on top of the
battery next to the terminal. This denoted positive polarity.
The battery post is what delivers the electrical
energy from the internal bus-bar to the outside terminal. This is usually cast
from lead alloy.
Potential difference is the difference in voltage levels between
two sources. If a battery charger connected to a battery has a higher voltage
than the battery then current will flow into the battery from the charger.
RAPS Remote Area Power Supply.
This is the capacity in ampere hours of a given size
battery when discharged to a safe voltage.
Apparatus for converting alternating current into
direct current. Also called a battery charger.
Material (usually lamps or wire) of low conductivity
inserted in a circuit to retard the flow of current. By varying the resistance,
the amount of current can be regulated. Also the property of an electrical
circuit whereby the flow of current is impeded. Resistance is measured in ohms.
Analogous to the impediment offered by wall of a pipe to flow of water therein.
An electrical appliance used to raise or lower the
resistance of a circuit and correspondingly to decrease or increase the current
Reversal of polarity of cell or battery, due to
excessive discharge, or charging in the wrong direction.
Loosened or worn out particles of active material
fallen to the bottom of cells; frequently called' "mud".
That part of jar between bottom of the plates and top
of container bridge.
An insulator between plates of opposite polarity;
usually of wood, rubber or combination of both. Separators are generally
corrugated or ribbed to insure proper distance between plates and to avoid too
great displacement of electrolyte.
A metallic connection between the positive and
negative plates within a cell. The plates may be in actual contact or material
may lodge and bridge across. If the separators are in good condition, a short
circuit is unlikely to occur.
The density of the electrolyte compared to water as a
standard. It indicates the strength and is measured by the hydrometer.
Common term for lead sulphate. (PbSO4).
Term used to describe cells in an under-charged
condition, from either over- discharging without corresponding long charges or
from standing idle some time and being self discharged.
Forming lead sulphate on the surface of the positive
plate is a natural part of lead acid battery operation however this needs to be
reconverted by the charge phase of the battery. If the battery is not fully
charged then this lead sulphate can harden and crystalize. This blocks off part
of the plate and locks up the acid needed in the electrolyte for battery
operation. This will result in loss of capacity and if not corrected permanent
damage to the battery.
Part to which outside wires are connected.
UPS Uninterrupted Power Supply.
VENT, VENT PLUG OR VENT-CAP
Hard or soft rubber part inserted in cover to retain
atmospheric pressure within the cell, while preventing loss of electrolyte from
spray. It allows gases formed in the cell to escape, prevents electrolyte from
spilling, and keeps dirt out of the cell.
The commercial unit of pressure in an electric
circuit.Voltage is measured by a voltmeter. Analogous to pressure or head of
water flow through pipes. NOTE. - Just as increase of pressure causes more
volume of water to flow through a given pipe so increase of voltage (by putting
more cells in circuit) will cause more amperes of current to flow in same
circuit. Decreasing size of pipes is increasing resistance and decreases flow
of water, so also introduction of resistance in an electrical circuit decreases
current flow with a given voltage or pressure.
The commercial unit of electrical power, and is the
product of voltage of circuit by amperes flowing. One ampere flowing under
pressure of one volt represents one watt of power.
The unit of electrical work. It is the product of
power expended by time of expenditure, e.g., 10 amperes flowing under 32 volts
pressure for 8 hours gives 2560 watt hours.