Reserve battery
Encyclopedia
A reserve battery, also called stand-by battery, is a primary battery where part is isolated until the battery needs to be used. When long storage is required, reserve batteries are often used, since the active chemicals of the cell are segregated until needed, thus reducing self-discharge
.
A reserve battery is distinguished from a backup battery
, in that a reserve battery is inert until it is activated, while a backup battery is already functional, even if it is not delivering current.
s, missile
s, projectile
and bomb
fuze
s, and various weapon system
s.
While not advertised as reserve batteries, the principle is illustrated by the sale of "dry charged" car batteries
where the electrolyte is added at the time of sale. Another example is zinc-air batteries
where the cell is sealed until use: a tab is removed to admit air and activate the cell.
, by introducing a gas into the cell that is either the active cathode material or part of the electrolyte, or by heating a solid electrolyte to a temperature at which is becomes conductive. The missing element of the battery can be added before use in several ways. The battery can have water or electrolyte added manually, the battery can be activated when the system is dropped into the water (such as in a sonobuoy
), or electrolyte can be stored in a capsule within the battery and released by mechanical means, an electrical trigger, or by spin or shock. A molten-electrolyte battery
is activated by igniting a pyrotechnic heat source
. The battery delivers current for a short time (seconds to a few minutes), but some thermal batteries can be stored 10 years or more without deterioration. Reserve batteries remain uncommon in civilian applications because of their higher cost and relatively short life after activation.
In missiles, reserve batteries typically use a small container of pressurized air to force the electrolyte from storage tank into the battery. For safe disposal, the air must be vented. This led to use of the term "venting" for preparing of any kind of battery for disposal, whether draining electrolyte from lead cells or full discharge of lithium batteries.
In ordnance, the batteries are activated by acceleration during gun firing, or by spinning the projectile in flight.
Self-discharge
Self-discharge is a phenomenon in batteries in which internal chemical reactions reduce the stored charge of the battery without any connection between the electrodes...
.
A reserve battery is distinguished from a backup battery
Backup battery
A backup battery provides power to a system when the primary source of power is unavailable. Backup batteries range from small single cells to retain clock time and date in computers, up to large battery room facilities that power uninterruptible power supply systems for large data centers...
, in that a reserve battery is inert until it is activated, while a backup battery is already functional, even if it is not delivering current.
Uses
These batteries are used in radiosondeRadiosonde
A radiosonde is a unit for use in weather balloons that measures various atmospheric parameters and transmits them to a fixed receiver. Radiosondes may operate at a radio frequency of 403 MHz or 1680 MHz and both types may be adjusted slightly higher or lower as required...
s, missile
Missile
Though a missile may be any thrown or launched object, it colloquially almost always refers to a self-propelled guided weapon system.-Etymology:The word missile comes from the Latin verb mittere, meaning "to send"...
s, projectile
Projectile
A projectile is any object projected into space by the exertion of a force. Although a thrown baseball is technically a projectile too, the term more commonly refers to a weapon....
and bomb
Bomb
A bomb is any of a range of explosive weapons that only rely on the exothermic reaction of an explosive material to provide an extremely sudden and violent release of energy...
fuze
Fuze
Fuze Beverage, commercially referred to as just Fuze , is a manufacturer of teas and non-carbonated fruit drinks enriched with vitamins. Currently the brand consists of five vitamin-infused lines: Slenderize, Refresh, Tea, Defensify, and Vitalize...
s, and various weapon system
Weapon system
Weapon System is a United States military term that designated, along with a weapon system number , military experimental systems prior to official naming Weapon System is a United States military term that designated, along with a weapon system number (e.g., WS-110), military experimental (MX)...
s.
While not advertised as reserve batteries, the principle is illustrated by the sale of "dry charged" car batteries
Car battery
An automotive battery is a type of rechargeable battery that supplies electric energy to an automobile. Usually this refers to an SLI battery to power the starter motor, the lights, and the ignition system of a vehicle’s engine...
where the electrolyte is added at the time of sale. Another example is zinc-air batteries
Zinc-air battery
Zinc–air batteries , and zinc–air fuel cells, are electro-chemical batteries powered by oxidizing zinc with oxygen from the air. These batteries have high energy densities and are relatively inexpensive to produce...
where the cell is sealed until use: a tab is removed to admit air and activate the cell.
Activation
Reserve batteries may be activated by addition of water, by adding electrolyteElectrolyte
In chemistry, an electrolyte is any substance containing free ions that make the substance electrically conductive. The most typical electrolyte is an ionic solution, but molten electrolytes and solid electrolytes are also possible....
, by introducing a gas into the cell that is either the active cathode material or part of the electrolyte, or by heating a solid electrolyte to a temperature at which is becomes conductive. The missing element of the battery can be added before use in several ways. The battery can have water or electrolyte added manually, the battery can be activated when the system is dropped into the water (such as in a sonobuoy
Sonobuoy
A sonobuoy is a relatively small expendable sonar system that is dropped/ejected from aircraft or ships conducting anti-submarine warfare or underwater acoustic research....
), or electrolyte can be stored in a capsule within the battery and released by mechanical means, an electrical trigger, or by spin or shock. A molten-electrolyte battery
Molten salt battery
Molten salt batteries or liquid sodium battery are a class of primary cell and secondary cell high-temperature electric battery that use molten salts as an electrolyte. They offer both a higher energy density through the proper selection of reactant pairs as well as a higher power density by means...
is activated by igniting a pyrotechnic heat source
Pyrotechnic heat source
A pyrotechnic heat source, also called heat pellet, is a pyrotechnic device based on a pyrotechnic composition with a suitable igniter. Its role is to produce controlled amount of heat...
. The battery delivers current for a short time (seconds to a few minutes), but some thermal batteries can be stored 10 years or more without deterioration. Reserve batteries remain uncommon in civilian applications because of their higher cost and relatively short life after activation.
In missiles, reserve batteries typically use a small container of pressurized air to force the electrolyte from storage tank into the battery. For safe disposal, the air must be vented. This led to use of the term "venting" for preparing of any kind of battery for disposal, whether draining electrolyte from lead cells or full discharge of lithium batteries.
In ordnance, the batteries are activated by acceleration during gun firing, or by spinning the projectile in flight.
Types
Some reserve batteries are:- Aluminium batteryAluminium batteryAluminium–air batteries or Al–air batteries produce electricity from the reaction of oxygen in the air with aluminium. They have one of the highest energy densities of all batteries, but they are not widely used because of previous problems with cost, shelf-life, start-up time, and byproduct...
, a variant to zinc-air batteryZinc-air batteryZinc–air batteries , and zinc–air fuel cells, are electro-chemical batteries powered by oxidizing zinc with oxygen from the air. These batteries have high energy densities and are relatively inexpensive to produce...
where aluminium and air are used - Silver-zinc battery, often found in old missiles
- Thermal battery, a class of battery types with molten saltMolten salt batteryMolten salt batteries or liquid sodium battery are a class of primary cell and secondary cell high-temperature electric battery that use molten salts as an electrolyte. They offer both a higher energy density through the proper selection of reactant pairs as well as a higher power density by means...
as an electrolyte. The battery is in an inert state until the electrolyte melts through heating. Common in military applications, especially for missiles and proximity fuzeProximity fuzeA proximity fuze is a fuze that is designed to detonate an explosive device automatically when the distance to target becomes smaller than a predetermined value or when the target passes through a given plane...
s Applications include V-2 rocketV-2 rocketThe V-2 rocket , technical name Aggregat-4 , was a ballistic missile that was developed at the beginning of the Second World War in Germany, specifically targeted at London and later Antwerp. The liquid-propellant rocket was the world's first long-range combat-ballistic missile and first known...
s, AIM-9 SidewinderAIM-9 SidewinderThe AIM-9 Sidewinder is a heat-seeking, short-range, air-to-air missile carried mostly by fighter aircraft and recently, certain gunship helicopters. The missile entered service with United States Air Force in the early 1950s, and variants and upgrades remain in active service with many air forces...
, MIM-104 PatriotMIM-104 PatriotThe MIM-104 Patriot is a surface-to-air missile system, the primary of its kind used by the United States Army and several allied nations. It is manufactured by the Raytheon Company of the United States. The Patriot System replaced the Nike Hercules system as the U.S. Army's primary High to Medium...
, BGM-71 TOWBGM-71 TOWThe BGM-71 TOW is an anti-tank missile. "BGM" is a weapon classification that stands for "Multiple Environment , Surface-Attack , Missile ". "TOW" is an acronym that stands for "Tube-launched, Optically-tracked, Wire command data link, guided missile"...
, BGM-109 TomahawkBGM-109 TomahawkThe Tomahawk is a long-range, all-weather, subsonic cruise missile. Introduced by General Dynamics in the 1970s, it was designed as a medium- to long-range, low-altitude missile that could be launched from a surface platform. It has been improved several times and, by way of corporate divestitures...
, many nuclear weapons, and other single-use applications. - Water-activated batteryWater-activated batteryA water-activated battery is a disposable reserve battery that does not contain an electrolyte and hence produces no voltage until it is soaked in water for several minutes.-Description:...
, a class of batteries where the electrolyte is water that has to be added, such as HydroPak or NoPoPo.