Alternating current; a flow of electrons, which regularly
reverses its direction of flow. 60 cycles per second is the US standard.
One cycle per second is called one Hertz (Hz). Because of how generators
work the switching of peak positive current to peak negative current takes
place gradually in a sine wave pattern. Cannot be stored like DC (Direct
Current) in a battery.
The taking up or retention of one material by another by chemical or
The liquid in a battery cell.
acid (H2SO4), is diluted with water (approx. 62%
water) to produce “electrolyte”, or
battery acid. Pure sulfuric
acid (93% acid) is far too concentrated and unstable for use in
batteries. Under normal circumstances, it is not necessary to add acid to a
battery, only water, to bring the electrolyte
to the proper
level in each cell to prevent it from drying the plates.
A term used to describe the lead
that is held in place by grids (plates)
that make up a battery cell.
This term usually refers to both the positive and negative plate
material. The material reacts chemically to produce electrical energy by
releasing free electrons. In an industrial battery, the materials are: lead
peroxide (positive) and sponge lead (negative). One active
material is oxidized while the other is reduced.
An inline fuse between the AC power supply and the charger. All
battery chargers are fused internally, in addition to external circuit
breakers or disconnects required by code. These fuse are usually rated at
600vac, but are available in 250vac for chargers designed with a maximum AC
voltage of 240vac. 250vac fuses are intentionally shorter than 600vac fuses
so that they cannot be substituted. The voltage rating of a fuse must
exceed the actual AC voltage or a fire hazard will result.
Making a dry cell
functional by adding electrolyte.
Absorbed glass mat.
A charged negative plate
that has been removed from electrolyte
and permitted to discharge
in an air atmosphere. Plates
must then be recharged before they are capable of producing useful
A mixture of metals or a metal and a non-metal.
A pulsating electric current in which direction of flow
is rapidly changed, so the terminal becomes in rapid succession positive,
then negative. Abbreviated AC.
A type of generator used in automobiles to produce electric current.
The average humidity of the surroundings.
The average temperature of the surroundings.
An instrument for measuring electrical current.
Current carrying capacity
The maximum amperage a given wire size can safely
The unit of electrical current equal to the steady state current produced
by one volt applied across a resistance
of one ohm. Or, a count of how many electrons pass a given point in one
second. A closed circuit is necessary for current flow.
The strength of an
electrical current expressed in amperes
A measure of the volume of electricity, being one ampere
for one hour. It is used to express battery
and is registered by an ampere-hour
meter; it can be obtained by multiplying the current in amperes
by length of time that the current is maintained. You can convert amp-hrs
to waft hours by multiplying amp-hrs by the systems battery voltage.
The quantity of electricity measured in ampere-hours (Ah)
that may be delivered by a cell
or battery under specified conditions.
efficiency of a storage battery expressed
as the ratio of ampere-hours
output to the ampere-hours
input required for recharge.
An instrument that registers the quantity of electricity in ampere-hours.
The electrode in an electrochemical
takes place. During discharge,
the negative electrode of the cell
is the anode. During charge, the positive electrode is the anode.
Antimonial Lead Alloy
A commonly used alloy in battery
castings. The percentage of antimony varies from 1/2% to 12%. Other
substances are present in small quantities, either as inescapable
impurities or by design to improve the properties of the cast part.
A hard, brittle, silver white metal with a high luster from the arsenic
1. Combining various parts into a finished battery.
2. Any particular arrangement of cells,
connectors and terminals to form a battery.
SLI battery of 3 or 6 cells
used for starting, lighting and ignition of cars, trucks, buses, etc.
A storage battery’s average value of voltage during a period of
charge or discharge.
Two or more electrochemical
electrically interconnected in an appropriate series/parallel
arrangement to provide the required operating voltage and current levels.
Under common usage, the term "battery"
is often also applied to a single cell
if it is used alone. A battery cell
contains an anode, a cathode, and the electrolyte. The nominal voltage of a
is 2 volts.
A cylindrical cell
design utilizing an internal cylindrical electrode and an external
electrode arranged as a sleeve inside the cell
The ribbed supporting structure in the bottom of a battery container that provides sediment space
the elements, thereby preventing short circuits.
Welding together two or more lead
or lead alloy parts such as plates,
straps, and connectors.
The center-to-center distance between adjacent plates
of the same polarity.
or lead alloy stick used as a supply of joining material in lead burning.
C-Rate (also see Hourly Rate)
or charge current, in amperes,
expressed in multiples of the rated capacity.
For example, C/10 discharge
current for a battery rated at 1.5 Ah
is: 1.5 AH/I
0 = 150 mA (A cell's
is not the same at all discharge
rates and usually increases with decreasing rate.)
A metallic element highly resistant to corrosion, used
as a protective plating on certain parts and fittings.
A third electrode for separate measurements of the
electrode potential of positive and negative plate
Calcium Lead Alloy
base alloy that is sometimes used for battery
parts in place of antimonial lead alloys.
The total number of active
material or watt-hours that can be withdrawn from a fully charged cell
or battery under specified conditions of discharge.
A correction factor applied to the rating of a battery
under different C-rates from the one rated.
Capacity Retention (or Charge Retention)
The fraction of the fall capacity
available from a battery under specified
conditions of discharge
after it has been stored for a period of time.
A test that discharges
the battery at constant current at room
temperature to a cutoff voltage of usually 1.70 volts/cell.
Forming a molten substance into a shape by introducing the material
into a mold and allowing it to solidify.
A metallic item, such as one or more grids, straps or connectors,
formed by pouring a molten substance into a mold and allowing it to
A multiple connector that had been cast onto the plates
directly in a combination mold/burning jig; contrasts with burning of plates
and prefabricated straps.
The electrode in an electrochemical
where reduction takes place. During discharge,
the positive electrode of the cell
is the cathode. During charge in a rechargeable battery,
the negative electrode is the cathode.
The basic electrochemical
unit used to generate or store electrical energy. One
2-volt unit connected in series
to create a battery.
within a battery pack that contain
and voltage levels.
The stronger cells
of a battery (several cells
connected in series)
impose a voltage of reverse polarity across a weaker cell
during a deep discharge.
Charge / Charging
The conversion of electrical energy, provided in the form of electrical
current from an external source, to restore the chemical energy in a cell
Technique for effectively terminating the charging of a rechargeable battery.
The amount of energy per unit of time, which is
being added to the battery. Commonly expressed as a ratio of the battery's
rated capacity to charge in relation to the time of charge duration. If you
have a battery with a storage capacity of 1,000 amp-hrs and your charger is
rated at 50 amps then your charge rate is expressed as C/20 (1,000 / 50 ).
A storage cell
at maximum ability to deliver current. The positive plates
contain a maximum of lead oxide and a minimum of lead sulfate, and the
contain a maximum of sponge lead and a minimum of sulfate, and the electrolyte
is at maximum specific gravity.
Charged and Dry
A battery assembled
with dry, charged plates
and no electrolyte.
Charged and Wet
A fully charged battery
and ready to deliver current.
The process of converting electrical energy to stored
chemical energy. In the lead-acid
battery, it converts lead sulfate in the plates
to lead peroxide (positive) or lead (negative).
The current, expressed in amperes,
at which a battery is charged.
A system of electrical components through which an
electric current is intended to flow. The continuous path of an electric
Closed-circuit Voltage (CCV)
The potential or voltage of a battery when
it is discharging or charging.
A process that utilizes a series of heavy discharges and recharges on a battery to assure optimum performance.
A battery discharge
regime whereby the current drawn during the discharge
Constant Current Charge
A charge that maintains the current at a constant value. For some types of
batteries this may involve two rates, called a starting and a finishing
Constant Potential Charge or Constant Voltage Charge
A charge that holds the voltage at the terminals at a
A battery discharge
regime whereby the current during the discharge
increases as the battery voltage
A battery discharge
regime whereby the resistance
of the equipment load remains constant throughout discharge.
A test in which a battery is discharged
to a prescribed end point voltage without interruption.
The amount of electricity transported by a current of one ampere
flowing for one second.
The lid of an enclosed cell,
generally made of the same material as the container and through which the
posts and vent plug extend.
or lead alloy rings molded or sealed into the cell
cover, and that the element posts are burned to, thereby creating an
Travel of electrolyte
up the surface of electrodes of other parts of the cell
above the level of the main body of the electrolyte.
Chemical conversion process that changes lead oxides and
acid to mixtures of basic lead sulfates, basic lead carbonates, etc.,
which consequently forms the desired structures of lead
or lead sulfate on negative and positive plates
The time rate of flow of electricity, normally expressed
like the flow of a stream of water.
An inert structure of high electrical conductivity used to conduct current
from or to an electrode during discharge
The current per unit active area of the surface of an electrode.
The current withdrawn from a battery
Current Limiting Chargers
A charger that keeps the charge current constant during the charge process
but allows the voltage to Fluctuate (typically used on NiCd and NiMh
The battery voltage at which the discharge
is terminated. The cutoff voltage is specified by the battery manufacturer and is generally a function
of discharge rate.
Cutting (of acid)
Dilution of solution of sulfuric
acid to a lower concentration, or “specific
A sequence where a charged battery is discharged
and recharged. One complete charge / discharge sequence of the battery.
Forklift batteries are rated to last for 1500 to 2000 cycles.
Cycle Life The number of cycles
under specified conditions that are available from a secondary battery before it fails to meet specified
criteria as to performance.
Battery operation that continuously
subjects a battery to successive cycles
of charge and discharge,
e.g., motive power service.
The positive and negative plates
are rolled up and placed into a cylindrical container (as opposed to
stacking the plates
in a prismatic cell
DC (Direct Current)
Direct current; a flow of
electrons that flows only in one direction, negative to positive. PV's
produce DC power. DC can be stored electrochemically in a battery.
Deep Cycle Battery
A battery specifically made to
have up to 80% of its energy capacity removed and replaced repeatedly for
of this type of battery are much thicker than are starting battery's plates.
Removal of up to 80% of the rated capacity
of a cell
Depth of Discharge (DOD)
The ratio of the quantity of electricity (usually in ampere-hours)
removed from a battery to its rated capacity.
The opposite of absorption, whereby the material retained by a medium or
another material is released.
An electric test performed on jars, containers and other
insulating materials to determine their dielectric breakdown strength.
The intermingling or distribution of particles or
molecules of a liquid.
A one-way check valve allowing electricity to flow in one
Electrical current that flows in one direction only. Batteries produce
direct current as the current flows from a negative to a positive source.
The conversion of the chemical energy of a battery
into electrical energy, and the withdrawal of the electrical energy into a
The rate, usually expressed in amperes,
at which electrical current is taken from the battery.
A storage cell
when, as a result of delivering current, the plates
are sulfated, the electrolyte
is exhausted, and there is little or no potential difference between the
The current withdrawn from a battery
with immobilized electrolyte.
The term "dry cell" is often used to describe the Leclanche cell.
that have been subjected to the dry charging process.
Manufacturing process in which tank-formed battery plates
are washed free of acid
and then dried.
Straight battery pack without internal
circuits enabling communication between the battery
and the user.
The operating regime of a battery
including factors such as charge and discharge
rates, depth of discharge,
duration, and length of time in the standby mode.
or charge power, in watts, expressed as a multiple of the rated capacity
of a cell
or battery that is expressed in
watt-hours. For example, the E/10 rate for a cell
or battery rated at 17.3 watt-hours is
1.73 watts. (This is similar to the method for calculating C-Rate.)
The ratio of the output of a cell
or battery to the input required to
restore the initial state of charge under specified conditions of
temperature, current rate and final voltage.
The movement of electrons along a conductor.
Weight of a substance that is deposited at an electrode when the quantity
of electricity which is passed is one coulomb
The site, area or location at which electrochemical
processes take place.
The difference in potential between the electrode and
the immediately adjacent electrolyte,
expressed in terms of some standard electrode potential difference.
reaction that causes the decomposition of a compound.
acid. The medium, which provides the ion transport (see ion) mechanism
between the positive and negative electrodes of a battery cell.
Electromotive Force (EMF)
The force that causes electrons to flow because of a difference in
electrical potential (measured in volts).
Negatively charged particle that orbits the nucleus of an atom. Electrons
have 1/1837 the mass of hydrogen (the lightest atom), and are subatomic.
An assembly of a positive plate
group, negative plate
group and separators.
The specific gravity of a cell
at the end of a prescribed discharge.
End Voltage Cutoff
The prescribed voltage at which the discharge (or charge, if end-of-charge voltage) of a battery may be considered complete.
The output capability of a cell
or battery, usually expressed in
The ratio of the energy available from a battery
to its volume (Wh/L) or weight (Wh/kg).
folded and wrapped around a battery plate
overcharge, or extended charge, that restores all cells
in a battery to 100% state of charge (SOC). Ensures complete
restoration of active
materials in all the plates
of the cells.
The controlled overcharge of a seemingly fully charged battery (many cells
within the battery already are fully charged) to bring the weaker cell
(s) up to full charge. Should be accomplished every 30 days, or as needed.
You can determine unequal cells
with a hydrometer
(should be within 15 points lowest to highest reading), or you can check
voltage readings across each cell
and compare them (should be within .05 volts lowest to highest readings
An ingredient in the negative paste
that delays shrinking and solidifying of the sponge lead of the finished plate,
thereby enhancing negative plate
The fast-charger detects the state of charge and switches to trickle charge
when full-charge is reached.
A constant volt power supply containing a special
transformer-capacitor combination that changes operating characteristics as
the draw is varied, ensuring that voltage output remains constant.
gravity of acid
used to fill batteries.
The cut-off voltage of a battery.
The prescribed voltage reached when the discharge
is considered complete.
The rate of charge, in amperes,
to which charging current is reduced near the end of the charge for some
types of batteries to prevent gassing and temperature rise.
Fixed Resistance Discharge
of a cell
or battery through a fixed resistive load,
the current being allowed to fall off as the terminal voltage decreases.
Float (Float Charge)
A low rate of charge that will maintain a battery
at a full SOC without over charging the battery. The use of
batteries in which they are charged by an application to be ready for use
if the primary power to the application fails. Also called standby or
Similar to trickle charge. Compensates for the self-discharge
on a SLA battery
A recharge at a very low rate, accomplished by
connection to a buss whose voltage is slightly higher than the open circuit
voltage of the battery.
Those where the electrodes/plates
are immersed in electrolyte. Since gases created during charging are vented
to the atmosphere, distilled water must be added occasionally to bring the
electrolyte back to its required level.
The most familiar example of a flooded lead-acid cell is the 12-V automobile battery.
Projections from the grid at the bottom edge, used to
support the plate
Discharging a cell
in a battery, by the other cells
or an external power source, below zero volts into voltage reversal.
Formation or Forming Charge
An initial charging process that electrochemically
converts the raw paste
of the plates
into charged active
material, lead peroxide in the positive plates
and sponge lead in the negative plates.
that have undergone formation.
A charge given batteries in storage to replace the standing loss and ensure
that every plate
is periodically brought up to full charge to prevent sulfation.
Full Charge Gravity
Specific gravity of the electrolyte
are fully charged and properly leveled.
Device used for cutting off an electrical current in the event of an
abusive condition. Also see AC Fuse.
The separation of hydrogen and oxygen that occurs
as the battery approaches 100% SOC. It can also happen if the battery is
under heavy load. This gas is very explosive when in concentrations of more
than 2 PPM (parts per million).
A device that produces an electric current through magnetism.
Fabric made from glass fibers with a polymeric binder
such as styrene or acrylic, which is used to help retain positive active
The ratio of the energy output of a cell
or battery to its weight (Wh/kg). This
term is used interchangeably with specific energy.
The number of point’s reduction or drop of specific
gravity of the electrolyte
A metallic framework used in a battery
for conducting electric current and supporting the active
material or active mass.
To connect to the earth or some conductor, which takes the place of the
One or more plates
of one type – positive or negative – burned to a post or strap.
Waste which is classified as "hazardous" (i.e.. potentially
harmful to the environment) by the government.
The standard unit of frequency. A frequency of one complete cycle per
second is a frequency of one hertz.
On charge, any rate higher than the normal finishing
A discharge rate, in amperes,
of a battery, which will deliver the
specified hours of service to a given cutoff voltage.
Reaction between water and lead
or lead compounds. Gravities lower than those found in discharged
are apt to produce hydration, which appears as a white coating on plate
groups and separators
in a cell.
A device used to measure the specific gravity of the electrolyte
in a cell.
Curing process for plates
that oxidize the lead paste,
reducing free lead to a few percent of total.
Impedance Intermittent Test
Used in terms of the battery's internal resistance
a test during which a battery is subjected
to alternate periods of discharge
and rest according to a specified discharge
The closed circuit voltage at the beginning of a discharge.
It is usually measured after current has flowed for a period sufficient for
the voltage rate of change to become practically constant.
A bushing of lead
or lead alloy molded or sealed into cell covers, and to which the post is
burned to create a creep-resistant, cover-to-post seal.
Conductor of lead
or lead alloy used to connect two battery cells.
The opposition exhibited by a circuit element (cell
or battery) to the flow of an alternating
current (a/c.) of a particular frequency as a result of resistance,
induction and capacitance.
Internal Resistance (IR)
The opposition exhibited by a circuit element to the flow of direct current
(D.C.). In a cell,
the internal resistance
is the sum of the ionic and electronic resistances
of the cell
A device that conditions and
converts DC to AC. There are modified sine wave (MSW) inverters, which are
in reality closer to square wave than a sine wave. MSW inverters have from
30 to 40% Total Harmonic Distortion (THD), or distortion from a pure sine
wave. The utility grid averages, about, 3% THD. A Trace SW inverter has
from 3 to 5%, and an Exeltech inverter has 1 to 2% THD.
An atom or a group of atoms that has acquired a
net electric charge by gaining or losing one or more electrons. A
"positive ion" is an atom with fewer electrons, and a
"negative ion" is an atom with more electrons.
A voltage drop associated with the electrical resistance
(R) of a battery or current flow (I). The
voltage drop is the product of the current (in amperes)
and the resistance
Housing, or container, for one or more cells.
Forming of plates
in the cell
jar, vs. tank formation.
A short length of conductor used to connect or cut out
part of an electrical circuit.
One thousand volts.
One thousand watts.
Kilowatt Hours (kWh)
Unit of energy (1000 watts) to perform work.
If a 100 watt light is on for 10 hours it has consumed 1 kWh of energy.
Chemical element used in lead-acid
Still the most popular battery used today
its main application is for the automobile industry, although it has a
growing number of other applications. Its advantages are low cost, high
voltage per cell
and good capacity
life. Disadvantages are poor low temperature characteristics, it is
relatively heavy, and it cannot be left in a discharged state for too long
without being damaged. Related Batteries: Absorbent Glass Matt (AGM)
Welding of lead
or alloy parts.
A white lead compound formed by reaction of very dilute electrolyte
or water and metallic lead
or lead alloys.
A general term for any of the lead oxides used to
A brown lead oxide, which is the positive material in a
fully formed positive plate.
Lead Plated Part
Hardware that has a thin protective layer of lead
electrode deposited on the surface.
The chief component of the active
material of a fully charged negative plate.
A compound that results from the chemical action of sulfuric
acid on oxides of lead
or on lead metal.
Horizontal lines molded or painted near tops of battery containers indicating maximum and
The maximum current drain under which the particular battery will perform adequately under a
continuous drain. The rate is based on whatever drain rate reduces the
running voltage to 1.1 volts.
Load Current (Load)
current provided by a battery, or drawn by
a battery-powered device. Can also refer to any device consuming energy. Usually expressed
in terms of watts or amps.
A battery’s loss of otherwise usable chemical energy by
currents that flow within the cell
of a battery regardless of its connection
to an external circuit. Also known as Self Discharge.
Loss of Charge
loss in a cell
or battery standing on open circuit as a
result of local action.
A portion of the grid used for support of the plate
group, usually a hanging lug on the top edge of the grid. Also, a tab on
the grid used for connection of plate
to strap and other plates.
A fully or semiautomatic grid or small parts casting
MF (Maintenance Free Battery)
A VRLA sealed absorbed glass mat (AGM)
Capacity test in which the operator disconnects the battery from the test load after all cells
have reached the prescribed final voltage. With fixed resistance
loads, boost cells are used to keep the discharge rate fairly constant as
the test cell
voltages drop rapidly near the final voltage. Electronic load manual discharges
generally do not require boost cells.
A phenomenon in which a cell
or battery operated in successive cycles
to the same, but less than full, depth of discharge
temporarily loses the rest of its capacity
at normal voltage levels.
A veneer or grooved-type separator
made of any material that has many microscopically small pores.
The voltage of a battery midway in the discharge
between the start of the discharge
and the end voltage.
One thousandth of an ampere.
Refers to battery capacity.
A 1/1000th of an amp, e.g.: 1.0Ah
One thousandth of a volt.
Modified Constant Voltage Charge
A charge in which charging current voltage is held
substantially constant while a fixed resistance
is inserted in the battery circuit,
producing a rising voltage characteristic at the battery
terminals as the charge progresses.
A cast iron or steel form used to produce a casting of
definite shape or outline.
A spray applied to metal molds that acts as a release
agent and an insulator against rapid heat transfer.
crystals that can grow at high current density areas of negative plates—
along edges, at feet or at plate
lugs— and cause short-circuiting.
A terminal or electrode, which has an excess of electrons.
The grid and active
material that current flows to from the external circuit when a battery is discharging.
The terminal from which current flows through the
external circuit to the positive terminal when the cell
One of the most proven and historically most widely used rechargeable
batteries. Very dependable and "robust" but contain cadmium and
have relatively low capacity
when compared to other rechargeable systems. Very good high rate discharge
capabilities make them very popular in high drain applications such as
The characteristic operating voltage or rated voltage of a battery
A measure of resistance
that causes one volt to produce a current of one ampere.
Expresses the fundamental
relationship between voltage, current, and resistance.
Current (Amps, or I) in a circuit equals Voltage (E) divided by Resistance
(Ohms, or R):
I = E / R or Amps = Volts / Ohms
By using simple algebra, Ohm's
law can be rearranged as:
E = I x R or Volts = Amps x Resistance
It can also be rearranged as: R
= E / I or Resistance
= Volts / Amps
The current flow in a circuit
depends on both the voltage of the source (battery, or PV) and the resistance
of the circuit.
Oil of Vitriol
Concentrated commercial sulfuric
acid, abbreviated OV or O.V.
The state of a battery
when not connected to either a charging source or a load circuit.
The difference in potential between the terminals of a cell
or multiple cells in a battery when the circuit is open (no load
The forcing of current through a cell
after all the active
material has been converted to the charged state, that is, continued
charging after reaching 100 percent state-of-charge.
The process of discharging a cell
or battery beyond its cutoff voltage and
possibly into voltage reversal.
A battery operates through electrochemical
reactions called oxidation
and reduction. These reactions involve the exchange of electrons between
chemical species. If a chemical species loses one or more electrons, this
is called oxidation.
The opposite process, the gain of electrons, is called reduction.
Oxide (of lead)
A compound of lead
and oxygen in one of several proportions used to prepare battery paste.
A casting consisting of two or more grids made
simultaneously in a single mold.
Term used to describe the interconnection of cells
or batteries in which all the like terminals are connected together
(positive to positive, negative to negative. Results in increased capacity,
but the voltage remains the same.
The phenomenon by which a metal, although in conditions of thermodynamic
instability, remains indefinitely unattacked because of modified or altered
Chemical symbol for lead.
Chemical symbol for litharge.
Chemical symbol for lead peroxide.
The portion of pasted
material contained in a grid section framed by adjacent horizontal and
vertical members exclusive of forming bars.
See Lead Peroxide.
A cast bar of lead
or lead alloy.
A grade of highly refined, unalloyed lead.
Distance between centerlines of adjoining plates
of opposite polarity in a cell.
One half the size of a strap center upon which the plates
of like polarity are burned.
In electricity, the condition of being positive or negative.
The lowering of the potential of a cell
or electrode from its equilibrium value caused by the passage of an
The ratio of open spaces or voids in a material to the
volume of its mass.
A terminal or electrode, which has a shortage of electrons.
The grid and active
materials of a storage battery from
which current flows to the external circuit when the battery is discharging.
A thermally reactive device, which becomes highly resistive at a specific
Coefficient (PTC) temperature or current.
The terminal that current flows toward in the external
circuit from the negative terminal.
Terminal or other conductor that connects the plate
group strap to the outside of the cell.
The amount of work being done.
The unit measurement of power is called a Watt (W). Electric power is
simply the product of voltage times current.
Watts = Volts x Amps or Volts = Watts / Amps and also as Amps
= Watts / Volts
A battery which is not intended to be
recharged and is discarded when the battery
has delivered all of its electrical energy.
The positive and negative plates
are stacked rather than rolled as done in a cylindrical cell.
A periodic current drain of higher than normal drain rates.
A charge time that is between slow charge and fast charge.
Rate of Charge
See Starting Rate and Finishing Rate.
The number of ampere-hours
a battery can deliver under specific
conditions (e.g., rate of discharge, end voltage, temperature); usually
specified by the battery manufacturer.
An unformed plate.
A battery, which, after discharge,
may be restored to the fully charged state by the passage of an electrical
current through the cell
in the opposite direction to that of discharge.
A device that converts alternating (ac) current into unidirectional
(dc) current because of a characteristic that permits appreciable flow of
current in only one direction.
A red oxide of lead
used in making active
Electrode used to measure acid
concentration or plate
state of charge.
The degree to which the flow of electrons is opposed by the material the
electrons must pass through, or opposition to the flow of current. Unit of
measurement is called an Ohm, stated as R, or by the Greek letter omega.
All conductors have some resistance;
this is necessary because if a conductor had no resistance
the connection would be a short circuit with excessive current flow.
Insulators have high resistance
and conductors have low resistance.
Bad connections (loose, corroded, or dirty) have high resistance
and can result in little current flow and heat.
A device used to introduce resistance
into an electrical circuit.
A sheet of glass mat, perforated or slotted rubber,
plastic or some other material installed on each face of the positive plates
in certain types of cells,
to deter loss of active
The changing of the normal polarity of a battery
due to Over discharge.
A vertical or nearly vertical ridge of a grooved separator
A venting mechanism designed into a cell,
which activates under specific conditions of abuse to relieve internal
These types of batteries confine the
electrolyte, but have a vent or valve to allow gases to escape if internal
pressure exceeds a certain threshold. During charge, a lead-acid battery
generates oxygen gas at the positive electrode. Sealed lead-acid batteries
are designed so that the oxygen generated during charging is captured and
recombined in the battery. This is called an oxygen recombination cycle
and works well as long as the charge rate is not too high. Too high of a
rate of charge may result in case rupture, thermal runaway, or internal
mechanical damage. The valve-regulated battery is the most common type of
sealed battery. It was developed for stationary and telecommunication
battery applications. These types of sealed batteries have a
spring-controlled valve that vents gases at a predetermined pressure.
Typical pressure thresholds are from 2 to 5 psig, depending on the battery
design. Although the term valve regulated is often used synonymously to
describe sealed lead-acid batteries, not all sealed batteries are
valve-regulated. Some battery designs employ replaceable vent plugs or
other mechanisms to relieve excess pressure. Sealed batteries were developed
to reduce the maintenance required for batteries in active service. Since
are preserved by trapping and recombining off-gasses, there should not be
any need to add distilled water over the life of the battery. These
batteries are often misnamed maintenance free. In fact, all maintenance
practices applicable to unsealed type batteries are applicable to sealed
type batteries. The only exception is that electrolyte levels
cannot, and should not need to be, maintained. Sealed type batteries are
often avoided for backup power source applications for several reasons. One
reason is that the state of charge of sealed type batteries cannot be
ascertained by the usual specific gravity measurement. Reliable alternative
methods to measure the state of charge for sealed type batteries are under
development. A second reason is their sensitivity to high temperatures.
A battery that can be recharged and reused
Reclaimed as opposed to virgin lead.
Secure Waste Landfill
A landfill designed for disposal of normal household trash but which meets
government standards designed to protect the environment.
The sludge or active
that drop to the bottom of cells.
The portion of a container beneath the element; sediment
from the wearing of the plates
collects here without short-circuiting.
The tendency of all electrochemical cells
to lose energy (capacity)
due to internal chemical reactions within the cells.
Also called local action.
An ionic permeable electronically non-conductive spacer or material, which
prevents electronic contact between electrodes of opposite polarity in the
The interconnection of cells
in such a manner that the positive terminal of the first is connected to
the negative terminal of the second, and so on, resulting in increased
voltage. Note that the current stays the same when series
in a battery other than pilot cells. They
are so called because the cells
are usually connected in series.
Series Parallel Connection
arranged in a battery so two or more
strings of series
each containing the same number of cells,
are connected in parallel;
this increases battery capacity.
The period of useful life of a battery
before a predetermined end-point voltage is reached.
The duration of storage under specified conditions at the end of which the battery still retains the ability to give a
An unwanted electrical connection between a negative and positive source.
Short circuits can damage the battery and
equipment and can cause sparks or fire.
The initial value of the current obtained from a battery
in a circuit of negligible resistance.
A low value resistor used in parallel
with a meter to increase the amount of current the meter can measure.
A primary battery (non-rechargeable) it is
a major contribution to miniature power sources, and is well suited for
hearing aids, instruments, photoelectric exposure devices and electronic
watches. These cells
are primarily made in the smaller button sizes.
Extremely fine parallel glass fibers used in retainers
next to positive plates
to retard shedding.
A battery for
automotive use in starting, lighting and ignition.
Typically an over-night charge lasting about 14 hours at a charge current of
0.1C. Battery does not require instant
removal when fully charged.
Battery with internal circuit enabling
some communication between the battery and
the user. Some batteries feature a capacity
indicator only; others offer an external bus to interface with the
equipment the battery power and the
The primary process for recovering lead
and antimony from scrapped batteries and scrap from battery manufacture.
A manufacturing process following pasting that soaks
certain types of lead plates
acid. This provides a protective surface and also sulfate helpful in
container and tank formation.
Sodium Carbonate (Na2CO3) used in neutralizing sulfuric
acid in spills or effluents.
whose voltage rises above its defined boundaries during charging. This
voltage rise may be caused by high cell
impedance as a result of prolonged battery
storage, very cold battery temperature or
lack of electrolyte.
material, usually from positives, during formation due to incomplete or
improper plate curing.
The ratio of the energy output of a cell
or battery to its weight (Wh/kg). This
term is used interchangeably with gravimetric energy density.
Specific Gravity (SG or SPGR)
The weight of the sulfuric
compared to water, or the ratio of a liquid's density to the density of
water. Because sulfuric acid is denser than water, the difference can be
measured with a battery hydrometer
(tool that measures SPGR) and the approximate state of charge can be
Sponge Lead (Pb)
A porous mass of lead crystals and the chief material of a full-charged
assembly operation, alternately piling plates
in a burning box prior to attachment of straps and posts.
Any of Conventional, YuMicron or YuMicron CX batteries
consisting of flooded electrolyte
The use of batteries in which they are charged by an application to be
ready for use if the primary power to the application fails. Also called
float or backup.
Loss of charge by an idle cell
or battery, resulting from local action.
A beginning charging rate that does not produce gassing
or temperatures in excess of 110°F.
Starved electrolyte either on
Glass fibers (AGM,
Absorptive Glass Mat) or as a Gel
(Gel technology). Starved electrolyte allows internal gas circulation.
State of Charge
remaining in a battery. A ratio, expressed
in percent, of the energy remaining in a battery in relation to its
capacity when full.
Pre-cast or cast-on piece of lead
or lead alloy used to connect plates
into groups and to connect groups to the post.
Spacing between centers of adjacent plates
in a group.
Layering of high specific gravity electrolyte
in lower portions of a cell,
where it does not circulate normally and is of no use.
materials contain an appreciable amount of lead sulfate.
Growth of lead sulfate crystals in Lead-Acid
batteries, which inhibits current flow. Sulfation is caused by storage at
low state of charge. During recharge, a current flow of electrons is forced
through the battery in the opposite direction of discharge
by the application of voltage across the battery's terminals. The chemical
bond between the lead
and the sulfate ions is broken, and the sulfate ion is released back into
the electrolyte solution. When all the sulfate ions have been removed from
and are in the electrolyte, the battery is considered fully charged.
If the battery is not recharged, and lead sulfate ions stay on the plates
long enough (about three to four weeks), the sulfate becomes hardened
crystals and is difficult to remove. This is called sulfation. Storage
capacity of the battery is reduced when the plates
are sulfated. Sulfation can even render an otherwise good battery useless.
The principal acid compound of sulfur, sulfuric acid in
dilute and highly pure form is the electrolyte
A shallow burn used to tack together two lead
Electrolytic processing of plates
prior to assembly in large tanks of sulfuric
In storage cells,
specific gravity and charging voltage vary inversely with temperature,
while the open circuit voltage varies directly though slightly with
A protective or safety device (e.g., thermostat, PTC, etc.) which senses
temperature in a battery and opens or cuts
off the electrical circuit if the specified temperature is exceeded, thus
preventing a further rise in temperature due to the charge or discharge
of a battery.
A device at the end of a cell
or wire for making a connection to an adjoining cell
A length of insulated cable, one end connected to the battery terminal post, and the other fitted with
a plug, receptacle, lug or other device for connection to an external
A temperature sensitive switch.
A method of casting in which molten metal is poured, usually by hand,
into a top gated mold.
A low rate charge following the main charge, designed to ensure maximum capacity.
Steel Housing for one or more 2-volt cells.
Growth of a lead dendrite or filament through a crack or
hole of a separator,
short-circuiting the cell.
A charge at a low rate, balancing losses through local action and/or
to maintain a cell
or battery in a fully charged condition.
A time / voltage relay used in charging equipment.
Typically allows battery to charge to 80%, then times out after 3 hours to
that has not been electrolytically formed.
acid above the lower edges of the plates
that takes part in the discharge
reactions that occur within a cell.
An opening that permits the escape of gas from a cell
The seal for the vent and filling well of a cell
cover, containing a small hole for escape of gas.
The hole or holes in a cell
cover that allow fluids to be checked, electrolyte
to be added, and gas to escape. The vent plug fits into the vent well.
The members in a plate
The unit of measurement of electromotive force, being
the force needed to send a current or one ampere
through a conductor with a resistance
of one ohm. Or, the electromotive force, which will cause current to flow.
A standard definition of the volt is: an emf of 1 Volt is necessary to move
a current of 1 Amp through a 1-Ohm resistor. A voltmeter measures the
difference in potential between two points. It may be helpful to think of
voltage to electricity flow as pressure is to water flow.
The ratio of the average voltage of a cell
or battery during discharge
to the average voltage during subsequent recharge.
A unit of measuring electrical pressure. Batteries are rated in DC (Direct
Time delay for a battery to deliver the required operating voltage after it
is placed under load.
An abnormal drop in voltage below expected values during the discharge
of a battery.
A system that incorporates a mechanical identifier on batteries and devices
to ensure only batteries of the correct voltage are connected to the
The difference between maximum and minimum cell
voltages within a battery or string of cells
when all cells
are charging and discharging.
A device that regulates the output of a generator or alternator by
controlling the current and voltage.
The changing of the normal polarity of a battery
due to over discharge.
An instrument for measuring voltage.
Volumetric Energy Density
The ratio of the energy output of a cell
or battery to its volume (Wh/L).
VRLA (Valve Regulated Lead-Acid)
Sealed batteries, which feature a safety valve venting
system, designed to release excessive internal pressure, while maintaining
sufficient pressure for recombination of oxygen and hydrogen into water.
A battery design where the structural
support for the cells
is formed by an open plastic framework.
Adding water to battery
to replace loss from electrolysis and evaporation, to bring it to the Proper
The level of the acid/water
in a battery cell.
Maintaining the correct
water level is essential to achieving maximum battery life, productivity
and return on investment.
A unit of power or measurement of energy, arrived at by multiplying the
voltage by the amperage. Power is the rate of
using energy to do work. Amperage x voltage = watts. Watts are a
constant; if the voltage is higher then the amperage will be lower to
produce the same amount of wattage or vise versa.
A common measurement of energy produced in a given amount of time arrived
at by multiplying the voltage by the amp hours.
The number of watt-hours a storage battery can deliver under specific conditions of
temperature, rate of discharge and final voltage.
Watt-hour Efficiency A
storage battery’s energy efficiency expressed as ratio of watt-hour output
to the watt-hours of the recharge.
An electric motor that measures and registers electrical
energy in watt-hours.
Wet Shelf Life
The time a wet secondary cell
can be stored before its capacity
falls to the point that the cell
cannot be easily recharged.
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