Batteries For Wristwatches, Cameras, And Hearing Aids

Date Posted:15 November 2017 

Have you ever stopped to think about how many appliances we use daily that run on batteries? Not just the standard AA or AAA batteries that power your flashlight or smoke detector (by the way, have you checked it recently?) Do you know what kind of battery powers the phone in your pocket, or the watch on your wrist? When it comes down to it, there are tons of different devices that run on batteries…and different types of batteries that power them. 

The International Electrotechnical Commission (IEC) is a private, world-wide organization that establishes and publishes various standards for all electronic and electric technologies, with a field ranging from electromagnetism, medical technology, and telecommunication. Among these, they also publish standard voltages for all batteries. These include AA, AAA, C, and D batteries, which we’re used to seeing all over. However, they also include rectangular batteries (4.5V, 9V, etc), button cells, and numerous others.
First, we need to learn a few of the basics about batteries. The first thing to know is that all batteries can be either primary or secondary, depending on their ability to be recharged. Every battery relies on a chemical reaction to supply electric power, which takes the form of an electrolyte – a substance that dissolves in a polar solvent (like water) to create an electrically conducting solution -- so by extension, there are chemicals in the battery that make this reaction. 

Primary batteries have chemical reactions that are not reversible, so they cannot be recharged. They’re made to be used until they have no energy left to give. These batteries don’t need to be charged before use; they can be used immediately after purchase. Primary batteries are typically used in devices that have a low current drain or are used sporadically. They’re also used in alarm devices as an independent power source, away from a common generator. 

Secondary batteries, on the other hand, have chemical reactions that are reversible, so they can be recharged. They’re recharged by applying an electric current to the chemicals inside, which reverses their reactions so they can be used again and again. These batteries come in a wide variety, depending on what appliance they power.

A battery consists of one or more cells, which actually house the chemical reaction. There are multiple types of cells, but most common are wet cell and dry cells. A wet cell has a liquid electrolyte, and all internal parts of the battery are covered in liquid, or “flooded.” A dry cell, however, uses as little moisture as possible, and its electrolyte takes the form of a paste. Both types of cells can be found in primary and secondary batteries.

Secondary batteries are more often used in devices like cameras and phones, and come in different forms, depending on the chemicals in them. The first kind invented was the lead-acid battery, which is commonly used in the starters of automobiles and boats. They’re so commonly used because, simply put, they’re cheaper to manufacture and buy than other kinds of batteries. Because they also have a high power-to-weight ratio, they’re also used for stand-alone power systems and large-scale backup systems.

A variation and occasional replacement of the lead-acid battery is the valve regulated lead-acid battery, shortened to the VRLA battery. The electrolyte in a VRLA battery is made of sulfuric acid, which increases the battery’s lifespan and reduced the potential for leakage. There are two types of these: gel batteries, where the electrolyte is in gel form, and absorbed glass mat (AGM) batteries, where glass fibers coated in the electrolyte are woven together into a “mat” to increase the electrolyte’s surface area. 

While a subject such as automobiles might be relatively simple in terms of battery types, the topic of cameras is much more diverse. This is due to most camera manufacturers, who design their cameras to be compatible with a certain type of battery, which they themselves manufacture and sell with the camera. 

Most camera batteries vary based on the chemical used as the electrolyte, which is most commonly alkaline. Alkaline batteries, though they can’t be recharged, have a shelf life of around two years and are widely available in different voltages. 

Other popular types of camera batteries include nickel and lithium, respectively. Nickel-cadmium (NiCd) and nickel-metal hydride (NiMH) are available in various sizes, depending on the camera, and are rechargeable. NiCd batteries are cheaper than NiMH’s, but have a shorter shelf life, and vice versa for NiMH’s. 

Lithium batteries are non-rechargeable, and tend to be the more expensive batteries on the market. However, these also have a longer lifespan than other batteries, so most camera manufacturers have designed their batteries for exclusive compatibility with lithium batteries. A variation on this, the lithium-ion battery, boasts the same features as the standard; however, they’re rechargeable as well. 
However, there are smaller devices, which require smaller batteries. In these cases, various forms of batteries, called “button cells,” are common. Most button cells are named this because they resemble buttons on clothes, only typically a bit smaller. Like other types of batteries, they tend to be mainly alkaline batteries, with nickel and lithium as other common materials. The chemistries of the various batteries means they vary in shelf life and capacity. The electrolyte and voltage of the battery can usually be found on the back of the battery, and they’re manufactured to be either disposable or rechargeable.

Button cells are commonly found in smaller electronic devices, commonly wristwatches. However, they’re also commonly used in the medical profession. Devices such as hearing aids, heart rate monitors, and pacemakers also utilize the size and power-to-weight ratio of button cells.

Batteries are without a doubt the hidden tool that powers almost every technological aspect of our lives. It’s not just the batteries in your remote, either – it’s the battery in your camera, or your watch, or maybe even your pacemaker. For this reason, it’s important to know about them – their different types, voltages, chemical components, and features. It’s also worth taking a look at how often they should be replaced, as well as what batteries will get you the most out of your dollar.


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