Batteries have become an essential part of all electrical and electronics systems. Whether it is a remote-controlled car or a solar panel system, everything now has a battery connected to it. In this article, we’ve addressed the most common questions about batteries, their operation, and their integration in electrical units.
What is a battery?
A battery is an electrochemical source for generating energy to power appliances like mobile phones, electric cars, electric toothbrushes, etc. Invented in the 1800s, batteries consist of two electrodes and an electrolyte. When a battery is connected to an external circuit, the circuit is complete and the electrolyte inside the battery undergoes a redox reaction. This redox reaction generates electricity that is used to power the functions of the external circuit.
The history of batteries
The term “battery” was coined by Benjamin Franklin in 1749, who used it to describe a series of capacitors he had linked for an experiment. In the later years, the term battery was used for any electrochemical cells that were linked together with one specific purpose: to generate power.
The modern battery has three basic components: one (+) electrode, one (−) electrode and an electrolyte. The design of this type of battery was first developed in 1780 by Alessandro Volta and Luigi Galvani when they were dissecting a frog using a brine solution. The batteries that followed this work were mainly non-rechargeable for several decades. The first rechargeable battery was not invented until 1859. These were sulphuric acid-based batteries, that are now considered harmful to the environment.
Since 1749, when the term was first coined, to now, 2021, battery technology has undergone extensive technological development. While batteries invented in the 1750s were nothing more than small circuits used for experimentation, batteries have found their use in almost all appliances and devices. Many contribute to the popularity of electricity and the resulting boost in the economy to the invention of the battery.
However, despite technological development, the number of components used in a battery have remained the same. We still use only three components to make a battery—the same three components mentioned above. The major technological development that is noticed is the material used to make these components.
The original batteries created by Alessandro Volta were made out of copper and zinc metals and used brine i.e., saltwater as an electrolyte. As these components have been explored, these three have been replaced. Now, lead-acid batteries – which are among the most popular batteries in the world – use a lead and sulphuric acid to generate power.
Another notable difference is that the original batteries were not portable. These were large, bulky batteries, very similar in size to the batteries we now see in cars. However, because these batteries were inefficient, they did not meet high power requirements. Instead, a battery of this large size was used for the same applications. Modern batteries are lightweight and portable – as demonstrated by the AA batteries we use in remote controls and flashlights. Rechargeable and non-rechargeable batteries now come in all sizes.
The future of batteries
Rechargeable batteries are considered the future of battery technology. These batteries are not use-and-throw batteries and, as a result, do not cause major pollution. Today, rechargeable batteries are used in various appliances like mobile phones and laptops; however, they are yet to make their debut in mainstream applications like remote controls. While rechargeable battery options are available for this purpose, they are largely not used by people because of lack of knowledge.
Batteries are often considered the cornerstone of development in science and technology. Before the development of batteries, most scientists were able to use electricity to conduct experiments. However, these experiments were limited by the lack of storage options. Scientists could not complete experiments in the field unless they had access to electricity. This was a major disadvantage because not all parts of the world had an electricity grid.
This changed once the battery was invented. Because these batteries could store electricity, experiments could be completed at the scientist’s convenience. The batteries, however large, could be carried out to complete experiments. These two advantages of batteries helped science and technology develop faster.
Today, batteries are an essential part of our lives. From the mobile phone, we use to watch the news to the Bluetooth headset we use to listen to music, there is no appliance that does not have an integrated battery. This makes understanding how a battery works and how it is created all the more important. In the sections following this, we have addressed how a battery works and how you can build a battery on your own – two questions that will help you understand more about the technology that influences a majority of our lives.
Opening a battery
As aforementioned, the battery contains three main components:
- The positive plate (the anode)
- The negative plate (the cathode)
- The acid (electrolyte)
The three components are placed inside a box of approximately 5 kgs. The components are closed inside the box using a cover. The covers are secured using multiple caps and have two short or long handles. The box and the cover are both made from plastic.
On the cover, the manufacturer denotes the positive terminal with a large (+) symbol and the negative terminal with a large (-) symbol.
How does a battery work?
A battery works on a simple idea: it converts chemical energy directly to electrical energy. A battery contains two plates - a positive plate and a negative plate. When they are connected in an external circuit, for example: when a battery is placed in remote control, the circuit is complete and the electrodes are connected. This connection encourages redox reactions and the generation of electricity.
The energy generated is equal to the bond energies of the metal, oxides, or other molecules undergoing the reaction. The energy released is measured in ‘volts’; therefore, most batteries are rated according to the voltage they provide rather than just the name of the battery. To understand the rating of a battery, it is first important to understand how a battery works.
The make-up of a battery
The principle working of a battery is dependent on the flow of electrons. Therefore, for any battery to work, it needs one material that will give out excess electrons, and one that will accept excess electrons. These materials are called electrodes. The material that gives electrons is called the positive plate, and the one that accepts electrons is called the negative plate. The positive plate and the negative plate are generally two different types of metals. In Volta’s cell, zinc was used as the positive plate and silver as the negative plate.
The positive plate and negative plate are designed as a “sandwich” and in between the two is the electrolyte. In older batteries, the electrolyte was exclusively a liquid (like brine); however, modern batteries feature electrolytes in gel and solid forms. Together, the electrolyte, positive plate and negative plate make up one cell.
A battery can have one cell or a combination of many – depending entirely on the manufacturer’s design. A 12V battery in series connection contains 6 cells; each cell is 2V power. Each cell is separated by insulators to ensure the cells do not touch each other or the plastic box. The insulators are simple rubber casings that contains metal plates and a membrane. The membrane allows the passage of charge.
Most modern cells have two plates – one of copper and one of lead. Each cell has its own positive and negative terminal. In a series connection, the cells are stacked and the positive of one cell is connected to the negative of the other cell. Therefore, one end of the battery has a positive terminal while the other end has a negative terminal.
The electrolyte or acid is filled in the AGM separator which releases the electrons.
The working of a battery
The working of a battery sounds technical but can be broken down into several smaller steps:
- At the positive plate, the metal reacts with the electrolyte. This reaction releases free electrons.
- When the battery is placed inside an appliance – for example, a remote – the electrons will move through the circuit in the remote and to the opposite end of the battery.
- Here, the negative plate will accept the electrons, completing the process.
There are two key things to remember when understanding the working of a battery:
- This reaction cannot happen if there is no external circuit. Therefore, when a battery is not connected to a circuit, it does not discharge because the reaction does not take place.
- All electrons given out by the positive plate need to be accepted by the negative plate. This completes the reaction.
This is the basic working of a battery that has been researched to create modern batteries. Unlike Volta’s batteries, modern batteries use a combination of other metals and alloys. These combinations dictate the power of the battery. The number of electrons in the circuit at a given point is used to determine the power of the battery.
For larger batteries, the number of cells increases, and the rating of each cell also increases. All batteries have the same components, and therefore, the only way to make larger batteries is to increase the number of cells or to increase the rating of each battery.
Electrodes in rechargeable battery
In non-rechargeable batteries, the electron transfer from the positive plate to the negative plate depletes the positive plate. Therefore, after multiple uses, the positive plate becomes thinner while the negative plate becomes fatter. When the positive plate no longer has any electrons to give, the battery stops working.
The working of a rechargeable battery is the same. However, in this type of battery, you can charge the battery. In this process, an opposite potential is applied. When this is done, the electrons move from the negative plate to the positive plate, reversing the reaction. When all the electrons have reverted to the positive plate, the battery is 100% charged. It can be removed from the charging port and can be used again.
This simple principle of battery working allows anyone to make a battery at home. While sophisticated designs cannot be tried, simple designs can be made.
How battery is manufactured?
The science behind battery manufacturing is not very complicated, and because batteries are a widely explored technology, batteries can also be made at home. The simplest method to make a battery is as follows:
- Gather the electrodes: To build the most effective battery, two types of electrodes are required. One electrode undergoes oxidation while the other undergoes reduction. For homemade batteries, use a pure aluminum strip and a pure copper strip.
- Create an electrolyte: An electrolyte is any liquid or slurry that will facilitate the reactions at each terminal. For homemade batteries, use a mixture of liquids including saltwater, vinegar, and bleach.
- Creating the junction: Select plastic or insulating material to hold the electrolyte. The mixture can also be poured into a plastic bowl or cup. Place the electrodes on opposite ends of the bowl and dip one end into the mixture.
- Checking the system: At the end of each electrode, connect a wire using an alligator clip. Test the voltage by connecting to a voltmeter or low voltage appliance.
This same method is used to create high-powered batteries. Most battery manufacturers adjust the quantity and type of molecules and electrodes inside the battery to adjust the electrical voltage they provide.
The method given above is the simplest and most basic method of building a battery. Commercially available batteries use different processing methods to give different results. The simple design above is combined with commercial technology to create 100% safe batteries we can use in our everyday life.
First, commercially available batteries do not have liquid electrolytes in a bowl-type holder. The batteries available in the market now use an absorbent glass mat (AGM) separator as an adsorbent to hold the electrolyte.
Second, the plates used in a battery are usually lead and carbon. These two plates provide the best electron transfer and therefore, they facilitate the best charge transfer. These plates have a standard dimension and weight.
Finally, these items are placed in a rubber casing. The rubber casing also contains a membrane. They do not conduct electricity, but they do allow charges to pass. Therefore, when the battery is turned on, the charges pass, and electricity follows. This is called one cell. In a commercial battery, several cells are stacked to one battery.
Making a commercial battery
All batteries have the same items; however, what differentiates one battery from another is the process used to make the battery. Each battery manufacturer has the same items to start, but they use different and proprietary processes to manufacture the battery used in homes. Some key steps in the manufacturing process are explained in detail.
Preparation. The process starts with the preparation of each item. Most manufacturers have their unique formula for an electrolyte which includes a binder, active agent, and conductive agent. Thus, the electrolyte is prepared. In addition, the electrode plates are cut until they have the desired weight.
Coating and drying. The AGM separator is coated with the electrolyte. It is dipped in the solution or slurry until the AGM separator absorbs the desired amount. Once the absorption is done, the separator is dried.
Calendaring. The electrode plates are compressed together until they stick to one another. For this process, extreme force is used to ensure the plates do not separate. They are driven between two large cylinders to decrease the thickness of the electrode plates.
Cutting. Once the electrode plates are stuck together and are of the desired size, they are cut together. Machines like CNC are used to cut the plates into required shapes. Most plates are cut into squares or rectangles. Many manufacturers also have unique molds or shapes that they use to cut the plates into the desired shape. Most cells are of 2V.
Battery assembly. Once the cutting process is completed, the assembly of the cell can be done. In most cases, the cells are stacked, with alternating layers of electrode plates and AGM separators. The stack is placed in a plastic box and the electrolyte is injected to connect each cell and terminal.
As aforementioned, the number of cells and the number of electrolytes depend on the size of the battery. For a standard-size battery, 6 cells of 2V are stacked. However, for larger batteries, more cells can be included.
This is the standard manufacturing process. While the size, shape, manufacturer, and even the type of battery may change, these key steps remain the same. However, for a user, this does not make a significant difference; instead, what matters is the type of battery used.
What are the applications of the battery?
The battery is used in various applications such as home, torch, wall clock, railway, automobile vehicles, etc.
Types of batteries:
Batteries are segregated into two broad types:
- Primary batteries: Primary batteries are commonly known as use and throw batteries. These can be used in any appliance and once the charge is used, they have to be disposed of. For example, AA batteries are used in remote controls.
- Secondary batteries: Secondary batteries are also known as rechargeable batteries. These batteries can be used multiple times without any damage to the appliance or the battery. For example, batteries in laptops, mobile phones, or any other rechargeable electronic appliance.
Primary batteries are not used for larger appliances. Instead, they are sold as individual AA batteries. Secondary batteries have become more popular in the past few decades. Owing to their rechargeable nature, they reduce environmental footprint and cause less pollution. These batteries are often used in all appliances including solar systems and inverters.
In the current market, there are three types of batteries that are recommended for residential applications:
1. Lead-acid Battery.
The lead-acid battery is the oldest type of battery, invented in 1859. They are the most inexpensive batteries available in the market. They are very powerful, rechargeable, and easily available, making them the most popular battery in India. They are also easy to manufacture and install in any home.
However, these batteries have low power density. This makes the lead-acid batteries very heavy and very large. In addition, lead-acid batteries are not environmentally friendly since they cannot be degraded. They cannot withstand water and so, are damaged as a result of rain.
2. Sealed Maintenance Free (SMF) Battery.
Sealed Maintenance Free batteries are a type of lead-acid battery. However, while lead-acid batteries require regular maintenance, these do not. In a traditional lead-acid battery, electrolyte (acid) needs to be topped up at regular intervals to make sure the battery works properly. In an SMF battery, there is no need to top up.
This has another advantage: SMF batteries can be transported. These batteries are 100% sealed, and the acid inside will not leak, making them safe for transportation. The sealing also helps in reducing the emission of gases or fumes.
3. Lithium battery or Lithium-ion Battery.
The lithium battery is the up-and-coming starter. They have high density, low self-discharge rate and are extremely lightweight. One major advantage of this battery is that they have the lowest maintenance requirements among all battery types.
These advantages of lithium-ion batteries are the reason why they are now replacing lead-acid and SMF batteries in automobile and residential applications. Solar panel systems, electric vehicles and many appliances now use lithium-ion batteries.
How to select a battery for a home?
Batteries have a lifespan of 3–5 years, making them a long-term investment for most homeowners. If the home has an inverter, a battery can be selected based on the Ah range recommended by the battery. There are four things to consider when buying a battery:
- The capacity of the battery: The capacity of a battery explains how much energy is stored in the battery. For average residential homes, a 150 Ah capacity battery is needed. However, batteries with 80–220 Ah capacity are also available.
- Warranty of the battery: Warranties for batteries range from 2 years to 5 years. This depends on the type of battery (flat plate, tubular, or lithium) and the manufacturer.
- Backup power of the battery: Battery power backup depicts how many hours the battery could support a battery after a power cut. For example, a 150 Ah battery can provide 200 watts for 7 hours, 300 watts for 5 hours, or 400 watts for 3.5 hours.
- The lifespan of the battery: The lifespan of a battery depends upon the type of battery. Lead-acid batteries can be charged 500–1200 times, while the lithium battery can be charged 1000-2000 times.
When reviewing options for the best battery, these pointers can be used to narrow down the choices.
How long does it take to charge a battery?
It depends on the size of the battery but usually, the battery starts working with 10-15% charging. Usually, it takes 3 to 4 hours for a home battery whereas automobile battery charges in lesser time. Now efficient mobile battery charger available so it charges battery very fast in less than an hour.
Calculating the backup time by Ah
Power backup totally depends on the size of the battery (Ah x Volt), It means the more ah battery will give more backup in long run.
How to calculate battery capacity for the inverter?
It can be easily observed from Ah, i.e., Ampere-Hour.
Battery and capacitor are different kinds, a battery stores electrical energy as chemical energy while a capacitor stores electrical energy.
Most Indian households have inverters and battery systems. The size of the battery can be calculated by the formula:
Battery capacity: (Total load x Backup time) / Input voltage
The battery capacity calculated using this formula will be in hours.
How long will a battery last?
How to calculate inverter battery backup time?
The formula can also be adjusted to calculate battery backup time:
Battery backup time = (Battery capacity x Input voltage) / Total load
The battery backup time calculated using this formula will be in hours.
These formulas can be used to select the battery for any home. However, this also depends on the number of watts of load needed to run home after a power cut. Most homes with all common appliances like refrigerators, fans, laptops, etc. need 200–300 watts to run.
Therefore, if a battery of 150 amps (12 V) is bought, the calculation for the battery is as follows:
Voltage: 12 V
Watt storage capacity of the battery = Ampere x Voltage = 150 x 12 = 1800 watt
Most batteries are only 80–90% efficient. Therefore, you will be able to use only 80–90% of 1800 watts = 1400 to 1500 watts.
Therefore, the battery capacity is 1400–1500 watts.
The backup time of your battery depends upon your usage:
200 watts – 7 hours
300 watts – 5 hours
400 watts – 3–4 hours
Batteries are a long-term investment. There are only two problems that can permanently destroy a battery:
- Overcharging: When the controller in the inverter is broken, the battery may undercharge or overcharge. If the battery overcharges, the cells inside heat up and the plate’s oxide melt. Once the cell is damaged, it cannot be fixed.
- Dry cell charging: Each manufacturer has an electrolyte or water level indicator in the battery. If the level is not maintained, the cells dry out. If the battery continues to charge, the cell is damaged. This problem is common in lead-acid batteries.
What to do with scrap battery?
An old battery can be recycled so we can sell it to the manufacturer at a discounted price, or it can also be replaced with a new battery.
If you are looking to install a solar panel system and wish to connect the system to an inverter and battery, you should also consult an expert. A solar expert will be able to help you find the right battery for your system. Since there are many options available, we recommend conducting thorough research before investing in a battery.