Nine-volt battery

Duracell PP3 (9 volt) battery

Collage of images showing the opening of a 9-volt battery to reveal six LR61 size cells, which are similar to the LR8D425 AAAA cells often used in medical equipment.

Three different kinds of 9-volt primary battery internals.

Rechargeable (NiMH) 9-volt battery internals.

A nine-volt battery, the most common of which (and the one referred to here unless otherwise stated) is designated a PP3 battery, is shaped as a rounded rectangular prism. 9-volt batteries are commonly used in pocket transistor radios, smoke detectors, carbon monoxide alarms, guitar effect units, and radio-controlled vehicle controllers. They are also used as backup power to keep the time in digital clocks and alarm clocks.

Nine-volt alkaline batteries are constructed of six individual 1.5V LR61 cells enclosed in a wrapper. ^[1] These cells are slightly smaller than standard LR8D425 AAAA cells and can be used in their place for some devices, even though they are 3.5 mm shorter.

As of 2007, 9-volt batteries accounted for 4% of alkaline primary battery sales in the US. In Switzerland as of 2008, 9-volt batteries totalled 2% of primary battery sales and 2% of secondary battery sales. ^{[2] [3]}

Connectors

The connector (snap) consists of two connectors: one smaller circular (male) and one larger, typically either hexagonal or octagonal (female). The connectors on the battery are the same as on the connector itself; the smaller one connects to the larger one and vice versa.^[4] The same connector is used on most other battery types in the Power Pack (PP) series. The battery has both terminals on one end. Battery polarization is obvious since mechanical connection is only possible in one configuration.

A problem with this style of connector is that it is very easy to connect two batteries together in a short circuit, which quickly discharges both batteries, generating heat and possibly a fire. The clips on the nine-volt battery can be used to connect several nine-volt batteries in series to create higher voltage.

History

The PP3 appeared when portable transistorized radio receivers became common, and is still called a "transistor" battery by some manufacturers. The Eveready company claims that it introduced this battery type in 1956. ^[5] Early transistorized radios and other equipment needed a low voltage battery, but the lowest voltage commonly available, small battery at that time was a 22.5V battery made for vacuum tube/thermionic valve radios. The 22.5V voltage was at the upper limit of the transistor voltage ratings, and it was clear that what was needed was a battery of lower voltage and high enough capacity to run the transistor radios for a reasonable time.

Technical specifications

These batteries are commonly named 9-volt, and also colloquially named PP3, Radio battery, Square (sic) battery, and Japan "006P".

They all have a rectangular shape; the dimensions are height 48.5 mm, length 26.5 mm, width 17.5 mm. Both terminals are at the small end and their centres are 12.7 mm apart.

Inside an alkaline or carbon-zinc 9-volt battery there are six cells, either cylindrical alkaline or flat carbon-zinc type, connected in series. Some brands use welded tabs internally to attach to the cells, others press foil strips against the ends of the cells.

Rechargeable nickel–cadmium (NiCd) and Nickel-metal hydride (NiMH) batteries have between six and eight 1.2 volt cells. Lithium versions use three 3.2 V cells - there is a rechargeable lithium polymer version. There is also a low self-discharge NiMH version.

Formerly, mercury batteries were made in this size. They had higher capacity than carbon-zinc types, a nominal voltage of 8.4 volts, and very stable voltage output. Once used in photographic and measuring instruments or long-life applications, they are now unavailable due to environmental restrictions.

Type		IEC name1	ANSI/NEDA name2	Typical capacity (mAh)	Nominal voltage
Primary (disposable)	Alkaline	6LR61	1604A	565	9
	Zinc–carbon	6F22	1604D	400
	Lithium		1604LC	1200			9.6
Rechargeable	NiCd	6KR61	11604	120	7.2	8.4 (some)
	NiMH	6HR61	7.2H5	175-300	7.2	some:3
						8.4	9.6
	Lithium-ion polymer			520	9

References:

• ^1 IEC 60086-2011 pt2-§7.6.1.12
• ^2 ANSI C18.1M Part 1 and C18.3M Part 1
• ^3 Does not apply to most batteries of the type

Self discharge

An alkaline battery that is unused or used with extremely low power consumption devices (transistor leak current, etc.) can be expected to last approximately for 6 years, essentially the shelf-life of a new battery.

Lithium 9V/PP3

Lithium 9-volt batteries are consumer-replaceable, high energy density batteries designed to last up to 5 times longer than alkaline 9-volt batteries and up to 10 times longer than carbon-zinc 9-volt batteries in many applications. In addition, lithium PP3 batteries have a long shelf life of up to 10 years. Common applications for lithium 9-volt batteries are smoke / CO (Carbon Monoxide) alarms, and electronic parking meters.

Other nine volt batteries

There are other nine volt batteries, such as PP7 and PP9. These date from the days of early transistor radios and are now less common than PP3. In the days of valve radios which used batteries designed specifically for vacuum tubes, there was a nine volt grid bias battery which had tappings for various voltages between 1.5 and 9.

See also

D, C, AA, AAA, AAAA & 9-volt batteries

• Battery nomenclature
• List of battery sizes

References

1. ^ IEC 60086-2-2011 §7.6.1.12
2. ^ Life Cycle Impacts of Alkaline Batteries with a Focus on End-of-Life - EPBA-EU
3. ^ [1] INOBAT 2008 statistics.
4. ^ IEC 60086-2-2011 §7.6.1.12
5. ^ "Battery History". Energizer.com. http://www.energizer.com/learning-center/Pages/battery-history.aspx. Retrieved 2010-11-27. 

External links

• A Look Inside a 9 Volt Battery
• What charger should I use?
• Your guide to types of household batteries (AAA, AA, C, D, and 9V)
• Brand Neutral Drawing Of 9 Volt Alkaline Battery based on ANSI Specifications
• Brand Neutral Drawing Of 9 Volt Carbon Zinc Battery based on ANSI Specifications
• Brand Neutral Drawing Of 9 Volt Lithium Battery based on ANSI Specifications
• Brand Neutral Drawing Of 9 Volt Rechargeable Battery based on ANSI Specifications