Car Battery: A Comprehensive Guide on Car Batteries

Serving as the heart of vehicles, a car battery has a crucial role in the working of cars. Then, how should we use it properly? Let us dig into the details related to car batteries.

Role of Car Battery in Starting the Car Engine

The main role of a car battery is to ignite the car engine. However, it also serves as a surge protector. Moreover, it also gives power to short-term use, such as lights, GPS, radio, or wipers, when the engine is not in use.

There is a whole starting system in a car of which the battery is a part. It mainly comprises the following components:

Ignition switch: it’s the “on button” of the car or where you insert the car key.

Starter Relay: the switch is connected to a starter relay. Upon ignition, a small electrical current passes, which closes the contacts.
Starter Motor: after the contacts close, the voltage is transferred to the starter motor, turning gears and the car starts.

Mechanic performing Car battery recharging.

Mechanic performing Car battery recharging.

The Working of a Car Battery

Usually, there are two types of Auto car batteries – AGM (Absorbent Glass Mat) and Flooded batteries. Both of these batteries utilize lead-acid technology to ignite the car engines.

A typical lead-acid battery has alternate lead plates with plates of some other material. All these plates are submerged in an electrolytic solution which contains 2/3rd water and 1/3rd sulphuric acid. 

When you turn on the ignition, it urges the acid in the electrolytic solution to react. The reaction of the acid takes place with the active material present in the plates. (Active material applies to any battery material that discharges or recharges the battery by reacting with the solution).

 Hence, an electrical current is generated, running to the overall starting system via a chain of reactions that signals the engine to start.

Why the Car Battery Recharges

The amount of electrical potential of a battery is called voltage. In simpler terms, the pressure from the power supply drives charged electrons via a conducting loop, allowing them to perform their function.

A car needs more power to ignite, which cannot be provided by small AAA batteries but a bulky battery with a certain amount of voltage.

Getting to know your power cell voltage 

A standard battery of the car has a voltage of 12 volts. However, there is a term used for car batteries – resting voltage, which is the amount of voltage that a car’s battery possesses when the car is turned off. 

Usually, the resting voltage for car batteries is 12.6 volts which gradually increases upon car running. As soon as your vehicle reaches full running, the alternator takes the role of powering.

It powers the electrical parts like lights, stereo, wipers, and power windows. 

Moreover, the alternator is in charge of recharging the battery to make it available the next time to start the car. 

Alongside the extra electrical power from the alternator, a car battery generally has a 13.5 to 14.5 voltage when the car is running.

Eventually, a voltage regulator is present to control the current flow. It controls the power and supplies the exact charge required to run the AC or heater. Also, avoid the overcharging of the battery which can lead to damage.

Voltage for your Car 

To perform its function properly, a battery needs a good amount of voltage. While there is a misconception that a battery must be zero before it stops working, this is not true.

The battery of a car cannot get down far below 12 volts before being incapable of performing its role. 

Here is a glimpse of a car battery charge concerning voltage to help you understand the working function of your car’s battery. 

Battery chargeVoltage
100 percent12.6 or greater
90 percent12.5
80 percent12.4
70 percent12.3
60 percent12.2
50 percent12.06
40 percent11.9
30 percent11.7
20 percent11.5
10 percent11.3
dead10.5 or lower

Reasons Why a Battery Dies

  • Happening of discharge-recharge reactions occur multiple times during the life of a battery. With every recharge cycle, a bit of plates wear out, and over time, the lead degenerates. Hence, the car battery’s capacity is lost, and ultimately CCA (cold cranking amps) also declines.
  • One more reason that leads car batteries to die is deep discharging, which usually occurs when battery usage implies running the stereo, lights, AC, or other electrical elements when the engine is off. This contributes to a major percentage of battery failures. 

Signs of a Drained Battery

Although several measuring instruments like multimeters or voltmeters easily determine the voltage of your vehicle battery. But, there are several signs that your car may show that correspond to the downhill of your battery. 

  • Electrical problems with the car, such as low or flickering headlights, slow stereo, or problems with the power windows, etc. 
  • Sometimes, complete loss of power to electrical elements.
  • Trouble in starting your car.

All these signs contribute to fading batteries, but the most affirmative sign for a drawing battery is trouble while starting the car. If the car doesn’t start, that’s a sign of a dead battery.

But, if the car starts after a few tries or delays, it is a major sign of a weak or drained battery.

Car battery with cables

Car batteries with cables

How to Charge Your Drained Car Battery?

It is not rocket science to charge a draining automotive battery. Still, it is a bit technical & proper guidance is always essential.

  1. The foremost step is to remove the power cell if necessary. However, it depends on your vehicle. Some cars have batteries placed under the seat, in the trunk, or under the fender. For this, you may need professional help to access the battery.
  2. The next thing to choose is the best car battery charger per your needs and circumstances.
  3. Link the positive cable of the charger to the positive terminal of the battery.
  4. Similarly, the negative terminal to the negative cable of the charger.
  5. Power on the charger.
  6. Adjust the timer.
  7. After reaching the set timer, power off the charger first and detach the cables.
The mechanic is pulling out a car battery

The mechanic is pulling out a car batteries

How to Jump Start Your Dead Car Battery?

With modern advancement, a jump starter portable battery pack is available, which helps kick-start a car without using an external power source or another car. 

It provides a quick burst of energy, which helps to ignite the car, and once the car engine is on, the alternator takes the role and starts recharging the car batteries.

Moreover, if you own an electric vehicle,  here is a detailed guide on charging it easily.

Replacement Needs for an automotive battery.

Every car battery has a certain life span! After which it needs a replacement. According to car battery experts, a car battery should be replaced every three years. Nevertheless, a replacement can be needed sooner, depending on usage. 

  • The climate of your area.
  • Driving habits and frequency

Jump-starting may work in an emergency, but it is better to check your car batteries before any major problem arises.

Car battery replacement

Car batteries replacement


We have shared the most important details & information related to car batteries within this article – by which you will have an ample amount of knowledge about them.

To get an expert opinion or further information, you can always visit our website.