Nine-volt battery

Historically, the now-popular PP3 battery size was a member of the power pack (PP) 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. In the 1940s, 1950s, and 1960s, they were commonly marketed as transistor radio batteries, or TR for short (meant to emulate the function of the old B battery). The PP3 battery was added as an ANSI standard in 1959, currently known as ANSI-1604A. The PP11 consists of two isolated 4.5-volt batteries with four terminals. Only the PP1, PP3, PP6, PP7, PP8/2, and PP9 sizes are still manufactured, with the PP3 being extremely common. Modern batteries have higher capacities and lower internal resistances than early versions. Before the mid-1950s, in the days of vacuum tube (valve) radios used batteries designed specifically for vacuum tubes, there was a nine-volt grid bias 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 transistors used in 1954 had to be operated very close to the collector-base junction voltage (VCBO) limit in order to get the required frequency response. However, a suitable miniature battery was already marketed for (vacuum tube) hearing aids. The PP3 (physically identical to 6LR61 and 1604A) appeared when portable transistor radios became common, and was referred to as a transistor battery or transistor-radio battery. ==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. ==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==

Battery chargers are devices that charge batteries, some of which may also be able to charge nine-volt batteries. Whether a charger can charge the battery depends largely on the dimensions of the battery and internal chemistry (I.E., disposable batteries cannot be charged). Testing a nine-volt battery can be done using a multi-meter by probing the voltage across the two terminals. The voltage measured by the multi-meter can then be used to roughly assess the charge of the battery. If the positive and negative terminals of the battery are close enough, licking a nine-volt battery can be a quick test to check if a battery has any charge left. A tingling sensation can be felt across the tongue depending on the voltage of the battery; The higher the current flowing through the tongue the more intense the tingling sensation. Although largely safe, some people may find the tingling sensation unpleasant. ==Lithium==

Lithium 9-volt batteries are rechargable 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 can be five times that of alkaline. Common applications for lithium nine-volt batteries are smoke and carbon monoxide detectors. ==See also==