A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

Alloy A mixture of several other metals or a metal and a non-metal. Alternator A type of generator used in automobiles to produce electric current.

Ampere-Hour Capacity
The quantity of electricity measured in ampere-hours (Ah) that may be delivered by a cell or battery under specified conditions.

Anode
The electrode in an electrochemical cell where oxidation takes place. During discharge, the negative electrode of the cell is the anode. During charge, the positive electrode is the anode.

Battery
A device for making or storing electricity chemically.

Battery Pack
Two or more electrochemical cells 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.

Bobbin
A cylindrical cell design utilizing an internal cylindrical electrode and an external electrode arranged as a sleeve inside the cell container.

C-Rate
Discharge 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 capacity is not the same at all discharge rates and usually increases with decreasing rate.)

Capacity
The total number of ampere-hours or watt-hours that can be withdrawn from a fully charged cell or battery under specified conditions of discharge.

Capacity Offset
A correction factor applied to the rating of a battery if discharged 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

Carbon/Zinc
A primary battery (non-rechargeable) commonly used in low drain consumer applications (i.e.: clocks, calculators, garage door openers, etc.). Available in the same sizes as the Alkaline and Manganese Dioxide (“AA”, “AAA”, 9volt, “C”, “D”) the Carbon/Zinc is one of the most widely used dry primary batteries because of its low cost and reliable performance.

Cathode
The electrode in an electrochemical cell 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.

Cell
The basic electrochemical unit used to generate or store electrical energy.

Cell Mismatch
Cells within a battery pack that contain different capacity and voltage levels.

Cell Reversal
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
The conversion of electrical energy, provided in the form of electrical current from an external source, to restore the chemical energy in a cell or battery.

Charge Control
Technique for effectively terminating the charging of a rechargeable battery.

Charging
Charge batteries with a DC current, positive terminal to positive terminal. The voltage must be greater than the battery or battery pack voltage. The current must be limited and the current cut off when the battery is fully charged.
Full charge is sensed either by a rise in voltage, a rise in resistance or a rise in temperature.
Battery chargers are designed to supply a suitable current for the batteries with which they where designed to work.
More sophisticated chargers will switch to a trickle when they sense the battery is fully charged. This is fine for Lead-Acid batteries but NiCd and NiMh should not be left on ‘maintenance’ charge for more than a few days.

The charging current is one eighth of the Ah (in Amps) or mAh (milliamps) rating of the battery. A full charge takes about 1.4 times the label capacity.
E.g. NiMh Battery 1800mAh capacity
Charging current 1800 divided by 8 = 225 mA
Charging time 1800 divided by 225 x 1.4 = 11.2 hours

Closed-circuit Voltage (CCV)
The potential or voltage of a battery when it is discharging or charging.

Condition
A process that utilizes a series of heavy discharges and recharges on a battery to assure optimum performance.

Constant Current
A battery discharge regime whereby the current drawn during the discharge. Discharge remains constant.

Constant Power
A battery discharge regime whereby the current during the discharge increases as the battery voltage decreases.

Constant Resistance
A battery discharge regime whereby the resistance of the equipment load remains constant throughout discharge.

Continuous Test
A test in which a battery is discharged to a prescribed point voltage without interruption.

Coulomb
The amount of electricity transported by a current of one ampere flowing for one second.

Current
The rate at which (a volume of) electricity moves through a (pipe) conductor. Measured in Amps.
The potential is measured in (height) volts.

Current Collector
An inert structure of high electrical conductivity used to conduct current from or to an electrode during discharge or charge.

Current Density
The current per unit active area of the surface of an electrode.

Current Drain
The current withdrawn from a battery during discharge.

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 chargers).

Cutoff Voltage
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.

Cycle
A sequence where a charged battery is discharged and recharged.

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.

Cylindrical Cell
The positive and negative plates are rolled up and placed into a cylindrical container (as opposed to stacking the plates in a prismatic cell design).

Depth of Discharge
The ratio of the quantity of electricity (usually in ampere-hours) removed from a battery to its rated capacity.

Desorption
The opposite of absorption, whereby the material retained by a medium or another material is released.

Direct Current
Electrical current that flows in one direction only. Batteries produce direct current as the current flows from a negative to a positive source.

Discharge
The conversion of the chemical energy of a battery into electrical energy, and the withdrawal of the electrical energy into a load.

Discharge Rate
The rate, usually expressed in amperes, at which electrical current is taken from the battery.

Disposal
Never burn any battery, it may explode, it will release caustic electrolyte, and it may distribute harmful metal oxide particles.
Batteries containing silver, cadmium and mercury must have special disposal or may be returned.
Lithium batteries containing more than 0.5gram of Lithium metal present a special hazard.
Alkaline, NiMh, Zinc-Air, small Li-ion and Lithium coin cells, and conventional torch batteries can go in domestic waste.

Drain
The current withdrawn from a battery during discharge.

Dry Cell
A cell with immobilized electrolyte. The term "dry cell" is often used to describe the Leclanche cell.

Duty Cycle
The operating regime of a battery including factors such as charge and discharge rates, depth of discharge, cycle duration, and length of time in the standby mode.


E-Rate
Discharge 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.)

Electric Current
The movement of electrons along a conductor.

Electrochemical Equivalent
Weight of a substance that is deposited at an electrode when the quantity of electricity which is passed is one coulomb

Electrode
The site, area or location at which electrochemical processes take place.
The raised Positive pip on a torch battery is connected to the battery Cathode; the flat end is connected to negative Anode.
In a Lead-Acid battery -car battery- Lead is the anode and acid -sulfuric acid, battery acid- the electrolyte. Lead Dioxide is the cathode.
In a NiCd, Nickel-Cadmium, battery Nickel is the anode and Cadmium the cathode.

Electrolyte
The medium which provides the ion transport mechanism between the positive and negative electrodes of a cell.

Electron
Negatively charged particle that orbits the nucleus of an atom.

End Voltage Cutoff
The prescribed voltage at which the discharge (or charge, if end-of-charge voltage) of a battery may be considered complete.

Energy
The output capability of a cell or battery, usually expressed in watt-hours.

Energy Density
The ratio of the energy available from a battery to its volume (Wh/L) or weight (Wh/kg).

Fast Charge
Typical fast charge time for a NiCd is 1 to 3 hours. The fast-charger detects the state of charge and switches to trickle charge when full-charge is reached.

Float
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 backup.

Float Charge
Similar to trickle charge. Compensates for the self-discharge on a SLA battery

Forced Discharge
Discharging a cell in a battery, by the other cells or an external power source, below zero volts into voltage reversal.

Fuse
Device used for cutting off an electrical current in the event of an abusive condition.

Fuel Cell
A battery that makes electric current from mechanically or continually replaced electrodes. E.g. Hydrogen/ oxygen cells proposed for electric cars. Not generally available off-the-shelf.
Instead of burning the fuel to make heat, the fuel cell makes electricity.

Gassing
The evolution of gas from one or more of the electrodes in a cell. Gassing commonly results from local action (self-discharge) or from the electrolysis of water in the electrolyte during charging.

Generator
A device that produces an electric current through magnetism.

Gravimetric Energy
The ratio of the energy output of a cell or battery to its weight (Wh/kg). This term is used interchangeably with specific energy.

Ground
To connect to the earth or some conductor which takes the place of the earth.

Hazardous Waste
Waste which is classified as "hazardous" (i.e.. potentially harmful to the environment) by the government.

Hertz (Hz)
The standard unit of frequency. A frequency of one complete cycle per second is a frequency of one hertz.

Hourly Rate
A discharge rate, in amperes, of a battery which will deliver the specified hours of service to a given cutoff voltage.

Hydrometer
A device used to measure the specific gravity of the electrolyte in a cell.

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 regime.

Internal Impedance
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 components.
When a battery is connected to a circuit to do work, the current in the circuit is in inverse proportion to the resistance of the circuit plus the internal resistance of the battery. This can lead to the batteries becoming warm.

IR Drop
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 (in ohms).

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) Gel/Gel Cell Sealed Lead Acid.

LeClanche Battery
Zinc-Carbon batteries. Pre Alkaline torch batteries. In the lofts of old house there are often open topped glass jars that used to have a carbon and zinc rod with ammonium chloride solution as an electrolyte, to make a wet cell battery that powered the door bell. 1.5 volts. Still made as a dry battery.

Li-Ion - Lithium Ion
One of the newer rechargeable battery technologies, Li Ion batteries can deliver 40% more capacity than comparably sized NiCd batteries and are one of the lightest rechargeable batteries available today. Li Ion batteries are the batteries of choice in notebook computers, wireless telephones and many camcorder models. They are also one of the more expensive rechargeable technologies.
3.6 volts per cell. Lightweight, high capacity, expensive batteries.
Not that much difference in capacity for the same volume as NiMh, but significantly lighter.
Li-Ion batteries can be 'Top Up' charged- recharged at any convenient time, without waiting for the battery to be completely discharged. For storage- store them as they are and allow them to self discharge slowly. Recharge them fully again when you want to use them.

Li-Po - Lithium Polymer
A battery technology similar to Lithium-Ion.
Current “lithium-polymer” batteries are technically “Lithium Ion Polymer”, since pure lithium-polymer batteries are not yet commercially viable. Pure lithium-polymer batteries, once available, will theoretically provide considerable benefits over current battery technologies.
Today’s lithium-ion polymer batteries perform similarly to lithium-ion batteries, but can be made much thinner – as thin as 1mm.

Lithium
A primary battery (non-rechargeable) that is quickly entering mainstream electronic designs, particularly in consumer, portable equipment and non-volatile memory back up applications where small size, long life and low cost are the primary requirements. Lithium batteries have superior cold temperature performance and a shelf life of 5-10 years.
The 3rd element, after Hydrogen and Helium. This position at one of the extremes gives it some interesting properties. Very different types of battery are made containing Lithium; some are rechargeable some are not; some are safe, some are not.

Lithium Coin or Button Cells
Lithium-Manganese Dioxide coin cells. Zinc-Manganese Dioxide -Alkaline- cells are made in the same sizes. The Lithium cells have a larger capacity and voltage. Often interchangeable.†
Not rechargeable. Never try to recharge.
3 to 3.6 volts nominal per cell.
Less than 0.5 grams Lithium per cell.
Better tolerance of temperature extremes than other domestic batteries. -50 Deg. C to +70 Deg. C.
Long shelf life -10years+. Long life in low drain service.

Load Current
The discharge current provided by a battery, or drawn by a battery powered device.

Magnesium Battery
Magnesium batteries are used in sea going safety equipment. They are made without an electrolyte. When immersed in sea water, the salty water acts as an electrolyte and they produce power. They have a good, but finite, shelf life even in humid conditions. Once activated they must be replaced.

Manganese Dioxide
A primary battery (non-rechargeable) similar to that of the alkaline battery though not as strong in total energy. Available in the same size as Alkaline and Carbon/Zinc ("AA", "AAA", "C","D", 9volt) the Manganese Dioxide chemistry is noted for its ability to retain its charge while being stored at high temperatures and operates well at temperatures as low as -40_C with little loss of capacity.

Memory Effect
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.

Some rechargeable batteries are said to have a memory. If they are part-used and recharged before the whole charge is used up, they ‘remember’ this and next time will only use that part of their capacity. Therefore part of their capacity is lost. This is the theory, it is much debated.
NiCd and NiMh batteries are said to suffer from memory effect.
NiCd and NiMh batteries prefer complete cycles; fully charge then use until empty, do not recharge before storage - allow them to self-discharge during storage.
In the real world, either of these batteries will accept less than the ideal and provided that they are recycled completely, full to empty, reasonably often they will put up with what comes in between.
NiMh batteries have less memory effect than NiCd.

Mercury
Good batteries have been made using Mercury. These are not now in general use, because of potential pollution. Silver-Oxide or Zinc-Air cells make good or superior alternatives.

Metal Hydride
An inter-metallic compound or alloy in which hydrogen has been absorbed-, also, the negative electrode in a nickel-metal hydride battery.

Midpoint Voltage
The voltage of a battery midway in the discharge between the start of the discharge and the end voltage.

MilliAmps
Refers to battery capacity. A 1/1000th of an amp, e.g.: 1.0Ah = 1000mAh.

Negative
A terminal or electrode which has an excess of electrons.

NiCd - Nickel Cadmium
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 power tools.
Due to the Cadmium content this battery must be disposed of safely. NiCd batteries have gained a bad reputation for their memory effect.

NiCd batteries prefer to be charged when they show a drop in power (to over-discharge a battery pack risks ‘voltage reversal’, of the weakest cell).
Store as they are, and recharge before use.
NiCd batteries self-discharge. They lose about 40% of their charge in 4 weeks.
NiCd batteries have a low internal resistance:
They can deliver a high current
They don’t overheat easily in use
They can be charged quickly.
Used sensibly they have a life span twice that of NiMh or Li-ion batteries.
1.2 volts per cell, reasonably constant over the discharge cycle.

NiMh - Nickel Metal Hydride
Interchangeable with most NiCd batteries, nickel metal hydride (NiMh) batteries generally deliver 10-25% greater capacity than NiCd’s and are environmentally more friendly than NiCd’s since they do not contain cadmium. Used in many wireless phone and camcorders.
Nickel Metal Hydride. In some ways a successor to NiCd batteries, in some ways still inferior.
No special disposal necessary.
Increased capacity.
Less ‘memory effect’.
Slower charging - a Fast NiCd charger, one of less than 8 hours is generally unsuitable.

Nominal Voltage
The characteristic operating voltage or rated voltage of a battery.

Ohm
A measure of resistance that causes one volt to produce a current of one ampere.

Open-Circuit Voltage
The difference in potential between the terminals of a cell when the circuit is open (no-load condition).

Overcharge
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.

Over-discharge
The process of discharging a cell or battery beyond its cutoff voltage and possibly into voltage reversal.

Parallel
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 (sum of the total). NiCd, NiMh and Lithium cells should not be connected in parallel.


Primary Battery
A battery which is not intended to be recharged and is discarded when the battery has delivered all of its electrical energy.

Passivation
The phenomenon by which a metal, although in conditions of thermodynamic instability, remains indefinitely un-attacked because of modified or altered surface conditions.

Polarity
In electricity, the condition of being positive or negative.

Polarization
The lowering of the potential of a cell or electrode from its equilibrium value caused by the passage of an electric current.

Positive
A terminal or electrode which has a shortage of electrons.

Positive Temperature
A thermally reactive device which becomes highly resistive at a specific Coefficient (PTC) temperature or current.

Prismatic Cell
The positive and negative plates are stacked rather than rolled as done in a cylindrical cell.

Pulse Current
A periodic current drain of higher than normal drain rates.

Rapid Charge
A charge time that is between slow charge and fast charge (typically 3 to 6 hours for a NiCd).

Rated Capacity
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.

Rechargeable battery
A galvanic 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.

Recondition
One or more deep discharge cycles below 1.0 volt/cell at a very low, controlled current. Recondition helps to revert large crystals to small desirable sized, often restoring the battery to it's full capacity.

Replacing Batteries
Always replace all the batteries in a circuit if you replace any. Never connect different types of battery together. The stronger batteries can reverse the polarity of the weaker. There is a small risk of rupturing a cell.
Check the terminals are clean and making good contact.
Put the batteries in the right way round.
Raised Pip to the + or red terminal.
Nose to tail, the pip of one battery to the base of the next.
Often a coil spring pushes on the base of the battery and a flat contact connects to the pip.

Resistance
The degree to which the flow of electrons is opposed by the material the electrons must pass through. Resistance is expressed in Ohms.

Reversal
The changing of the normal polarity of a battery due to over-discharge.


Safety Vent
A venting mechanism designed into a cell which activates under specific conditions of abuse to relieve internal pressure.

Sealed Lead Acid Batteries
2.0 volts per cell
The Sealed Lead Acid battery is the traditional wet cell car battery, re-designed as a dry battery. The electrolyte is gelled and absorbed onto a glass fiber mat, and the areas of the anode and cathode greatly increased. Although the cost of manufacture is higher, sealed lead acid batteries or “gel cells” have a longer life, higher capacity and are safer than wet cells.
These batteries must be stored in a charged condition, they self-discharge at a moderate rate. Therefore they should be re-charged at least once a year to remain in good condition, even if only stored.
You can replace a wet Lead Acid battery with a Sealed Lead Acid battery, of similar capacity without altering the circuit or charging circuit.
SLA batteries can evolve Hydrogen and Oxygen whilst being charged. These gases form an explosive mixture. Allow ventilation to batteries whilst charging.

Secure Waste Landfill
A landfill designed for disposal of normal household trash but which meets government standards designed to protect the environment.

Self-Discharge
The loss of useful capacity of a battery on storage due to internal chemical action (local action).
Batteries, stored, unused, lose their charge (age), slowly with time.
The rate of self-discharge depends on the type of battery. Alkaline batteries and most primary batteries have a good shelf life - they self-discharge very slowly.
The rate of self-discharge rises rapidly with temperature, the ideal storage temperature is between 4 and 15 Deg. centigrade.

Separator
An ionic permeable electronically non-conductive spacer or material which prevents electronic contact between electrodes of opposite polarity in the same cell.

Series
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.  The cells should always be similar cells. Never replace one cell in a series, always the lot.
The battery pack is only as good as the weakest cell. See Parallel

Service Life
The period of useful life of a battery before a predetermined end-point voltage is reached.

Shelf Life
The duration of storage under specified conditions at the end of which the battery still retains the ability to give a specified performance.

Short Circuit
An unwanted electrical connection between a negative and positive source. Short circuits can damage the battery and equipment and can cause sparks or fire.

Short-circuit Current
The initial value of the current obtained from a battery in a circuit of negligible resistance.

Silver/Oxide
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.

Slow Charge
Typically an over-night charge lasting abut 14 hours at a charge current of 0.1C. Battery does not require instant removal when fully charged.

Smart Battery
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 intelligent charger.

Specific Energy
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.

Spiral Wound
An electrode structure of high surface area created by winding the electrodes and separator into a spiral-wound jelly-roll configuration.

Standby
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.

State of Charge
The capacity remaining in a battery.

Sulfation
Growth of lead sulfate crystals in Lead-Acid batteries which inhibits current flow. Sulfation is caused by storage at low state of charge.

Tag
When rechargeable cells are assembled into a battery pack, they are connected in series by tags welded to the battery. In large-scale production the connections may all be welded without any soldered joints. This gives joints with the lowest resistance. On a small scale, or when the currents are lower or in repair work soldering to tags is much easier than soldering on to a battery.

Temperature
Common batteries like the same temperatures as humans. They won’t work well in low temperatures. High temperatures shorten their life.
This factor needs careful consideration if batteries are going to be relied upon in an emergency.
Store at max. 25C, preferably less. A camera battery in a black case in the sun or a lead-acid battery in a greenhouse will have a shorter life.
Special batteries are made for other temperature ranges. Lithium batteries perform best of the common batteries. NiMh cells with their higher internal resistance are more at risk than NiCd cells.

Temperature Cutoff
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.

Thermistor
A temperature sensitive resistor usually made from specially processed oxides that are used to sense end of charge temperature rises and terminates high rate charging.

Thermostat
A temperature sensitive switch.

Top-Up Charge
A low rate charge following the main charge, designed to ensure maximum capacity.

Trickle Charge
A charge at a low rate, balancing losses through local action and/or periodic discharge, to maintain a cell or battery in a fully charged condition.

UPS
Uninterruptible Power Supply Units:
Keep a computer and its data safe and running what ever happens to the power supply - lightning, voltage drop or droop, surge, fuse blown or supply cut can be programmed to save current work and close down after a set number of minutes protect the phone and computer from surges induced by lightning in the phone line correct the power from a local generator- including 110 volts AC.
Also capable of protecting Fax machines or any other essential equipment.

Vent
If a current passes through a cell, gases can be evolved. The internal pressure could rupture the cell if it is sealed. Most dry cells are fitted with a vent to relieve this pressure. The vent automatically reseals. This is why Sealed Lead acid batteries should be charged upright.

Voltage
A unit of measuring electrical pressure, all batteries are rated in volts DC (Direct Current).
The voltage of Alkaline batteries droops in a curve during its life.
Lead-Acid, Zinc-Air, Silver-Oxide and NiCd batteries have a much more constant voltage - a ‘flat’ discharge/time curve.

Voltage Depression
An abnormal drop in voltage below expected values during the discharge of a battery.

Voltage Delay
Time delay for a battery to deliver the required operating voltage after it is placed under load.

Voltage-Keyed
A system that incorporates a mechanical identifier on batteries and devices to ensure only batteries of the correct voltage are connected to the device.

Voltage Regulator
A device that regulates the output of a generator or alternator by controlling the current and voltage.

Voltage Reversal
The changing of the normal polarity of a battery due to over-discharge.

Volumetric Energy Density
The ratio of the energy output of a cell or battery to its volume (Wh/L).

Watts
A measurement of energy, arrived at by multiplying the voltage by the amperage.

Watt Hours
A common measurement of energy produced in a given amount of time, arrived at by multiplying the voltage by the amp-hours.

Watch Batteries
Although various chemistries have been used, most batteries are Silver-Oxide with Alkaline as a low cost alternative.

Zinc-Air
A primary battery (non-rechargeable) that was commonly used for applications such as watches and hearing aids. In relation to their physical size, Zinc/Air batteries store more energy per unit of weight (in terms of 220 W h/kg) than any other primary type.