Powering future

Everything you need to know about lead-acid automotive batteries

Everything you need to know about lead-acid automotive batteries

Batteries are an essential part of a vehicle and should not be overlooked. Without a good battery, the car stalls. We are responsible for how long our vehicle can withstand. To extend their useful life, we must maintain them properly. Maintenance-free batteries are slowly taking over from lead-acid batteries, but it is important to understand that the basic principle remains the same. We will discuss all the important aspects of a battery in this article.

How does a battery work?

Lead-acid automotive batteries are energy storage devices made up of lead plates and lead dioxide. These plates are immersed in an electrolyte solution. The percentage of water is 65% and sulfuric acid contributes 35% to this solution. When the battery is used to start the car, it discharges. The sulfuric acid in the electrolyte solution is depleted leaving a larger proportion of water. The sulfate is returned to the acid during the charging process. The battery provides high current required by the starter motor to start the car engine. Once the engine is started, the engine-driven charging system recharges the battery. In this process, the alternator takes the necessary energy from the rotation of the engine through a belt to charge the battery. When the engine is running, the alternator generates electricity for the car’s electrical equipment.

What weakens a battery?

When the car is exposed to direct sunlight in summers for longer periods of time, it accelerates the corrosion process and evaporates the electrolyte. This reduces the life of a battery by making it weaker. Therefore, prevent your car from being heated by sunlight by parking in adequate shade.

A battery must be correctly installed to avoid any type of vibration. These vibrations over time shake the plates around which in turn cause the internal connections to be lost. As a result, the battery would not charge properly.

Once you start the car, be sure to drive it long enough for the battery to recharge. The alternator takes time to recharge the battery after it has released its energy when starting the engine. Otherwise, the battery will remain low, which is not enough to provide high current to the starter motor.

Keeping the headlights or music system on while the engine is off drains the battery over time. Avoid plugging in a charger for a longer period of time to avoid discharging the battery.

Corrosion on battery terminals is just as damaging to the battery as anything else. Always clean the battery terminals carefully once or twice a month. Be sure to wear gloves and eye protection. The white powder on the terminals is toxic and should not be allowed to come into contact with the skin.

Signs that indicate battery replacement:

There are a couple of signs that may indicate that the battery is running low and needs a replacement.

  • The car’s bright headlights dim slightly when the engine is turned off.

  • The starter motor turns slowly when starting the car due to the low current provided by the battery.

There are some visual signs that the battery needs a replacement.

  • An internal short circuit or overload causes the battery to swell. If you see signs of bulging anywhere around the battery, replace it.

  • Examine the battery box carefully for any damage to the battery box.

How to start an engine with a weak battery?

Using a weak battery is not recommended. However, in an emergency, jumper cables can be used when you are stuck during your journey along the highway. Always keep a set of jumper cables in your car if you think the battery is not in optimal condition. Jumper cables allow you to start your vehicle with the help of another car. Although it is a very simple technique but safety measures must be taken to avoid any danger. The following steps will guide you to start the vehicle:

  • Make sure both batteries have the same rated voltage, i.e. 12V

  • Turn off the ignition switch after parking it close enough to the other car in the neutral position.

  • Never skip a frozen battery. It can easily explode.

  • Wear rubber gloves and safety glasses.

  • Carefully identify and connect the positive terminals of both batteries to each other.

  • Make sure the other end does not touch the car body to avoid dangerous sparks.

  • Attach the negative cable to the negative terminal of the good battery.

  • Connect the other end of the negative cable to a metal part of the car that has a low battery.

  • Finally start the car with the battery in good condition.

  • Wait 5 to 7 minutes to charge the weak battery.

  • Now start the car ignition with the discharged battery.

  • Carefully remove the cables in reverse order. First remove the negative cables and then remove the positive cable from the car with the good battery. In the end, remove the positive cable from the car with a weak battery.

How to check the battery status?

For proper battery maintenance, schedule once a month to check battery status. Today there are tools that can help measure the current state of the battery. Below 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 voltage readings up to 16V along with the battery status indicator. It has positive and negative probes. Inside, there is a high current capacity coil that provides the necessary load with a toggle switch. Battery voltage can be easily tested by following these steps:

  • Turn off the car’s engine.

  • Connect the positive probe of the load tester to the positive terminal of the battery.

  • Similarly, connect the negative probe with the negative terminal.

  • Make sure both probes are properly connected to the battery terminals.

  • The meter will display a voltage reading according to the condition of the battery.

  • Now turn on the charging toggle switch for 05-07 seconds to measure the battery charging voltage.

  • A healthy battery ideally shows 12.5 volts.

  • If the meter needle drifts anywhere near the “weak” indication, replace the battery immediately.

  • Safely remove the probes in reverse order.


The hydrometer is another tool for measuring the condition of the battery. It measures the specific gravity of the electrolyte, but can only be used with batteries with removable caps. Hydrometers usually have a built-in thermometer. Follow these simple steps to measure the remaining battery life:

  • Start by removing the covers from the top of the battery.

  • Dip the tip of the hydrometer into the first battery cell.

  • Squeeze and release from behind to allow electrolyte to enter hydrometer cylinder.

  • Read the specific gravity of the electrolyte as indicated.

  • Write down the reading of all cells one by one.

  • Compare the readings with those on the hydrometer.

  • Generally, readings between 1,265 and 1,299 indicate that the battery is charged. Any reading below this bracket shows signs of a weak battery.

  • Another method of examining the condition of the battery is to use a multimeter. This process is similar to the one we use for the battery charge tester.

How to replace a battery?

A car battery can be easily replaced at home without any complications by following these simple steps:

Removing the old battery:

  • Start by removing the negative battery terminal, usually marked black or with the (-) symbol to avoid any arcing with the wrench.

  • Disconnect the positive terminal usually marked red or with the (+) symbol.

  • Remove the “holding clamp” from the battery

  • Batteries are heavy, so lift them carefully.

  • Clean the battery tray if it is corroded.

New battery connection:

  • Carefully lift the new battery into position.

  • First connect the “holding clamp” correctly.

  • Connect the battery terminals in reverse order by connecting the positive terminal first.

  • Connect the negative battery terminal.

  • Make sure the connections are not loose.

  • The battery must be fixed correctly to avoid vibrations.

  • Terminals must be clean.

  • Add a little petroleum jelly on both terminals as it reduces the corrosion process.

The old battery can be sold to a battery store where you bought the new one. These car batteries are also recycled to prevent hazardous chemicals from reaching the atmosphere. Old lead plates can also be recycled into other products.

How to maintain your battery?

To prolong battery life, it must be kept in good condition. Schedule battery maintenance every month. It includes the following things:

Cleaning the battery and its terminals:

Cleaning a battery involves removing corrosion or any white dust from the battery terminals and surface. For this purpose, use warm water and add a tablespoon of baking soda. Carefully remove the battery (as mentioned in the replacement section) Make sure the removable caps are tight. Always wear rubber gloves because the white powder is toxic and should not be allowed to come into contact with the skin. Completely apply the solution to the battery box. Clean the terminals properly. Use a brush to get into tight spaces. Let the solution sit for a couple of minutes and then wash it off with cold water. The terminals will be free of corrosion after this practice. Reinstall the battery into position carefully.

Electrolyte level inspection:

The electrolyte level within a battery can be visually examined by removing the caps on the top of the battery. Lead plates must be properly immersed in the electrolyte solution. If you see a decrease in the electrolyte level in any of the cells, add a little water. Let the solution mix properly.

Using a battery charger / maintainer:

If your car is idle for an extended period, use a battery charger to keep the battery properly charged. Batteries will soon run out if you don’t charge them. A battery charger can go a long way in maintaining the desired voltage output from the battery. It usually comes in different modes depending on the requirements i.e Charge, Boost Charge, and Maintainer. It can also be used to maintain battery voltage. Gently plug the charger into an outlet. Connect the positive cable to the positive battery terminal and the negative cable to the negative terminal. Turn on the switch and allow the battery to charge properly.

Always inspect the battery before going on a trip. Overlooking the battery status can get you into trouble in the middle of nowhere. A 10-15 minute inspection can help you save a lot of time during your trip. If you know of any other important things related to batteries, please mention them in the comments section below.

Leave a Reply

Your email address will not be published. Required fields are marked *