What Is A Battery: Cells That Produce A Direct Electric Current (DC).

Do you want to know about batteries? Then, read through this article on what is a battery and be informed.

All the information you require on the battery is here.

For the purpose of clarity, I will start with an overview. This will be followed by how it works. After which you will get its different classifications and types.

Subsequently, you will see how to define its capacity and the various sizes along with their voltages. Next will be the connection of cells in a DC circuit.

The next section will discuss solar batteries. After which you will get a recommendation of the 5 best solar batteries available.

Finally, I will provide answers to some frequently asked questions on batteries.

What Is A Battery: Overview

What Is A Battery_ Overview

Electricity is the continuous flow of charges through a conductor. To get electric current flowing through a conductor, there should be a potential difference across the conductor.

However, the current flowing through a conductor could be alternating or direct current. What distinguishes the type of current is the source.

For alternating currents, you will have the generator or alternator. On the other hand, a cell produces a direct current.

Therefore, a battery is a device that can transform chemical energy into electrical energy. It is a source of electrical power that consists of one or more electrochemical cells. These cells produce a direct current.

Furthermore, a battery is the earliest form of electrical energy. It is a result of an experiment conducted by Alessandro Volta.

In 1800, Alessandro Volta experimented with a stack of copper and zinc plates. These two plates were separated with a brine-soaked paper disk. As a result, it produced a steady current for a considerable duration.

Also, Volta thought he had created an inexhaustible energy source. Hence, he saw the effects of corrosion on the electrodes as a mere nuisance.

However, Michael Faraday proved him wrong with his experiment in 1834. Contrary to Volta, the corrosion effect was not a mere nuisance. Rather, it is an unavoidable consequence of their operation.

The early batteries were of great value for experiments. Nevertheless, their voltages fluctuated and they could not produce a large current for a long period.

With time, there was advancement in the production of cells, ranging from the Daniell cell to the invention of dry cells. The dry cell uses paste as its electrolyte.

Thus, the dry cell took over from the wet cells that used liquid electrolytes. These liquid electrolytes were prone to leakage if not properly handled.

What Is A Baterry: How It Works

A battery stores chemical energy and converts it to electrical energy. This is referred to as electrochemistry. Thus, it is a pile of electrochemical cells.

Furthermore, an electrochemical cell consists of the anode, cathode, and electrolyte. The anode and cathode are called electrodes, with a negative cathode and positive anode.

The anode reacts with the electrolyte to produce electrons around the anode. Also, the cathode reacts with the electrolyte to enable the cathode to accept electrons.

These chemical reactions are reduction-oxidation reactions (redox reactions). The oxidation occurs at the anode while the reduction occurs at the cathode.

More so, the unstable build-up of electrons at the anode creates an electrical difference between the anode and the cathode. The electrons tend to arrange themselves to get rid of this difference.

Nevertheless, the electrons repel themselves and tend to move towards the cathode. Hence, the semi-permeable barrier in the electrolyte obstructs this.

Therefore, when the battery is connected to a closed circuit, the electrons flow to the cathode through the conductor. Hence, the electric current is the result of this movement.

Consequently, this electrochemical process changes the chemicals in the anode and cathode. Thus, it stops supplying electrons. Therefore, the amount of energy in a battery is limited.

In the case of rechargeable cells, the direction of the flow of electrons changes. As a result, the electrochemical process happens in reverse.

Hence, the cathode and anode are restored to their original state. This makes this cell able to supply full power again.

What Is A Battery: Classification Of Cells

The electrochemical cells are broadly classified into primary and secondary cells.

Primary Cells

A primary cell is a cell that you can not easily recharge after a single use. Thus, you discard it after using it once. Hence, its electrochemical process is irreversible.

However, few primary cells are galvanic. That is, they generate energy from a spontaneous redox reaction.

Thus, most of the primary cells are dry cells – that uses electrolyte in an absorbent material.

The Primary cells could either be a simple cell, leclanche cell, or daniel cell.

Primary Cells Batteries Benefits

  • They have a lower initial cost.
  • Also, they are lighter and smaller. Hence, they are more suitable for portable devices.
  • More so, they have good charge retention.
  • You can readily replace them.
  • Lastly, they do not require periodic maintenance.

The Primary Cell Batteries: Drawbacks

  • They are useful only once.
  • Also, they are limited to specific applications.
  • It is not rechargeable.
  • They are not useful in heavy systems.

Types Of Primary Cells In Practical Application

This shows the different types of primary cells and their chemical construction.

Lithium Batteries

Lithium batteries offer a very high energy density. Thus, they can store enough energy compared to other cells.

You can only find them in AA, AAA, and 9V sizes. Even so, they have the highest mAh rating among other primary cells (non-rechargeable cells).

They have a rating that ranges from 2700 to 3400 mAh. Thus, they can last a long time.


  • They are suitable for portable devices.
  • Also, they are ideal for heavy use.
  • Even so, extreme temperatures do not affect them.
  • More so, they are good for emergency devices.
  • They last longer than other non-rechargeable cells.
  • Lastly, their shelf life is about 10-12 years.


  • They are more expensive than other non-rechargeable cells.
  • Also, they are inflammable.

Silver Oxide Batteries

These are used mostly in wristwatches and some other small devices. It is often sold in button cells. This makes the value of silver insignificant to the overall cost.


  • Its energy-to-weight ratio is high.
  • Also, its operating life is exceptionally long.
  • Even so, it is suitable for flat devices.
  • Lastly, it has a high energy capacity.


It is expensive.

Carbon Zinc Batteries

These cells are cheap. They have a low energy density. More so, they often supply less power.


  • They are cheap and easy to find.
  • Also, they come in different shapes and sizes.


  • They can not perform well in extreme temperatures.
  • Also, they have a shelf life of 2-3 years.
  • Even so, their energy level is low.

Zinc-Air Batteries

This set of cells produces power when they are exposed to air (oxygen). They are ideal for hearing aids.

To activate the battery, you just need to remove a sealing tab. Thus, enabling airflow.


  • They are not expensive.
  • Also, they have a high energy density.


  • They do not last long.
  • Even so, they are sensitive to extreme temperatures.

Alkaline Batteries

The alkaline cells often have a capacity of 2500mAh. They are easy to dispose of. Also, they are very popular and economical.

Most standard-size batteries use alkaline. Thus, they are suitable for most devices. They are free from lead, mercury, and cadmium.


  • They are of good quality.
  • Also, they last long.
  • Even so, they have a shelf life of 5-10 years.
  • More so, they operate in extreme temperatures.
  • Lastly, they can be easily disposed of.


  • They might not work well in drain devices.
  • Also, they go unstable sometimes due to leakage.

Secondary Cells

The secondary cells are rechargeable after use. However, this is done by passing the current through its terminals in an opposite direction to the current while discharging.

You can utilize this cell as energy storage that delivers power on demand. Thus, you need to connect it to a primary power source.

Also, you can use it as a primary power source. In this case, you charge the battery after use.

Secondary Cell Batteries: Benefits

  • They are rechargeable.
  • Also, they are suitable for heavy load systems.
  • Even so, they are useful in load-leveling, emergency backup, etc.
  • They are durable.
  • Lastly, they have lower life-cycle costs.

Secondary Cell Batteries: Drawbacks

  • They require regular maintenance.
  • Also, you need to charge them from time to time.
  • Even so, it is not easy to find replacements.

Types of Secondary Cell Batteries

Below are some of the secondary cells in practical use.

Lithium-Ion Batteries

The lithium-ion batteries are very popular. They are the most regularly used in our today’s world. Generally, they are known as Li-ion batteries.

Also, they are rechargeable cells that can be used over and over again. They require no maintenance. Even so, they provide high energy density.

However, these Li-ion cells could be dangerous if you place them in a regular battery-recharging device. Hence, they are not available in consumer sizes.


  • They have superior energy density.
  • Also, they are small and thin.
  • Even so, they have quick recharge and low self-discharge.
  • When new, they do not require a prolonged charge.
  • It is not harmful to the environment.
  • Lastly, it offers maximum performance.


  • It is not available in household sizes.
  • Also, they require a protection circuit for protection.
  • Only a specific type of charger can be used.
  • Lastly, its overall capacity reduces with time.

Nickel Cadmium (NiCd) Batteries

These cells are popularly used in toys, digital cameras, etc. You can see them in standard sizes of AA, AAA, C, and 9V.

Also, they maintain steady voltage until its total depletion. It has about 1.2V per cell. Thus, its voltage is not high. However, its powerful delivery makes up for the low voltage.


  • They are readily available and cheap.
  • Also, it charges and discharges quickly.
  • Lastly, it delivers power at full capacity.


  • They do not store energy for a long time.
  • Also, they contain toxic materials. Hence, they are not environmentally friendly.
  • Even so, they use a specific type of charger.
  • Its capacity can decline due to over-charging.
  • Lastly, it must completely discharge before you can recharge.

Nickel-Metal Hydride Batteries

The nickel-metal hydride (NiMH) batteries have a reduced cycle life. Though, it offers a high density. However, you can only recharge it about 500 times.

Also, they deliver full capacity until they are completely discharged. They are useful for 30 days. After which they are no more useful.


  • Its energy-to-volume ratio is high.
  • Also, they are friendly to the environment.
  • Lastly, they deliver at full capacity.


  • It requires a full charge before use.
  • Also, its battery capacity might decline due to overcharging.
  • Even so, it discharges at a high rate.

Nickel-Iron (NiFe) Batteries

The nickel-iron batteries can withstand overcharging and discharging. They also function well with high temperatures and vibrations resistance.

The NiFe batteries use potassium hydroxide (KOH) as their electrolyte. Its anode and cathode are made of iron and oxide-hydroxide respectively.

They are used in railroad signaling, mines, and trucks/forklifts. However, they perform very low at lower temperatures.

More so, it is expensive. It discharges at the rate of about 40% per month.


  • They can withstand overcharging and discharging.
  • Also, they are resilient to high temperatures and vibrations.


  • They are expensive.
  • Also, their discharge rate is high.
  • More so, they have low energy density.
  • It has low performance with low temperature.

Lead Acid Batteries

Lead-acid batteries are one of the most popular batteries used in photovoltaic systems. Despite its low energy, it has a well-established and mature technology base.

It consists of a negative electrode made of porous lead. Also, its positive electrode is lead oxide. Even so, its electrolyte is sulphuric acid (tetraoxosulphate (vi) acid) and water.

However, these two electrodes are separated by an electrically insulating and chemically permeable membrane. Thus, they store energy through a reversible chemical reaction.


  • They have a well-established technology base.
  • Also, they are inexpensive compared to other cells.
  • Even so, they are durable.


  • They have low energy density.
  • More so, their efficiency is moderate.
  • Even so, they require high maintenance.

Absorbent Glass Mat (AGM) Technology

The AGM or Absorbent Glass Mat is a technology used in the lead-acid battery to provide superior power. It is an advanced lead-acid cell that supports higher electrical demands.

The AGM batteries are totally sealed and are resistant to vibration. They are used in start-stop vehicles, photovoltaic systems, large audio systems, etc.

What Is A Battery: Capacity And Size

The battery capacity is the amount of charge the battery can hold. With the battery capacity rating, you can figure out the duration the battery can last.

It is measured in milliampere-hours (mAh) or ampere-hours (Ah).

Thus, battery capacity = Current rating * time.

Generally, the higher the battery capacity, the longer its lifespan. However, this depends on what you use the battery for.

In practice, they have different sizes and their voltage rating differs. The table below shows the standard battery sizes and their rated voltages.

Battery SizeRated Voltage
Double-A (AA) Batteries1.5 volts
Triple-A (AAA) Batteries1.5 volts
Quadruple A (AAAA) Batteries1.5 volts
C Batteries1.5 volts
D Batteries1.5 volts
9V Batteries9 volts
CR123A Batteries3 volts
23A Batteries12 volts
CR2032 Batteries3 volts
12V Batteries12 volts
22V Batteries22 volts
44V Batteries44 volts

What Is A Battery: Connection

What Is A Battery_ Connection

The cell is the source of DC in a circuit. However, every circuit has a rated voltage and current at which it operates. More so, this voltage brings about current flow.

Nevertheless, the combination of two or more cells can either increase the current, voltage or both, depending on the connection. This connection could be series, parallel, or series-parallel.

Let’s assume the voltage of a battery to be “E”, its current to be “I”, and its internal resistance to be “r”.

Cells In Series

Assuming we have two identical cells B1 and B2 connected in series, – then the positive terminal of B1 will be connected to the negative terminal of B2. Thus, the negative terminal of B1 and the positive terminal of B2 becomes the terminals of the two cells.

If the voltage of B1 is E1 with internal resistance r1 and current I1, – and the voltage of B2 is E2 with an internal resistance of r2 and current I2, – then, the total voltage will be Et, total current It, and total internal resistance rt.


Et = E1 + E2.

rt = r1 + r2.

It = I1 =I2.

Cells In Parallel

If the same identical cells above are connected in parallel, – then the positive terminals will be connected together and the negative terminals connected together as well.


Et = E1 = E2.

rt = (r1 * r2)/(r1 + r2).

It = I1 + I2.

Cells In Series-Parallel

The series-parallel is a combination of both series and parallel connections. This might be a little complex but it is easy to connect. However, the series-parallel connection depends on the amount of current and voltage the circuit needs.

Also, the voltage and current ratings of the cells contribute to this connection. Thus, identical cells should be used for these connections.

What Is A Battery: Solar Batteries

A solar battery is a secondary (rechargeable) cell that you can use to store electrical energy generated from your solar panels. It’s a fast-growing technology that provides an alternative power supply when there is a power failure in the public supply system.

The battery charges via the direct current which the solar panel generates. More so, the solar panel directly converts the light energy from the sun into a direct current. Thus, the DC charges the battery.

Furthermore, there are two common options of battery types used in producing solar batteries. These are the Lithium-ion batteries and the lead-acid batteries.

Manufacturers prefer using lithium-ion battery technology because of its higher efficiency compared to lead-acid batteries. They store more energy and hold the energy for a longer time.

Even so, they have a higher depth of discharge (DoD). The depth of discharge is the percentage at which you can safely use a battery, with respect to its total capacity.

If the DoD of a battery is 92%, then you can use 92% of the battery capacity safely before recharging.

What Is A Battery: My Recommendations

What Is A Battery_ My Recommendations

The recommendations below are batteries suitable for your solar energy system. They are the 5 best available solar batteries that are perfect for your photovoltaic system.

However, I will be listing these top picks from the best to the 5th in ascending order.

ProductDimensionWeightSizeCell CompositionBrand
ML35-12 – 12V 35AH U1 Deep Cycle AGM Solar Battery‎9 x 9 x 6.2 inches‎23.2 pounds12V 35AhLead-Acid, AGMMighty Max Battery
PS-1270 – POWER-SONIC 12V 7AH SLA BATTERY5.95 x 2.56 x 3.86 inches‎5 pounds12V 7AhSealed Lead AcidPower-Sonic
Weize 12V 75AH Deep Cycle Battery10.2 in x 6.61 in x 8.31 inches49.6 pounds12V 75AhSealed Lead AcidWEIZE
Renogy 12V 100AH Deep Cycle Hybrid Gel Battery12.9 x 6.8 x 8.7 inches63.9 pounds12V 100AhHybrid gelRenogy
12V 10Ah Lithium LiFePO4 Deep Cycle Battery5.94 x 2.56 x 3.7 inches2.64 pounds12V 10AhLithium-IonNERMAK

Frequently Asked Questions

Frequently Asked Questions
1. What is a battery’s simple definition?

It is a device that converts its stored chemical energy to electrical energy.

2. What is in a battery?

The constituents of e battery are container, anode, cathode, electrolyte, collector, and separator.

3. What is a battery used for?

They are used to accept, store, and release electrical energy on demand.

4. What are batteries and cells?

A cell is a device that converts chemical energy to electrical energy. While the battery is a collection of cells.

5. How does a battery charge?

This has to do with converting electrical energy to chemical energy. During this process, the battery reacts in the opposite of while it was discharging.

6. What type of cell is a battery?

Batteries are galvanic cells

7. Is the battery AC or DC?

Direct Current DC

8. What are the 4 types of batteries?

The 4 most popular batteries are:
(a). Alkaline batteries
(b). Nickel Metal Hydride batteries
(c). Lithium-Ion Batteries
(d). Lead-acid Batteries

9. Why battery is used in the circuit?

The battery supplies energy to the circuit.

10. Do batteries make electricity?

Batteries produce direct current. Hence, they produce electricity.

What Is A Battery: My Final Thought

What Is A Battery_ My Final Thought

The battery is of great benefit in modern days. Thanks to Alessandro Volta for his work as well as other scientists that also experimented on it.

It has helped in providing alternative energy sources in this modern times. Also, it is been used to power most electronic devices.

However, this article has all the information you require on Batteries. It gives a detailed explanation of its existence, uses, types, etc.

Even so, it gives a mathematical tip on how to double voltage and current through the connection of two or more cells. Even so, it recommends the 5 best solar batteries for you if you need them.

I hope you found this article useful to you.

Then, fill out the”Leave A Reply” form to share your thoughts.

To read more of the articles on this site, please visit;

What Is An AGM Battery?

5 Best Deep Cycle Battery Chargers

What Is The Best Battery For Solar?

Christian Jerome
Akan Christian writes for PowerVersity.com. He holds an HND in Electrical/Electronic Engineering. Christian enjoys reading, listening to solemn music, singing, and playing sports. For PowerVersity.com, Christian writes reviews, buying guides, and best pick articles.


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