The nine-volt battery, or 9-volt battery, is an

electric battery An electric battery is a source of electric power consisting of one or more electrochemical cells with external connections for powering electrical devices. When a battery is supplying power, its positive terminal is the cathode and its neg ...

that supplies a nominal voltage of 9

volt The volt (symbol: V) is the unit of electric potential, electric potential difference (voltage), and electromotive force in the International System of Units (SI). It is named after the Italian physicist Alessandro Volta (1745–1827). Defin ...

s. Actual voltage measures 7.2 to 9.6 volts, depending on battery chemistry. Batteries of various sizes and capacities are manufactured; a very common size is known as PP3, introduced for early

transistor radio A transistor radio is a small portable radio receiver that uses transistor-based circuitry. Following the invention of the transistor in 1947—which revolutionized the field of consumer electronics by introducing small but powerful, convenient ...

s. The PP3 has a rectangular prism shape with rounded edges and two polarized snap connectors on the top. This type is commonly used for many applications including household uses such as

smoke Smoke is a suspension of airborne particulates and gases emitted when a material undergoes combustion or pyrolysis, together with the quantity of air that is entrained or otherwise mixed into the mass. It is commonly an unwanted by-produc ...

and

gas detector A gas detector is a device that detects the presence of gases in an area, often as part of a safety system. A gas detector can sound an alarm to operators in the area where the leak is occurring, giving them the opportunity to leave. This type of ...

clock A clock or a timepiece is a device used to measure and indicate time. The clock is one of the oldest human inventions, meeting the need to measure intervals of time shorter than the natural units such as the day, the lunar month and ...

s, and toys. The nine-volt PP3-size battery is commonly available in primary zinc-carbon and

alkaline In chemistry, an alkali (; from ar, القلوي, al-qaly, lit=ashes of the saltwort) is a basic, ionic salt of an alkali metal or an alkaline earth metal. An alkali can also be defined as a base that dissolves in water. A solution of a ...

chemistry, in primary lithium iron disulfide and lithium manganese dioxide (sometimes designated CRV9 9-volt batteries supplied by a typical distributor: PP3 (or CRV9), PP6, PP7, and PP9 are the PP sizes; A10 and A29 the only other 9v types.), and in rechargeable form in nickel-cadmium (Ni–Cd), nickel-metal hydride (Ni–MH) and

lithium-ion A lithium-ion or Li-ion battery is a type of rechargeable battery which uses the reversible reduction of lithium ions to store energy. It is the predominant battery type used in portable consumer electronics and electric vehicles. It also ...

. Mercury batteries of this format, once common, have been banned in many countries due to their toxicity. Designations for this format include ''NEDA 1604'' and ''IEC 6F22'' (for zinc-carbon) or ''MN1604 6LR61'' (for alkaline). The size, regardless of chemistry, is commonly designated PP3—a designation originally reserved solely for carbon-zinc, or in some countries, ''E'' or ''E-block''. A range of PP batteries was produced in the past, with voltages of 4.5, 6, and 9 volts and different capacities; the larger 9-volt PP6, PP7, and PP9 are still available. A few other 9-volt battery sizes are available: A10 and A29. Most PP3-size alkaline batteries are constructed of six individual 1.5 V LR61 cells enclosed in a wrapper.IEC 60086-2-2011 §7.6.1.12 These cells are slightly smaller than LR8D425 AAAA cells and can be used in their place for some devices, even though they are 3.5 mm shorter. Carbon-zinc types are made with six flat cells in a stack, enclosed in a moisture-resistant wrapper to prevent drying. Primary lithium types are made with three cells in series. 9-volt batteries accounted for 4% of alkaline

primary battery A primary battery or primary cell is a battery (a galvanic cell) that is designed to be used once and discarded, and not recharged with electricity and reused like a secondary cell ( rechargeable battery). In general, the electrochemical react ...

sales in the United States in 2007, and 2% of primary battery sales and 2% of secondary (rechargeable) battery sales in Switzerland in 2008.

History

Historically, the now popular PP3 battery size was a member of the PP (

Power Pack Power Pack is a superhero team consisting of four young siblings appearing in American comic books published by Marvel Comics. Created by writer Louise Simonson and artist June Brigman, they first appeared in their own series in 1984, which last ...

) battery family that was originally manufactured by Ever Ready in the United Kingdom and Eveready in the United States. The company says that it introduced the PP3 battery in 1956, having been added as an

ANSI The American National Standards Institute (ANSI ) is a private non-profit organization that oversees the development of voluntary consensus standards for products, services, processes, systems, and personnel in the United States. The organi ...

standard in 1959, currently known as ANSI-1604A. The PP11 consists of two isolated 4.5-volt batteries with four terminals. Only the PP3, PP6, PP7 and PP9 sizes are still manufactured, with the PP3 being extremely common. Modern batteries have higher capacity and lower internal resistance than early versions. Before the mid-1950s, in the days of

vacuum tube A vacuum tube, electron tube, valve (British usage), or tube (North America), is a device that controls electric current flow in a high vacuum between electrodes to which an electric potential difference has been applied. The type known as ...

(valve)

radios Radio is the technology of signaling and communicating using radio waves. Radio waves are electromagnetic waves of frequency between 30 hertz (Hz) and 300 gigahertz (GHz). They are generated by an electronic device called a transmitt ...

used batteries designed specifically for vacuum tubes, there was a nine-volt

grid bias In electronics, biasing is the setting of DC (direct current) operating conditions (current and voltage) of an active device in an amplifier. Many electronic devices, such as diodes, transistors and vacuum tubes, whose function is processing ...

battery or (US) "C" battery, which had taps for various voltages from 1.5 to 9 volts. Early transistorized radios and other equipment needed a suitable voltage miniature battery. Early transistor radios required a volt battery. Although the transistors would theoretically operate from lower voltages, the

point-contact transistor The point-contact transistor was the first type of transistor to be successfully demonstrated. It was developed by research scientists John Bardeen and Walter Brattain at Bell Laboratories in December 1947. They worked in a group led by physici ...

s used in 1954 had to be operated very close to their V_CB0 limit in order to get the required frequency response. However, a suitable miniature battery was already marketed for (vacuum tube)

hearing aid A hearing aid is a device designed to improve hearing by making sound audible to a person with hearing loss. Hearing aids are classified as medical devices in most countries, and regulated by the respective regulations. Small audio amplifiers s ...

s. The PP3 (physically identical to 6LR61 or 1604A) appeared when portable transistor radios became common, and is still called a "transistor" battery by some manufacturers.

PP3 connectors

The PP3 battery has both terminals in a snap connector on one end. The smaller circular (male) terminal is positive, and the larger hexagonal or octagonal (female) terminal is the negative contact. The connectors on the battery are the same as on the load device; the smaller one connects to the larger one and vice versa. The same snap-style connector is used on other battery types in the

(PP) series. Battery polarization is normally obvious, since mechanical connection is usually only possible in one configuration. A problem with this type of connector is that two loose batteries with terminals exposed can touch and

short circuit A short circuit (sometimes abbreviated to short or s/c) is an electrical circuit that allows a current to travel along an unintended path with no or very low electrical impedance. This results in an excessive current flowing through the circu ...

, discharging them, and generating heat and possibly a fire. Keeping nine-volt batteries in their packaging until use helps to avoid accidental discharge.

Technical specifications

Very often, a "9-volt" battery refers to the transistor radio size called PP3 or IEC 6F22 or NEDA 1604, although there are less common nine-volt batteries of different sizes. Batteries of all types are manufactured in consumer and industrial grades. Costlier industrial-grade batteries may use chemistries that provide higher power-to-size ratio, have lower self-discharge and hence longer life when not in use, more resistance to leakage and, for example, ability to handle the high temperature and humidity associated with medical autoclave sterilization.

Testing and charging

Most battery voltage testers and chargers that can also test nine-volt need another snap clip to hold the battery, while cylindrical batteries often share a holder that may be adjustable in size. Because of the proximity of the positive and negative terminals at the top of the battery and relatively low current of most common batteries, one informal method of testing voltage is to place the two terminals across a tongue. A strong tingle would indicate a battery with a strong charge, the absence, a discharged battery. While there have been stories circulating of unfortunate outcomes, the process is rarely dangerous under normal circumstances, though it may be unpleasant.

Lithium

Lithium Lithium (from el, λίθος, lithos, lit=stone) is a chemical element with the symbol Li and atomic number 3. It is a soft, silvery-white alkali metal. Under standard conditions, it is the least dense metal and the least dense soli ...

9-volt batteries are disposable high-energy-density batteries. In the PP3 size they are typically rated at 0.8–1.2 Ah (e.g. >1.2 Ah @ 900 ohms to 5.4 V @ 23 °C for one type), about twice the capacity of alkaline batteries. Some manufacturers claim the

energy density In physics, energy density is the amount of energy stored in a given system or region of space per unit volume. It is sometimes confused with energy per unit mass which is properly called specific energy or . Often only the ''useful'' or extrac ...

can be five times that of alkaline. Common applications for lithium nine-volt batteries are

and

carbon monoxide detector A carbon monoxide detector or CO detector is a device that detects the presence of the carbon monoxide (CO) gas to prevent carbon monoxide poisoning. In the late 1990s Underwriters Laboratories changed the definition of a single station CO d ...

Notes

References

External links

* {{Portal bar, Energy, Electronics Battery shapes