Car Batteries: How Do They Work?

Have you ever wondered how a small, seemingly ordinary box tucked away in the engine bay of your car has the power to bring it to life? We're talking about car batteries, those unsung heroes of automotive technology that silently work their magic to keep our vehicles running smoothly.


  1. Basic Anatomy of a Car Battery
  2. Chemical Reaction
  3. What Does The Car Battery Do Exactly

Basic Anatomy of a Car Battery

If you want to know how something works, you first have to get to know its components. Here are the basics of a batteries parts:

  • Case: The outer housing of the battery is usually made of durable plastic.
  • Electrolyte: A mixture of sulfuric acid and distilled water, responsible for creating a chemical reaction.
  • Plates: Lead plates immersed in the electrolyte, where the energy exchange occurs.
  • Separators: Insulating material placed between the plates to prevent short circuits.
  • Terminals: The positive (+) and negative (-) terminals used for electrical connections.

Chemical Reaction

The short answer to how a car battery works is: Chemical reactions that transfer electricity into chemical energy. Looking for a more in-depth explanation? Here it is:

  • Lead-Acid Chemistry: Most car batteries use lead-acid chemistry, where the lead plates undergo a series of reactions with the sulfuric acid in the electrolyte. This creates a flow of electrons, generating electrical energy.
  • Electrolysis: When the battery is charged, an electrical current passes through the electrolyte, causing water molecules to split into hydrogen and oxygen gasses.
  • Recharging: When the engine is running, the alternator replenishes the charge in the battery by converting mechanical energy into electrical energy. This reverses the chemical reactions, allowing the battery to be used again.

What Does The Car Battery Do Exactly

The primary function of a car battery is to provide a burst of energy to start the engine. After it starts the engine, the alternator takes over the supply of electricity to all parts.

  • Cranking Amps (CA): Car batteries are rated in terms of cranking amps, which indicates their ability to deliver a high current for a short period. When you turn the ignition key, the battery releases a surge of electrical energy to the starter motor, initiating the combustion process.
  • Recharging During Driving: Once the engine is running, the alternator takes over the electrical load, supplying power to the vehicle's systems and recharging the battery simultaneously.

If your car battery starts malfunctioning or you experience any other problems, Autoworks of Issaquah is here to help! Simply book an appointment or visit us straight away.

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