“Household batteries” are the small portable batteries used daily by most people in devices such as radios, toys, flashlights and lanterns, games, watches, calculators, cameras, telephones and other communications devices, but do not include the larger batteries motor vehicles, commercial and industrial and other applications. They are called “dry cell batteries” because they contain no freestanding bodies or pools of liquid electrolyte. Household batteries are divided into two large categories, primary (meaning not chargeable) and rechargeable (also called secondary) batteries.
“Household batteries” are the small portable batteries used daily by most people in devices such as radios, toys, flashlights and lanterns, games, watches, calculators, hearing aids, cameras, telephones and other communications do not include the larger batteries used in motor vehicles, commercial and industrial, military and other applications. They are called “dry cell batteries” because they contain no freestanding bodies or pools of liquid electrolyte. Household batteries are divided into two large categories, (meaning not rechargeable) and rechargeable (also called secondary) batteries.
Basic factual information about household batteries includes:
- The names commonly used to describe them;
- Whether they are primary or rechargeable;
- Their voltage per cell;
- Their “chemistry,” meaning the specific combinations of reactive constituents they contain;
- Whether they are hazardous under federal law;
- The geometric sizes and shapes in which the batteries are produced; and
- Frequent applications of the batteries.
Nickel Cadmium Batteries
Nickel cadmium rechargeable batteries are produced in D, C, AA, and AAA cylindrical sizes, and in the 9-volt rectangular size (Figure 11), and in some applications can be used as alternatives to alkaline batteries. In addition, individual batteries are assembled into packs of whatever size and shape is needed for a particular device. Nickel cadmium battery packs are used in portable power tools and appliances, cordless telephones, personal care products, and other devices.
Compared with alkaline batteries, nickel cadmium batteries have only about one-third the energy density, but can discharge at higher rates. They also have a high internal self-discharge rate, making them a poor choice in certain applications such as smoke detectors and emergency flashlights. They are used in applications requiring high power and where frequent charging is possible, but not in applications where long periods of unattended storage will occur.
Nickel-Metal Hydride Batteries
Like nickel cadmium batteries, nickel-metal hydride rechargeable batteries are produced in D, C, AA, and AAA cylindrical sizes, and in the 9-volt rectangular size, and are used in some applications as an alternative to alkaline batteries . They are also assembled into packs of various sizes and shapes.
Nickel-metal hydride battery packs are used in cellular phones, laptop computers, video cameras, power tools, and other devices requiring high power and premium performance. Nickel-metal hydride batteries are similar to nickel cadmium batteries, except that metallic rare earth alloys are substituted for cadmium in the negative electrode.
Lithium Ion Batteries
Lithium ion rechargeable batteries are produced in a variety of cylindrical and rectangular sizes. Many are designed with dimensions to fit into the battery compartments of specific small portable devices, such as cell phones, laptop computers, video cameras, and other portable equipment.
Lithium ion batteries are not interchangeable with batteries of any other chemistry, even where the sizes and shapes would otherwise make them interchangeable. The voltage is different from any other battery and the charging requirements are different from other rechargeable batteries.
Small Sealed Lead Acid Batteries
Small sealed lead acid batteries are manufactured in cylindrical and rectangular shapes. In consumer applications, these batteries are used in older video cameras.
Primary lithium batteries are produced in different shapes and sizes. Lithium coin cells, given that name because of their similarity in appearance to coins, are used in keyless remotes, personal digital assistants, watches, hand-held games, and other devices. These coin cells cannot be interchanged with button batteries of different chemistries because of different sizes and different voltages. Cylindrical lithium batteries, which come in 1.5-volt and 3.0-volt varieties, are produced in various sizes and are primarily used in photographic, high-drain, andother applications. The 1.5-volt variety is interchangeable with standard “AA” batteries, whereas the 3.0-volt batteries are different shapes and sizes and are not interchangeable with AA and AAA sizes. Rectangular 9-volt lithium batteries are used in fire and smoke detectors and in medical devices.
Lithium primary battery voltages remain essentially constant until all of the metallic lithium has reacted and the battery is fully discharged. In other words, there is no reactive lithium metal remaining in the batteries when they are replaced and disposed.
By far the most commonly used household batteries are alkaline, also referred to as alkaline manganese batteries. Cylindrical alkaline batteries are mainly produced in D, C, AA, AAA, AAAA, and N sizes, while rectangular (prismatic) alkaline are mostly produced in sizes to fit in 9-volt and lantern applications.
Alkaline batteries are also produced in sizes and shapes known as “button cells”, which are given that name because of their similarity in appearance to buttons. Alkaline button cells are also combined in stacks to produce cylindrical batteries with higher voltages. Alkaline batteries are used in radios, toys, flashlights, lanterns, games, watches, calculators, cameras, fire and smoke detectors, tape and compact disc players, portable stereos, telephones and other communications devices, and other products.
Alkaline batteries have high energy density (energy per unit of volume), high rate capability (ability to discharge rapidly), very long shelf life, and good performance over a wide range of temperatures. At one time, small amounts of mercury were used as an additive in alkaline batteries to suppress formation of internal gasses which otherwise would lead to leakage, possible ruptures, and/or short shelf life. In response to environmental concerns, battery manufacturers developed new technologies that eliminated the need for mercury, except in button cells. Cylindrical and rectangular alkaline batteries have been produced in the United States, Europe, and Japan without the addition of mercury since at least 1993. The addition of mercury to these products was made illegal in the U.S. under 1996 federal battery legislation.
Zinc Carbon Batteries
Known generically as zinc carbon or carbon zinc batteries, and sometimes bearing words such as “Heavy Duty” or “General Purpose” on their labels, these products were in widespread use before the development of alkaline batteries. Although still sold and used, zinc carbon batteries have largely been surpassed in the United States by the alkaline products. In general, they are manufactured in the same shapes and sizes, and are used in many of the same applications as alkaline batteries, except that there are no zinc carbon button cells. As with alkaline batteries, small quantities of mercury were formerly used in zinc carbon batteries to suppress gassing. As a result of new technology, this practice had ended in the United States by 1992. The addition of mercury to zinc carbon batteries was prohibited by 1996 federal battery legislation.
Zinc Air Batteries
Zinc air button cell batteries are the dominant power source for hearing aids. Stacks of zinc air button cells are combined into a rectangular format to produce batteries used in medical devices. Oxygen, which reacts with the zinc electrode, is obtained from air that enters the battery through one or more small holes in the battery casing. Because of the need for a continuous supply of air, zinc air batteries cannot be used in watches and other tightly sealed products. A sealing tape is kept across the hole(s) to prevent entry of the air until the battery is to be activated. The battery will discharge continuously after the sealing tape is removed, meaning that it can be used most efficiently in devices which are used continuously or for high percentages of the day (such as hearing aids).
Small amounts of mercury are used in zinc air button cells.
Silver Oxide Batteries
Silver oxide (also known simply as silver) button cell batteries are used in watches, calculators, hearing aids, and cameras. Small amounts of mercury are used in silver oxide button cells.
Mercuric Oxide Batteries
A primary battery chemistry known as mercuric oxide, or simply as mercury, uses mercuric oxide and zinc electrodes and an alkaline electrolyte. Because the mercury in these batteries is used as an electrode rather than as an additive, it cannot be eliminated and it is inherently present in high concentrations, usually 35–40 percent of the total weight of the batteries. Mercuric oxide button cells, which were once widely used in hearing aids and watches, are now prohibited under the 1996 federal battery legislation. Larger sizes of mercuric oxide batteries, produced in rectangular and cylindrical shapes, have been replaced in many applications by alkaline and zinc air counterparts.
Which Battery Should I Select?
With so many different batteries available, which one should I select for my application? The question can be answered by comparing the characteristics of each battery type with the requirements of the application.
- First, select a battery having the needed size, shape, and voltage.
- Second, consider the drain or power requirements of the application. Low drain applications include radios, clocks, and flashlights. Moderate drain applications, which include the majority of today’s electronic products, include tape recorders, Game Boys, music and CD players, electronic toys, pagers, boom boxes, smoke detectors, remote controls, and flashlights that get lots of use. Products with high drain requirements include digital cameras, palmtops, remote- control toys, portable televisions, and photo flash units.
- Third, consider the shelf life or storage requirements. If a battery-containing device can be easily recharged frequently, then a rechargeable battery may be a possible power source for the application. On the other hand, if the battery must be able to retain its power for long periods of inactivity, then a battery having a long shelf life should be selected.
- Fourth, consider costs. For some applications, there are reasonable alternatives available and, in those cases, costs become a consideration.
Following this decision-making process will result in the selection of the best battery for a particular application and budget. It does not, however, address the environmental issues about battery disposal and recycling. The latter involves questions about whether the used batteries are hazardous, and whether a recycling option is available. The choice of which battery to purchase should not be made mainly on the basis of battery disposal and recycling criteria, because it has a high chance of leading to the selection of a battery which does not meet an application’s performance requirements. The selection of the wrong battery for a particular application represents a bad decision, regardless of what disposal and recycling options are available.