All You Need To Know About Lead-Acid Car Batteries

The battery is an important part of the vehicle and should not be ignored. Without a healthy battery, the car will start standstill. We are responsible for how long they can support our vehicles. To extend their life, we need to maintain them properly. Maintenance-free batteries are gradually replacing lead-acid batteries, but it is important to understand that the basics remain the same. In this article, we will discuss all the important aspects of batteries.

How does the battery work?

Lead-acid automotive batteries are energy storage devices composed of lead plates and lead dioxide plates. These plates are immersed in an electrolyte. The percentage of water is 65% and sulfuric acid accounts for 35% of the solution. When the battery is used to start the car, it drains. The sulfuric acid in the electrolyte is consumed, leaving more water. During the charging process, sulfate returns to the acid.

The battery can supply the high current that the starter motor needs to start the car engine. After the engine has started, the battery is charged via the engine powered charging system. In this process, the alternator draws the necessary energy from the rotation of the engine via a belt to charge the battery. When the engine is running, the alternator generates electricity for the car’s electrical equipment.

What causes low battery voltage?

In summer, when a car is exposed to direct sunlight for a long time, it speeds up the corrosion process and evaporates the electrolyte. This shortens battery life and makes it weaker. Therefore, do not park in the correct shade to prevent the car from being heated by sunlight.

The battery must be placed correctly to avoid any vibration. Over time, these vibrations will shake the record, causing internal connections to be lost. This prevents the battery from charging properly.

After starting the car, make sure that you drive enough time to recharge the battery fully. After the alternator has delivered energy when starting the engine, it takes a while for the battery to charge. Otherwise, the battery will remain underloaded and not sufficient to provide a large current for the starter motor.

With the engine off and the headlights or music system left on, the battery will drain over time. Avoid connecting the charger for a long time to avoid draining the battery.

Corrosion on the battery terminals is just as harmful to the battery. Carefully clean the battery terminals once or twice a month. Wear gloves and eye protection. The white powder on the terminal is poisonous and should not come into contact with the skin.

A sign indicating to change the battery:

  • There are several signs that your battery is low and needs to be replaced.
  • When the engine is off, the car’s headlights dim slightly.
  • When starting the car, the starter motor will turn slowly due to low battery current.

There are visual signs that the battery needs to be replaced.

  • An internal short circuit or overcharging can cause the battery to swell. If you find any signs of
  • bulging anywhere around the battery, replace the battery.
  • Carefully check for damage to the battery box.

How do I start the engine with a weak battery?

It is not recommended to use low power. However, in emergencies, you can use jumper cables if you get stuck while driving along the road. If you think the battery is not in top condition, keep a set of jumper cables in the car. The jumper cable allows you to start the vehicle using another vehicle quickly. While this is a straightforward technique, safety precautions must be taken to avoid any danger.

The following steps will help you start the vehicle quickly:

  • Make sure that both batteries have the same nominal voltage, namely 12 V.
  • Please turn off the ignition switch after stopping it close enough to the centre position of other vehicles.
  • Do not jump over the frozen battery. It explodes easily.
  • Wear rubber gloves and safety glasses.
  • Carefully identify and connect the positive terminals of the two batteries.
  • Make sure the other end does not touch the body to avoid dangerous sparks.
  • Clip the negative cable to the negative terminal of a normal battery.
  • Connect the other end of the negative cable to the metal part of the car with a weak current.
  • Finally, start the car with a good battery.
  • Give it 5 to 7 minutes to charge the weak current.
  • Now start the contact with a weak battery.
  • Carefully remove the cables in reverse order. Remove the negative lead first and then the positive lead from the car with a good battery. Finally, use a weak battery to remove the positive lead from the car.

How to check the battery condition?

Schedule a monthly check to check the battery status to maintain the battery properly. Today some tools can help measure the current state of the battery. The following are the most commonly used tools for this purpose:

Battery charge tester:

The battery charge tester is used to check the nominal voltage of the battery in operation. It has a display meter with a voltage reading up to 16V and a battery status indicator. It has positive and negative probes. Inside is a coil with a high current capacity, which can provide the necessary load via a toggle switch.

The following steps can easily test the battery voltage:

  • Turn off the car engine.
  • Connect the positive probe of the load tester to the positive electrode of the battery.
  • Connect the negative probe to the negative terminal in the same way.
  • Make sure that both probes are properly connected to the battery terminals.
  • The meter displays the voltage value based on the condition of the battery.
  • Now turn on the load switch for 05-07 seconds to measure the battery voltage on the load.
  • A healthy battery should ideally display 12.5 volts.
  • If the gauge needle deviates near the “weak” indicator, replace the battery immediately.
  • Safely remove the probe in reverse order.


A hydrometer is another tool to measure battery health. It can measure the specific gravity of the electrolyte, but it can only be used on batteries with removable covers. The hydrometer usually has a built-in thermometer. Follow these simple steps to measure remaining battery life:

  • First, remove the cover from the top of the battery.
  • Immerse the tip of the hydrometer in the first cell of the battery.
  • Squeeze and release it from the back to get the electrolyte into the cylinder of the hydrometer.
  • Follow the instructions to read the specific gravity of the electrolyte.
  • Note the readings of all cells.
  • Compare the reading with the reading on the hydrometer.
  • Typically, a reading between 1,265 and 1,299 indicates the battery is fully charged. Any reading under this standard indicates that the battery is low.
  • Another way to check battery health is to use a multimeter. This process is similar to the one we use for battery charge testers.

How do I replace the battery?

Follow these simple steps to replace the car battery at home easily:

Remove the old battery:

  • First, remove the negative battery, which is usually marked black or with a (-) symbol, to avoid sparking the key.
  • Disconnect the positive terminal, which is normally marked in red or with a (+) symbol.
  • “Clamping pliers” to remove the battery.
  • The battery is heavy, so lift it carefully.
  • If the battery box is corroded, clean it.

Connecting a new battery:

  • Carefully insert the new battery.
  • First, connect the “compression pliers” correctly.
  • First, connect the positive pole and connect the battery poles in reverse order.
  • Connect the negative terminal of the battery.
  • Make sure the connection is not loose.
  • The battery must be securely fastened to avoid vibrations.
  • The terminals must be clean.
  • Add some petroleum jelly to the two connections as it can reduce the corrosion process.

You can sell old batteries to battery stores that buy new ones. These car batteries are also recycled to prevent dangerous chemicals from entering the atmosphere. Old lead sheets can also be recycled into various other products.

How to maintain the battery?

To extend the life of the battery, it must be properly maintained. Schedule monthly battery maintenance. It includes the following:

Clean the battery and terminals:

Before cleaning the battery, remove any corrosion or white powder on the battery terminals and surface. To do this, use warm water and add a tablespoon of baking soda to it. Carefully remove the battery (as described in the chapter on replacement) and make sure the removable cover is secure. Always use rubber gloves as the white powder is poisonous and should not come into contact with the skin. Divide the solution thoroughly over the battery box. Clean the clamps well. Use a brush to reach a narrow space. Leave the solution on for a few minutes and then wash with cold water. After this, the terminals are free from corrosion. Carefully replace the battery.

Electrolyte level check:

The electrolyte level in the battery can be visually checked by removing the cover on the top of the battery. The lead plate must be properly immersed in the electrolyte. If you notice that the electrolyte level in one of the batteries has dropped, add some water. Let the solution mix well.

Use battery charger/maintainer:

If you are not going to use your car for a long time, use a battery charger to keep the battery properly charged. If you don’t charge the battery, the battery will run out quickly. The battery charger is handy to maintain the output voltage of the battery. Usually, it appears in different modes according to the requirements, namely charging, fast charging and maintenance personnel. It can also be used to maintain battery power. Carefully plug the charger into the wall socket. Connect the positive cable to the positive terminal of the battery and the negative cable to the negative terminal. Turn on the switch and let the battery charge normally.

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