How is a battery made?

Transport, lawn equipment, heavy machinery – they’re all reliant on good batteries. But what makes a battery good?

The trick is in knowing how a good battery is made.

Here, you can broaden your battery knowledge and find out what materials make a battery, how a battery works, and what is battery capacity – ultimately helping you to better understand your batteries for more informed decision-making.

How is a battery made (simple explanation)?

Regulations and consumer demands (comfort, safety, sustainability) have changed vehicle technology and the way that batteries need to be made. Automobile batteries are now needed to provide energy to many other accessories, including sensors, displays, safety features and infotainment systems.

There are also many different types of batteries available. However, put simply, a battery is made of eight components.

Considered the most important parts are the anode and cathode, which help to conduct the electricity. The anode draws oxygen atoms toward it, creating that electric flow.

Then there are the lead plates that, together, form battery cells. A cell produces electricity when one end of a cathode and one end of an anode are placed into a third substance that can conduct electricity, while their other ends are connected. In the case of how a battery is made, the anode and cathode are placed into an electrolyte –  a chemical combination that help makes a battery work. The electrolyte has a container, that can act as both that, and either the cathode or the anode.

In addition, a battery features plate separators, lead terminals, inter cell connectors, and vent and vent caps, which assist with the functionality and safety of that battery.

If you’re interested to learn more on battery operation, an informative video by The Engineering Mindset helps to further explain, in basic terms, how a battery works.

What materials are used to make a battery?

Range of car batteries onboard taken fro ma higher angle by Empower Battery Co

Traditional batteries are made from:

  • Lead – for positive and negative internal plates, plate blocks (battery cells), and the battery’s external connection points.
  • Porous synthetic material – to separate the plates.
  • Copper – for cell connectors.
  • Sulfuric acid and water – the electrolyte used in many batteries, also known as battery acid, which causes the chemical reactions that make a battery work.
  • Polypropylene – for the acid-resistant plastic container and cover.
  • Plastic – for the all-important vent caps, which allow the escape of gases formed inside the battery when it is being charged.

How does a battery work?

A battery works by storing chemical energy and converting it to electrical energy.

When current flows from a lead-acid battery, that battery will start to be discharged.

A chemical reaction takes place during discharge. The active materials in the electrodes react with the sulfuric acid in the electrolyte to form lead sulfate and water. When the battery is recharged – in a car this would be via the alternator as the car is driven around – the lead sulfate converts back to the lead dioxide and metallic lead, restoring the chemical difference between the plates. Batteries will go flat when the electrolyte’s chemicals dry up within the battery. 

The anatomy of that battery also has an impact on how it works – there are various chemical reactions that determine how much energy it can store, and its voltage.

What is battery capacity?

Battery capacity is a measure of the charge stored by a battery. It is determined by the mass of active material contained in the battery – the maximum amount of energy that can be extracted from the battery.

Battery capacity is measured in watt-hours (Wh), kilowatt-hours (kWh), or ampere-hours (Ahr), the latter being the most common – the number of amps the battery can provide over a certain number of hours.

The capacity of a battery varies depending on its age and history, its charging/ discharging regimes, and the temperature.

For any budding scientists out there, you can read more on the scientific explanation behind battery capacity in ScienceDirect:

Testing a car battery with a multimeter by Empower Battery Co

How is battery capacity related to voltage?

Capacity is the measure of the battery’s endurance. Voltage is a measure of a battery’s power. In general, the higher a battery’s voltage, the higher its capacity as well.

In a typical lead-acid battery, the voltage is approximately 2.11 volts per cell, for a total of 12 volts, and the average capacity is about 70 ampere-hours, specified at a current of 3.5 amps.

You may have heard people using different terminology when it comes to capacity and power. Here is some of that further explained.

Starting Power – also known as Cold Cranking Amps, CCA is a rating that defines a battery’s ability to start an engine in cold temperatures, i.e., the number of amps a 12-volt battery can deliver at -18°C for 30 seconds while maintaining a voltage of at least 7.2 volts per cell. Your vehicle’s electrical system is designed to pull a fixed amount of current for each specific task, so batteries with a higher CCA will not start your vehicle faster or make it perform better. However, batteries with a higher CCA rating do have the potential of lasting longer.

Reserve Capacity – also known as accessories power, this is a new, fully charged battery’s capacity to provide power to accessories if the vehicle’s alternator fails. To equally measure reserve capacity across batteries, it is presumed that the new battery is at 25C in temperature.

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