When you mention the terms 'button cell batteries,' you might confuse some people with what you mean. But when you talk of a watch battery, everyone will be on the same page with you. Therefore button cell battery or watch battery is a small-sized single cell battery with a squat cylindrical shape of about 5 to 25 mm in diameter and a height of about 1 to 6mm. These characteristics make it earn the name 'button.'
The button cells are used in portable gadgets like wrist watches and pocket calculators. The positive terminal is made of a metal can, while the negative terminal has an insulated cap. Button cell batteries are designed to run these devices for an extended period. The wrist watches and pocket calculators also consume a small amount of power. The button cell batteries can be used for over one year.
Most button cells are designed to have a low self-discharge, and they can hold a charge for an extended period even when not in use. The button cells are single and disposable primary cells. Their anodes are either made of lithium or zinc, while the cathodes are made of manganese II oxide, silver oxide, cupric acid, carbon monofluoride, or oxygen gas.
Are button cell batteries the same?
The button cell batteries differ according to their chemical composition, voltage capacity, ability to charge, and sizes.
In this category, alkaline batteries have the same sizes as others but offer less capacity and less constant voltage than the costly silver oxide and lithium cells. Silver cells have a stable voltage that they give out until it finally drops at the end of life. Mercury cells offer substantial voltage, but it is prohibited in most countries due to its toxicity and environmental impact.
Another type is zinc-air batteries that make fair use of the air as the depolarizer and have a higher capacity than the other button cell types. They take their air from the environment, which makes them more stable. These zinc-air batteries have an air-tight seal that must be broken and removed before use. They dry out in a few weeks without taking into consideration the use time.
The button batteries have a two-digit code representing a standard case size or a 3- or 4- digit code that gives the diameter and height. The first two digits show the cell's outer diameter in millimeters, rounded down; the standard gives exact numbers, and there is no ambiguity.
For example, CR2032: lithium is 20mm in diameter and 3.2mm high.
SR516: silver is 5.8mm in diameter and 1.6 mm high.
Most button cells cannot be recharged, but there are a few which can be recharged. The rechargeable batteries have a lower capacity than the ones for single use. The single-use button cell batteries are made to fit into the holder or with solder tags for permanent connectivity. The use of a rechargeable button battery is to back up the settings of the mains-powered equipment.
Rechargeable batteries possess the same dimension based numeric code but different letters. CR2032 is a single-use battery while ML2032, VL2032, and LIR2032 are rechargeable button cells that fit in the same holder as their counterparts.
Different types of button cell batteries have different capacities. The nominal voltages of batteries with different chemical properties are as follows:
- Alkaline – 1.5 volts
- Silver – 1.55 volts
- Zinc-air – 1.4 volts
- Lithium – 3.0 volts
- Nickel oxyhydroxide – 1.5 volts
Are button cell batteries dangerous?
Button cell batteries appear to be harmless, but they can be so dangerous. If swallowed, the button cells pass straight through to the stomach and out through the other end. If a child or a person swallows the battery and gets stuck at any point, it will continue the emitting charge, leading to burns on the tissues affected. It can lead to long term injuries and fatal ones.
Lithium coin batteries are the most dangerous. They can burn through the organs and blood vessels within a short time. Most parents usually realize that the child has swallowed something when they start vomiting. But for lithium coin cells, this will be too late because the damage would have already occurred.
There are several things you should avoid or do when using button cell batteries. This include:
- Never reverse the positive and negative terminals. A gadget that uses three or more batteries can work even when one is not inserted in the right way. If the battery reversed starts recharging, it might explode, leak, or gain heat.
- Do not short circuit button cells. When carrying or storing button cell batteries, do not mix with metallic objects. This is because metallic objects can connect the batteries leading to a massive flow of electrical currents. Hence, this can lead to heat generation, explosion, or fire. Button cell batteries are metallic; thus, you should ensure they are insulated when storing or carrying them.
- Do not recharge the button cells that are not rechargeable. Recharging coin cells that are not rechargeable can lead to fatal accidents.
- Do not mix old and new or different battery brands in one gadget. Use the same brands of batteries in the same device. Also, do not mix old and new because it can result in explosion, leakage, heat generation, or fire.
- When batteries run down, remove them in the soonest time possible.
- Please do not throw the button cell batteries into the fire because they can explode and cause fatal accidents.
- Never apply solder directly to the button cell battery's terminals. The heat from the solder will melt the insulator hence creating internal short-circuiting.
- Never modify or disassemble button cell batteries or nay battery type. The chemical contents of the battery can be dangerous and may cause chemical burns.
- Always keep the button cell batteries out of reach of children. Button cell batteries are dangerous if swallowed or inserted into the nose or ear. They can cause damage to the tissues. Therefore in case one swallows a button cell battery, seek medical advice immediately.
- Turn off battery-powered devices when you are not using them. Many causes of battery leakages are caused by leaving the devices on even when not in use.
- Do not store the batteries in places subject to high humidity or exposed to direct sunlight.
- It would be best if you never wet the button cell batteries.
Never remove the battery label. Removing the labels makes the battery susceptible to short-circuiting, leading to overheating, leakage, or explosion.
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