Glossary - ups-singapore.com

Acid
Sulfuric acid, used to describe the electrolyte or liquid in a cell.

Active Materials
This refers to the positive and negative plate pastes that provide energy from a battery when it is discharged. For a lead-acid battery, the positive active material, or PAM, is lead dixide; the negative active material, or NAM, is sponge lead.

Activation
Making a dry cell functional by adding electrolyte.

AGM Batteries
AGM battery is a lead-acid electric storage battery that is sealed using special pressure valves and should never be opened, is completely maintenance-free. Has all of its electrolyte absorbed in separators consisting of a sponge-like mass of matted glass fibers. Uses a recombination reaction to prevent the escape of hydrogen and oxygen gases normally lost in a flooded lead-acid battery (particularly in deep cycle applications). Is non-spillable, and therefore can be operated in virtually any position. However, upside-down installation is not recommended.

What is an AGM SLA Battery

AGM is the abbreviation for Absorbed Glass Mat

AGM Batteries are:
*	also referred to as SLA batteries (Sealed Lead Acid)
*	Valve Regulated-Rechargeable & Maintenance Free
*	sometimes called “starved electrolyte” or “dry”, because the fiberglass mat is only 95% –saturated with Sulfuric acid and there is no excess liquid
*	Non-Spillable – – > will not leak acid even if dropped or broken
*	classified as non-hazardous Complies with DOT HMR49, Non-Hazardous Materials
*	able to be mounted in any position
AGM Batteries:
*	will not freeze
*	release very little hydrogen gas and only under a heavy discharge
*	have low internal resistance so less heating occurs during charging and discharging
*	possess wide charge and discharge current ranges
*	have very low self-discharge rates, normally < 3%

AGM Deep Cycle Batteries are capable of withstanding a large number of deep discharge cycles without loosing capacity

AGM Batteries are cost effective

Air Oxidized
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 electrical energy.

Alloy
A combination of two or more metals. See Antimonial Lead Alloy and Calcium Lead Alloy.

Ambient Temperature
The surrounding temperature, usually refers to room temperature.

Alternating Current
A pulsating electric current in which direction of flow is rapidly changed, so the terminal becomes in rapid succession positive, then negative. Abbreviated AC.

Ammeter
An instrument for measuring electrical current.

Ampacity
Current carrying capacity in amperes.

Ampere
The unit of electrical current equal to the steady state current produced by one volt applied across a resistance of one ohm.

Ampere-Hour
The value obtained when the battery is normally used to define capacity of the battery. It is current in amperes, multiplied by the time in hours, during which current flows from the battery.

Ampere-Hour Capacity
The number of ampere-hours that can be delivered by a storage battery under specified conditions as to temperature, rate of discharge and final voltage.

Ampere-Hour Efficiency
The electrochemical efficiency of a storage battery expressed as the ratio of ampere-hours output to the ampere-hours input required for recharge.

Ampere-Hour Meter
An instrument that registers the quantity of electricity in ampere-hours.

Anode
An electrode through which current enters any non-metallic conductor. Specifically, an electrolytic anode is an electrode at which negative ions are discharged, positive ions are formed, or at which other oxidizing reactions occur.

Antimonial Lead Alloy
The most 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.

Antimony
A hard, brittle, silver-white metal with a high luster from the arsenic family.

Assembly
1. Combining various parts into a finished battery. 2. Any particular arrangement of cells, connectors and terminals to form a battery.

Automotive Battery
SLI Battery of 3 or 6 cell used for starting, lighting and ignition of cars, trucks, buses, etc.

Available Capacity
The capacity available from the battery based on its state of charge, rate of discharge, ambient temperature and specified cut-off voltage.

Average Voltage
A storage battery’s average value of voltage during a period of charge or discharge.

Battery
Two or more cells, connected together, normally in series. At times, a single cell may be referred to as a battery.

Battery (Storage)
A connected group of two or more storage cells. Common usage applies this term to a single cell used independently.

Bridge
The ribbed supporting structure in the bottom of a battery container that provides sediment space under the elements, thereby preventing short circuits.

Burning
Welding together two or more lead or lead alloy parts such as plates. straps, connectors.

Burning Center
The center-to-center distance between adjacent plates of the same polarity.

Burning Stick
A lead or lead alloy stick used as a supply of joining material in lead burning.

Cadmium
A metallic element highly resistant to corrosion, used as a protective plating on certain parts and fittings.

Cadmium Electrode
A third electrode for separate measurements of the electrode potential of positive and negative plate groups.

Calcium Lead Alloy
A lead base alloy that is sometimes used for battery parts in place of antimonial lead alloys.

Capacity
The electrical energy available from a cell or battery expressed in ampere-hours, It refers to the discharge of a constant current for a measure time to a specified cut-off voltage (normally 1.75V/2V cell), at a specified temperature.

Capacity Recovery
Also called recoverable capacity. This is the discharge capacity that can be restored to a cell or battery through various treatments when it had dropped to very low capacity levels.

Capacity Test
A test that discharges the battery at constant current at room temperature to a cutoff voltage of usually 1.7 volts/cell.

Cast
Forming a molten substance into a shape by introducing the material into a mold and allowing it to solidify.

Casting
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 solidify.

Cast-On Strap
A multiple connector that had been cast onto the plates directly in a combination mol/burning contrasts with burning of plates and prefabricated straps.

Cathode
An electrode through which current leaves any non-metallic conductor. Specifically, an electrolytic cathode is an electrode at which positive ions are discharged, or negative ions are formed, or at which other reducing actions occur.

Cell
The minimum unit of the battery that composes a storage battery: the nominal voltage of a cell of the Lead-Acid Battery is 2.0V. Most batteries are made of 2 or more cells. Typically 3 cells for a 6Volt, and 6 cells for a 12Volt battery.

Cell (Primary)
A cell designed to produce electric current through an electrochemical reaction that is not efficiently reversible and hence the cell, when discharged, cannot be efficiently recharged by an electric current.

Cell (Storage)
An electrolytic cell for generation of electric energy, in which the cell after discharge may be restored to a charged condition by an electric current flowing in a direction opposite to the flow of current when the cell discharges.

Charge
The process of restoring electrical energy to a cell or battery, in the process increasing the cell voltage.

Charge Efficiency
Ratio of the ampere-hours delivered during discharge divided by the ampere-hours put into the battery during recharge.

Charged
A storage cell at maximum ability to deliver current. The positive plates contain a maximum of lead oxide and a maximum of lead sulfate, and the negative plates 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 containing electrolyte and ready to deliver current.

Charging
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).

Charging Rate
The current, expressed in amperes, at which a battery is charged.

Circuit
A system of electrical components through which an electric current is intended to flow. The continuous path of an electric current

Cold Crank Test
A test that applies a high rate of discharge (up to 300 amperes) to a battery at 0°F, and the 30 second cell voltage must be above 7.2v.

Constant Current Charge
One of the charge methods which has current limitation. According to the charge time, some fixed amount of capacity is charged. Therefore this charge method requires some devices which prevent overcharge such as timer etc., for VRLA battery.

Constant Potential Charge or Constant Voltage Charge
A charge that holds the voltage at the terminals at a constant value.

Constant Voltage Charge
One of the charge methods which has voltage limitation. When the discharged battery is charged by this way, the charge current is reduced automatically according to the state of charge. This is the most recommendable charge method for VRLA batteries.

Container
Housing for one or more cells, commonly called a “jar”.

Cover
The lid of an enclosed cell, generally made of the same material as the container and through which the posts and vent plug extend.

Cover Inserts
Lead or lead alloy rings molded or sealed into the cell cover, and that the element posts are burned to, thereby creating an effective acid creep-resistant seal.

Creepage
Travel of electrolyte up the surface of electrodes of other parts of the cell above the level of the main body of the electrolyte.

Curing
Chemical conversion process that changes lead oxides and sulfuric 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 during formation.

Current
The time rate of flow of electricity, normally expressed as amperes, like the flow of a stream of water.

Cut-Off Voltage
The final voltage of a cell or battery at the end of charge or discharge.

Cutting (of acid)
Dilution of solution of sulfuric acid to a lower concentration.

Cycle
A single charge and discharge of a cell or battery.

Cycle Life
The number of cycles a cell or battery repeatedly by charging and discharging.

Cycle Service
Battery operation that continuously subjects a battery to successive cycles of charge and discharge, e.g., motive power service.

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

Deep Discharge
The discharge of a cell or battery to 80-100% of its rated capacity.

Depth of Discharge
Frequently expressed as a percentage. It is the amount of capacity removed from ac ell or battery during discharge.

Dielectric Test
An electric Test performed on jars, containers and other insulating materials to determine their dielectric breakdown strength.

Diffusion
The intermingling or distribution of particles or molecules of a liquid.

Direct Current
A one-direction current. Abbreviated DC.

Discharge
The function of removing current from a cell or battery.

Discharged
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 terminals.

Discharge Voltage
The closed circuit voltage of a battery during discharge.

Discharge Rate
Normally expressed as a fraction of C: it is the rate at which current is taken from a cell or battery.

Dry Charged
A negative plate that has been subjected to the dry charging process.

Dry Charging
Manufacturing process in which tank-formed negatives (or elements) are washed free of acid and then dried.

Efficiency
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.

Electrode
The positive or negative plate holding the active materials in the cell.

Electrode (Electrolyte) Potential
The difference in potential between the electrode and the immediately adjacent electrolyte, expressed in terms of some standard electrode potential difference.

Electrolysis
Electrochemical reaction that causes the decomposition of a compound.

Electrolyte
Conducts ions in the cell. Lead-Acid Batteries use sulfuric acid solution.

Electromotive Force (EMF)
Electrical pressure or potential, expressed in volts.

Element
An assembly of a positive plate group, negative plate group and separators.

End Gravity
The specific gravity of a cell at the end of a prescribed discharge (usually 6 to 8 hours).

Energy Density
Ratio of battery energy content in watt hours to battery weight in volume.

Envelope
See perforated container.

Equalizing Charge
An extended charge given to a storage battery to ensure complete restoration of active materials in all the plates of the cells.

Expander
an ingredient in the negative paste that delays shrinking and solidifying of the sponge lead of the finished plate, thereby enhancing negative plate capacity.

Ferroresonant charger
A constant volt power supply containing a special transformer-capacity combination that changes operating characteristics as the draw is varied, ensuring that voltage output remains constant.

Filling Gravity
The specific gravity of acid used to fill batteries.

Final Voltage
The cut-off voltage of a battery. The prescribed voltage reached when the discharge is considered complete.

Finishing Rate
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
Discharge of a cell or battery through a fixed resistive load, the current being allowed to fall off as the terminal voltage decreases.

Float Charging
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.

Float Plate
A pasted plate.

Float Service
A battery operation in which the battery is normally connected to an external current source; for instance, a battery charger which supplies the battery load under normal conditions, while also providing enough energy input to the battery to make up for its internal quiescent losses, thus keeping the battery always up to full power and ready for service.

Foot
Projections from the grid at the bottom edge, used to support the plate group.

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.

Formed
Plates that have undergone formation.

Freshening Charge
A charge given batteries in storage to replace the standing loss and ensure that every plate is periodically bought up to full charge.

Full Charge Gravity
Specific gravity of the electrolyte when cells are fully charged and properly leveled.

Gang Vent
Vents for usually six adjacent cells that are connected to a common manifold.

Gassing
Bubbles from gases being released at one or more of the electrodes during electrolysis.

Gelled Electrolyte
Refers to a type of VRLA cell or battery where the electrolyte is immobilized in a gel made from fumed silica, said gel then contained within a coarse glass mat or micro porous separator matrix. This gel mat serves as the separator in the VRLA cell in place of the more common glass micro fiber material.

Glass Mat
Fabric made from glass fibers with a polymeric binder such as styrene or acrylic which is used to help retain positive active material.

Gravity
Specific gravity.

Gravity Drop
The number of points reduction or drop of specific gravity of the electrolyte from cell discharge.

Grid
A metallic framework used in a battery for conducting electric current and supporting the active material.

Group
One or more plates of one type-positive or negative-burned to a post or strap.

H2SO4
Sulfuric Acid.

High Rate
On charge, any rate higher than the normal finishing rate.

High-Rate Charge/Discharge
Charge/discharge processes that are carried out at relatively high current densities, with the multiple of C rate depending upon the battery design.

Hydration (Lead)
Reaction between water and lead or lead compounds. Gravities lower than those found in discharged cells are apt to produce hydration, which appears as a white coating on plate groups and separators in a cell.

Hydrometer
A device used to measure density or specific gravity of electrolyte solutions.

Hydroset
Curing process for plates that oxidizes the lead paste, reducing free lead to a few percent of total.

Initial Voltage
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.

Insert
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.

Intercell Connector
Conductor of lead or lead alloy used to connect two battery cells.

Internal Impedance/Resistance
A measure of a cell’s electrical resistance to current flow, resulting in small or large voltage drops and some level of resistive heating. Impedance (AC) and resistance (DC) values are proportional but different, resulting from differences in measurement methodology.

Internal Resistance
Resistance within a cell or battery to the flow of electric current, measured by the ratio of the change in voltage to a specified change in current for a short period of time.

Internal Short Circuit
Positive plates and negative plates touch together through at the inside of the cell.

Jar
Housing, or container, for one or more cells.

Jar Formation
Forming of plates in the cell jar.

Jumper
A short length of conductor used to connect or cut out part of an electrical circuit.

Kilovolt
One thousand volts.

Kilowatt
One thousand watts.

Kilowatt Hours
A measure of energy or work accomplished, being 1000 watt hours.

Lead
(pb) Chemical element used in lead acid batteries.

Lead Burning
Welding of lead or alloy parts.

Lead Hydrate
A white lead compound formed by reaction of very dilute electrolyte or water and metallic lead or lead alloys.

Lead Oxide
A general term for any of the lead oxides used to produce batteries.

Lead Peroxide
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.

Lead Sponge
The chief component of the active material of a fully-charged negative plate.

Lead Sulfate
A compound that results from the chemical action of sulfuric acid on oxides of lead or on lead metal.

Level Lines
horizontal lines molded or painted near tops of battery containers indicating maximum and minimum electrolyte levels.

Life
The time period until the battery can no longer be used because it has lost its characteristics.

Litharge
A yellow-red oxide of lead sometimes used in making active material.

Load
A device or mechanism external to a battery, and which is powered by the battery, The resistance of the load and the battery voltage dictate the current flow rate, and thus the run time for the battery.

Local Action
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.

Loss of Charge
Capacity loss in a cell or battery standing on open circuit as a result of local action.

Lug
A portion of the grid used for support of the plate group, usually a hanging lug on the top edge of the grid. Also, at tab on the grid used for connection of plate to strap and other plates.

Machine Casting
A fully or semiautomatic grid or small parts casting operation.

Maintenance Free
Secondary cells that are not sealed require periodic addition of water, Sealed Lead-Acid Batteries do no require such maintenance. Therefore they are called “maintenance free;.

Manual Discharge
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.

Microporous Separator
A veneer or grooved-type separator made of any material that has many microscopically small pores.

Millivolt
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.

Mold
A cast iron or steel form used to produce a casting of definite shape or outline.

Mold Coat
A spray applied to metal molds that acts as a release agent and an insulator against rapid heat transfer.

Moss
Lead crystals that can grow at high current density areas of negative plates–along edges, at feet or at plate lugs–and cause short circuiting.

Motive Power Battery
A cycle service battery designed to provide energy necessary to for electrically powered industrial trucks.

Negative Plate
The grid and active material that current flows to from the external circuit when a battery is discharging.

Negative Terminal
The terminal that current flows toward in the external circuit from the positive terminal.

Nominal Voltage
A nominal value to be used to indicate the battery voltage; for the sealed Lead-Acid Battery; the nominal voltage is 2V/celll.

OHM
A unit of electrical resistance.

Oil of Vitriol
Concentrated commercial sulfuric acid, abbreviated OV or O.V.

Open Circuit
The state of a battery when not connected to either a charging source or a load circuit.

Open Circuit Voltage
The measured voltage of the cell or battery without a load attached.

Overcharge
The continuous charging of a cell after it achieves 100% of capacity. The battery life is reduced by prolonged over charge.

Overcharge Current
The charge current supplied during overcharge. Batteries can accept continuous overcharge at recommended rate and temperatures.

Oxide (of lead)
A compound of lead and oxygen in one of several proportions used to prepare battery paste.

Panel
A casting consisting oftwo or more grids made simultaneously in a single mold.

Pb
Chemical symbol for lead.

PbO
Chemical symbol for litharge.

PbO2
Chemical symbol for lead peroxide.

Pellet
The portion of pasted material contained in a grid section framed by adjacent horizontal and vertical members exclusive of forming bars.

Peroxide
See Lead Peroxide.

Pig
A cast bar of lead or lead alloy.

Pig Lead
A grade of highly refined, unalloyed lead.

Plate
A pasted grid.

Plate Centers
Distance between center lines 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.

Polarization
Change in voltage at terminals when a specified current is flowing; equal to the difference between the actual and the equilibrium (constant open circuit condition) potentials of the plates, exclusive of the internal resistance drop.

Porosity
The ratio of open spaces or voids in a material to the volume of its mass.

Positive Plates
The grid and active materials of a storage battery from which current flows to the external circuit when the battery is discharging.

Positive Terminal
The terminal from which current flows through the external circuit to the negative terminal when the cell discharges.

Post
Terminal or other conductor that connects the plate group strap to the outside of the cell.

Pure Lead
Pig Lead.

Quick Recharge ability
The ability of quick charge acceptance of the batteries. Quick recharge requires not only good charge acceptability but also safety devices such as thermostat, timers, etc.

Rated Capacity
The manufacture’s rated capacity of the cell (see: capacity).

Rate of Charge
See Stating Rate and Finishing Rate.

Raw Plate
An unformed plate.

Rectifier
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.

Red Lead
A red oxide of lead used in making active material.

Reference Electrode
Electrode used to measure acid concentration or plate state of charge.

Refresh Charge
A recovery charge which is done periodically for recovering the lost capacity of batteries due to self discharge.

Resistance
The opposition of a conductor to the passage of an electrical current, usually expressed in ohms.

Resistor
A device used to introduce resistance into an electrical circuit.

Retainer
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 material.

Reversal
A change in the normal polarity of a cell or battery.

Rib
A vertical or nearly vertical ridge of a grooved separator or spacer.

Secondary Battery
A battery that can be charged and discharged repeatedly. Example: Lead-Acid batteries, Nickel Cadmium batteries.

Secondary Lead
Reclaimed as opposed to virgin lead.

Sediment
The sludge or active material shed from plates that drops to the bottom of cells.

Sediment Space
The portion or a container beneath the element; sediment from the wearing of the plates collects here without short-circuiting.

Self-discharge
The loss of capacity by a battery while in the stored or unused condition. The rate of self-discharge is affected by ambient temperature.

Separator
The material separating the electrodes. Used to hold the electrolyte. Normally glass fiber is used.

Series Cells
All cells in a battery other tan pilot cells. They are so called because the cells are usually connected in series.

Series Parallel Connection
Cells arranged in a battery so two or more strings of series connected cells, each containing the same number of cells, are connected in parallel; this increases battery capacity.

Shelf Life
The life of a battery when stored in the unused condition.

Short Circuit Current
The current that flows when the two terminals of a cell or battery are inadvertently connected to each other.

Side Terminal
SLI battery design with two through-the container current connections on one side instead of two posts on top.

SLI Battery
A battery for automotive use in starting, lighting and ignition.

Sliver, Slyver
Extremely fine parallel glass fibers used in retainers next to positive plates to retard shedding.

Smelting
The primary process for recovering lead and antimony from scrapped batteries and scrap from battery manufacture.

Soaking
A manufacturing process following pasting that soaks certain types of lead plates in sulfuric acid. This provides a protective surface and also sulfate helpful in container and tank formation.

Soda Ash
Sodium carbonate (Na2CO3) used in neutralizing sulfuric acid in spills or effluents.

Spalling
Shedding of active material, usually from positives, during formation due to incomplete or improper plate curing.

Sponge Lead
(Pb0 A porous mass of lead crystals and the chief material of a full-charged negative plate.

Stacking
A cell assembly operation, alternately piling plates and separators in a burning box prior to attachment of straps and posts.

Stand-by Use
A method of using secondary batteries in which the battery is constantly charged so that it is always ready for use.

Standing Loss
Loss of charge by an idle cell or battery, resulting from local action.

Starting Rate
A beginning charging rate that does not produce gassing or temperatures in excess of 110°F.

State of Charge
The amount of electrochemical energy left in a cell or battery.

Strap
Precast or cast-on piece of lead or lead alloy used to connect plates into groups and to connect groups to the post.

Strap Center
Spacing between centers of adjacent plates in a group.

Stratification
Layering of high specific gravity electrolyte in lower portions of a cell, where it does not circulate normally and is of no use.

Sulfated
A plate or cell whose active materials contain an appreciable amount of lead sulfate.

Sulfation
Formation of lead sulfate on a plate or cell as a result of discharge, self-discharge or pickling.

Sulfuric Acid
(H2SO4) The principal acid compound of sulfur, sulfuric acid in dilute and highly pure form is the electrolyte of lead acid storage cells.

Tack Burn
A shallow burn used to tack together two lead parts.

Tank Formation
Electrolytic processing of plates prior to assembly in large tanks of acid.

Temperature Correction
In storage cells, specific gravity and charging voltage vary inversely with temperature, while the open circuit voltage varies directly thought slightly with temperature.

Terminals
The points on a battery to which the external circuit is connected.

Terminal Cable
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 circuit.

Top Pour
A method of casting in which molten metal is poured, usually by hand, into a top gated mold.

Treeing
Growth of a lead dendrite or filament through a crack or hole of a separator, short-circuiting the cell.

Trickle Charge
A low-rate continuous charge approximately equal to a battery’s internal losses and capable of maintaining the battery in a fully-charged state.

TVR
A temperature compensating voltage relay used in charging equipment.

UL
Term for Underwriters’ Laboratories, a standards and testing agency for batteries that may be used in consumer applications in the U.S. There are a large number of standards for various consumer devices and anyone wishing to have batteries in these devices must first obtain UL approval.

Uncharged and Dry
The condition of a battery usually shipped to a customer, without electrolyte added. filling and a charge are necessary.

Undercharging
This is a situation where the charge put back into a battery after a discharge is not sufficient to fully charge it, given a certain amount of overcharge necessary for the product. It leads to rapid loss of capacity in cyclic duty and on float using too low a charge voltage can actually result in partial discharge of one or both plates during charge. Because of the tendency to treat them too delicately, undercharging is a common source of VRLA battery failure.

Unformed
A plate that has not been electrolytically formed.

UPS
The abbreviation of Uninterruptible Power Supply.

Useful Acid
The acid above the lower edges of the plates that takes part in the discharge reactions that occur within a cell.

Valve-regulated (Cell or Battery)
Term for a lead-acid battery employing oxygen recombination technology, either glass mat or gelled electrolyte, and which contains a pressure-relief valve to vent gases, primarily on overcharge. Common usage acronym is “VRLA”, standing for valve-regulated lead-acid. Formerly called sealed lead-acid. SLA.

Vent
Pressure-relief valve in a cell or battery that allows for the escape of gases at some release pressure but does not allow any level of gas ingress.

Vent Plug
The seal for the vent and filling well of a cell cover, containing a small hole for escape of gas.

Vent Well
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.

Verticals
The members or vertical bars of the members in a pasted plate grid.

Volt
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.

Volt Efficiency
The ratio for the average voltage of a cell or battery during discharge to the average voltage during subsequent recharge.

Voltage
The difference in electrical potential that exists between the terminals of a cell or battery or any two points of an electrical circuit.

Voltage Range
The difference between maximum and minimum cell voltages within a battery or string of cells when all cells are charging and discharging.

Voltmeter
An instrument for measuring voltage.

VRLA
Abbreviation of Valve Regulated Lead-Acid.

Watering
Adding water to battery electrolyte to replace loss from electrolysis and evaporation.

Watt
A unit of electric power, equal to a current of one ampere under one volt of pressure.

Watthour
a unit of electrical energy or work, equal to one watt acting for one hour.

Watthour Capacity
The number of watthours a storage battery can deliver under specific conditions of temperature, arte of discharge and final voltage.

Watthour Efficiency
A storage battery’s energy efficiency expressed as ratio of watthour output to the watthours of the recharge.

Watthour Meter
An electric motor that measures and registers electrical energy in watthours.

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.